Melamine formaldehyde foam(MFF)generates many poisonous chemicals through the traditional recycling methods for organic resin wastes.Herein,a high MFF degradation ratio of ca.97 wt.%was achieved under the mild conditi...Melamine formaldehyde foam(MFF)generates many poisonous chemicals through the traditional recycling methods for organic resin wastes.Herein,a high MFF degradation ratio of ca.97 wt.%was achieved under the mild conditions(160℃)in a NaOH–H2O system with ammelide and ammeline as the main degradation products.The alkaline solvent had an obvious corrosion effect for MFF,as indicated by scanning electron microscopy(SEM).The reaction process and products distribution were studied by Fourier-transform infrared spectroscopy(FTIR),X-ray photoelectron spectroscopy(XPS),and ^(13)C nuclear magnetic resonance(NMR).Besides,the MFF degradation products that have the similar chemical structures and bonding performances to those of melamine can be directly used as the raw material for synthesis of melamine urea-formaldehyde resins(MUFs).Moreover,the degradation system demonstrated here showed the high degradation efficiency after reusing for 7 times.The degradation process generated few harmful pollutants and no pre-or post-treatments were required,which proves its feasibility in the safe removal or recovery of waste MFF.展开更多
Due to its ability to cause illnesses and discomfort even at low concentrations, formaldehyde pollution of indoor air poses a significant risk to human health. Sources of formaldehyde in indoor environments include te...Due to its ability to cause illnesses and discomfort even at low concentrations, formaldehyde pollution of indoor air poses a significant risk to human health. Sources of formaldehyde in indoor environments include textiles, paints, wallpapers, glues, adhesives, varnishes, and lacquers;furniture and wooden products like particleboard, plywood, and medium-density fiberboard that contain formaldehyde-based resins;shoe products;cosmetics;electronic devices;and other consumer goods like paper products and insecticides. According to the World Health Organisation, indoor formaldehyde concentrations shouldn’t exceed 0.1 mg/m<sup>3</sup>. The methods include membrane separation, plasma, photocatalytic decomposition, physisorption, chemisorption, biological and botanical filtration, and catalytic oxidation. Materials based on metal oxides and supported noble metals work as oxidation catalysts. Consequently, a paint that passively eliminates aldehydes from buildings can be developed by adding absorbents and formaldehyde scavengers to the latex composition. It will be crucial to develop techniques for the careful detection and removal of formaldehyde in the future. Additionally, microbial decomposition is less expensive and produces fewer pollutants. The main goal of future research will be to develop a biological air quality control system that will boost the effectiveness of formaldehyde elimination. The various methods of removing formaldehyde through paints have been reviewed here, including the use of mixed metal oxides, formaldehyde-absorbing emulsions, nano titanium dioxide, catalytic oxidation, and aromatic formaldehyde abating materials that can improve indoor air quality.展开更多
This research focuses on the evaluation of diverse approaches for removing formaldehyde from indoor environments,which is a significant concern for indoor air quality.The study systematically examines physical,chemica...This research focuses on the evaluation of diverse approaches for removing formaldehyde from indoor environments,which is a significant concern for indoor air quality.The study systematically examines physical,chemical,and biological methods to ascertain their effectiveness in formaldehyde mitigation.Physical methods,including air circulation and adsorption,particularly with activated carbon and molecular sieves,are assessed for their efficiency in various concentration scenarios.Chemical methods,such as photocatalytic oxidation using titanium dioxide and plasma technology,are analyzed for their ability to decompose formaldehyde into non-toxic substances.Additionally,biological methods involving plant purification and microbial transformation are explored for their eco-friendly and sustainable removal capabilities.The paper concludes that while each method has its merits,a combined approach may offer the most effective solution for reducing indoor formaldehyde levels.The study underscores the need for further research to integrate these methods in a practical,cost-effective,and environmentally sustainable manner,highlighting their potential to improve indoor air quality significantly.展开更多
Membrane contactor is regarded as a promising method for reaction and process intensification. The feasibility of formaldehyde carbonylation to synthesize glycolic acid using polytetrafluoroethylene(PTFE)membrane cont...Membrane contactor is regarded as a promising method for reaction and process intensification. The feasibility of formaldehyde carbonylation to synthesize glycolic acid using polytetrafluoroethylene(PTFE)membrane contactor has been proved in our previous study. In this paper, the effect of membrane microstructure on process performance was further investigated. Three porous PTFE hollow fibers with different pore sizes and one polydimethylsiloxane(PDMS)/PTFE composite membrane with dense layer were fabricated for comparison. The physical and chemical properties of four membranes, including chemical composition, morphology, contact angle, liquid entry pressure, thermodynamic analysis and gas permeability, were systemically characterized. Experiments of formaldehyde carbonylation under different reaction conditions were conducted. The results indicated that the yield of glycolic acid increased with decreasing pore size for porous membranes, which was due to the improvement of wetting behavior. The dense layer of PDMS in composite hollow fiber could effectively prevent the solvent from entering membrane pores, thus the membrane exhibited the best performance. At reaction temperature of 120℃ and operation pressure of 3.0 MPa, the yield of glycolic acid was always higher than 90% as the mass ratio of trioxane and phosphotungstic acid increased from 0.2:1 to 0.8:1. The highest turnover frequency was up to 26.37 mol·g^(-1)·h^(-1). This study provided a reference for the understanding and optimization of membrane contactors for the synthesis of glycolic acid using solvent with low surface tension.展开更多
Rod milling sand(RMS)—a coarse sand aggregate—was recycled for cemented paste backfill(CPB)for the underground mined area at the Jinchuan nickel deposit,named rod milling sand-based cemented paste backfill(RCPB).The...Rod milling sand(RMS)—a coarse sand aggregate—was recycled for cemented paste backfill(CPB)for the underground mined area at the Jinchuan nickel deposit,named rod milling sand-based cemented paste backfill(RCPB).The adverse effects of coarse particles on the transportation of CPB slurry through pipelines to underground stopes resulting in weakening of the stability of the backfill system are well known.Therefore,sulfonated naphthalene formaldehyde(SNF)condensate was used for the performance improvement of RCPB.The synergistic effect of solid content(SC),lime-to-sand ratio,and SNF dosage on the rheological and physicomechanical properties,including slump,yield stress,bleeding rate,uniaxial compressive strength(UCS),as well as mechanism analysis of RCPB,have been explored.The results indicate that the effect of SNF on RCPB performance is related to the SNF dosage,lime-to-sand ratio,and SC.The slump of fresh RCPB with 0.1wt%-0.5wt%SNF increased by 2.6%-26.2%,whereas the yield stress reduced by 4.1%-50.3%,indicating better workability and improved cohesiveness of the mix.The bleeding rate of fresh RCPB decreased first and then rose with the increase of SNF dosage,and the peak decrease was 67.67%.UCS of RCPB first increased and then decreased with the increase of SNF dosage.At the optimal SNF addition ratio of 0.3wt%,the UCS of RCPB curing for 7,14 and,28 d ages increased by 31.5%,28.4%,and 29.5%,respectively.The beneficial effects of SNF in enhancing the early UCS of RCPB have been corroborated.However,the later UCS increases at a slower rate.The research findings may guide the design and preparation of RCPB with adequate performance for practical applications.展开更多
Formaldehyde(HCHO)has been identified as one of the most common indoor pollutions nowadays.Manganese oxides(MnO_(x))are considered to be a promising catalytic material used in indoor HCHO oxidation removal due to thei...Formaldehyde(HCHO)has been identified as one of the most common indoor pollutions nowadays.Manganese oxides(MnO_(x))are considered to be a promising catalytic material used in indoor HCHO oxidation removal due to their high catalytic activity,low-cost,and environmentally friendly.In this paper,the progress in developing MnO_(x)-based catalysts for HCHO removal is comprehensively reviewed for exploring the mechanisms of catalytic oxidation and catalytic deactivation.The catalytic oxidation mechanisms based on three typical theory models(Mars-van-Krevelen,Eley-Rideal and Langmuir-Hinshelwood)are discussed and summarized.Furthermore,the research status of catalytic deactivation,catalysts’regeneration and integrated application of MnO_(x)-based catalysts for indoor HCHO removal are detailed in the review.Finally,the technical challenges in developing MnO_(x)-based catalysts for indoor HCHO removal are analyzed and the possible research direction is also proposed for overcoming the challenges toward practical application of such catalysts.展开更多
The study characterized the curing behaviors of phenol formaldehyde(PF)resin under different vacuum degrees and explored the properties of 9-ply plywood panels hot-pressed under both vacuum and atmospheric conditions....The study characterized the curing behaviors of phenol formaldehyde(PF)resin under different vacuum degrees and explored the properties of 9-ply plywood panels hot-pressed under both vacuum and atmospheric conditions.The changes in core temperature and moisture content of the plywood mats during hot pressing were investigated as well.It was found that the gel times and gel temperatures of PF resin decreased with the increase of vacuum degree using a self-made device.FTIR spectra indicated the degree of polycondensation of hydroxymethyl gradu-ally increased with the increase in temperature.It was also observed that a higher degree of vacuum led to a slower polycondensation reaction rate of PF resin.During different hot-pressing processes,the bonding strengths in the innermost and uppermost gluelines of the vacuum hot-pressed plywood panels were up to 30%–50%higher than their counterparts of conventional hot-pressed products.A less difference in the bonding strengths between these two gluelines was also observed for vacuum hot-pressed products.In addition,the core of vacuum hot-pressed plywood was found to have a greater heating rate and higher temperature at thefinal stage of hot pressing,which was beneficial to cure the PF resin.The results from this study indicate a promising potential of introducing a vacuum during hot pressing to improve the quality and productivity of plywood products and provide a basis for adopting vacuum to hot press wood composites.展开更多
Objective: The aim of this study was to compare the olfactory function between hairdressers exposed to formaldehyde and unexposed controls, as exposure to toxic agents is a potential cause of olfactory disorders in hu...Objective: The aim of this study was to compare the olfactory function between hairdressers exposed to formaldehyde and unexposed controls, as exposure to toxic agents is a potential cause of olfactory disorders in humans. Hairdressing professionals frequently encounter formaldehyde, a component found in hair products that are known to have various toxic effects on the human body, including alterations in the sense of smell. Methods: A total of 32 hairdressing volunteers exposed to formaldehyde and 32 non-exposed volunteers matched for age, sex, education and smoking status underwent the University of Pennsylvania Smell Identification Test (UPSIT<sup>®</sup>). Results: The findings demonstrated a decrease in UPSIT<sup>®</sup> olfactory test scores and a higher degree of olfactory loss among hairdressers exposed to formaldehyde (mean UPSIT<sup>®</sup> scores: 30.6 vs 35.1, p Conclusion: Occupational exposure of hairdressers to formaldehyde is associated with diminished olfactory function. Education approach and promotion of personal protective equipment usage should be encouraged.展开更多
Objective: The aim of this study was to compare the olfactory function between hairdressers exposed to formaldehyde and unexposed controls, as exposure to toxic agents is a potential cause of olfactory disorders in hu...Objective: The aim of this study was to compare the olfactory function between hairdressers exposed to formaldehyde and unexposed controls, as exposure to toxic agents is a potential cause of olfactory disorders in humans. Hairdressing professionals frequently encounter formaldehyde, a component found in hair products that are known to have various toxic effects on the human body, including alterations in the sense of smell. Methods: A total of 32 hairdressing volunteers exposed to formaldehyde and 32 non-exposed volunteers matched for age, sex, education and smoking status underwent the University of Pennsylvania Smell Identification Test (UPSIT<sup>®</sup>). Results: The findings demonstrated a decrease in UPSIT<sup>®</sup> olfactory test scores and a higher degree of olfactory loss among hairdressers exposed to formaldehyde (mean UPSIT<sup>®</sup> scores: 30.6 vs 35.1, p Conclusion: Occupational exposure of hairdressers to formaldehyde is associated with diminished olfactory function. Education approach and promotion of personal protective equipment usage should be encouraged.展开更多
For manufacturing low-formaldehyde emission particleboard from wheat straw and urea-formaldehyde (UF) resins using urea treatment for indoor environments, we investigated the influence of urea treatment on the forma...For manufacturing low-formaldehyde emission particleboard from wheat straw and urea-formaldehyde (UF) resins using urea treatment for indoor environments, we investigated the influence of urea treatment on the formaldehyde emission, physical and mechanical properties of the manufactured particleboard. Wheat straws were treated at three levels of urea concentration (5%, 10%, 15%) and 95℃ as holding temperature. Wheat straw particleboards were manufactured using hot press at 180℃ and 3 MPa with two types of UF adhesive (UF-45, UF-91). Then the formaldehyde emission values, physical properties and mechanical properties were considered. The results show that the for- maldehyde emission value was decreased by increasing urea concentration. Furthermore, the results indicate that the specimens under urea treatment have better mechanical and physical properties compared with control specimens. Also specimens under urea treatment at 10% concentration and UF-91 type adhesive have the most optimum physical and mechanical strength.展开更多
In this study Eucalyptus tannin (T) was isolated from outer bark of Eucalyptus trees;as sodium phenoxide salt and used as extender or copolymer into phenol formaldehyde (PF) resin at five percent (10, 20, 30, 40 and 5...In this study Eucalyptus tannin (T) was isolated from outer bark of Eucalyptus trees;as sodium phenoxide salt and used as extender or copolymer into phenol formaldehyde (PF) resin at five percent (10, 20, 30, 40 and 50)% W/W. Tan-nin-phenol formaldehyde (TPF) and tannin formaldehyde-phenol formaldehyde (TFPF) resins that synthesized in this study were evaluated as adhesive material for cellulosic fibers by study the mechanical properties of the composite sheets .The results show that the substituting of (PF) with tannin at (10 –50)% W/W give resins with mechanical properties comparable or near to those of pure (PF) , where the tensile strength at break (Tb) ranging from 15.15 Mpa to 22.27 Mpa as compared with 17.6 Mpa for pure (PF);while the impact strength properties (Im) of composites sheets increased with increased the (T) percents which were about 5.16 KJ/m2 for (TPF – 10%) and 7.21 KJ/m2 for (TPF - 50%) .On the other hand modification of (T) to tannin formaldehyde resin (TF) appear less performance at the results of this study , this effect probably to low penetration of (TFPF) resins between the small voids of cellulose fibers when soaked it in resin solutions. In general the results of this study indicate that the Eucalyptus tannin can be used for par-tial substitution of (PF) to produce resins with feasible mechanical properties and can be used in some applications of (PF) resins.展开更多
Aim: To investigate the effect of formaldehyde (FA) on testes and the protective effect of vitamin E (VE) against oxidative damage by FA in the testes of adult rats. Methods: Thirty rats were randomly divided in...Aim: To investigate the effect of formaldehyde (FA) on testes and the protective effect of vitamin E (VE) against oxidative damage by FA in the testes of adult rats. Methods: Thirty rats were randomly divided into three groups: (1) control; (2) FA treatment group (FAt); and (3) FAt + VE group. FAt and FAt + VE groups were exposed to FA by inhalation at a concentration of 10 mg/m^3 for 2 weeks. In addition, FAt + VE group were orally administered VE during the 2-week FA treatment. After the treatment, the histopathological and biochemical changes in testes, as well as the quantity and quality of sperm, were observed. Results: The testicular weight, the quantity and quality of sperm, the activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and glutathione (GSH) were significantly decreased whereas the level of malondialdehyde (MDA) was significantly increased in testes of rats in FAt group compared with those in the control group. VE treatment restored these parameters in FAt + VE group. In addition, microscopy with hematoxylin-eosin (HE) staining showed that seminiferous tubules atrophied, seminiferous epithelial cells disintegrated and shed in rats in FAt group and VE treatment significantly improved the testicular structure in FAt + VE group. Conclusion: FA destroys the testicular structure and function in adult rats by inducing oxidative stress, and this damage could be partially reversed by VE.展开更多
The amine-functionalized mesoporous silica materials were prepared via the co-condensation reaction of tetraethoxysilane and three types of organoalkoxysilanes: 3-aminopropyl-trimethoxysilane, n-(2-aminoethyl)-3-am...The amine-functionalized mesoporous silica materials were prepared via the co-condensation reaction of tetraethoxysilane and three types of organoalkoxysilanes: 3-aminopropyl-trimethoxysilane, n-(2-aminoethyl)-3-aminopropyltrimethoxysilane, and 3-(2-(2- aminoehtylamino)ethylamino) propyl-trimethoxysilane. Cetyltrimethylammonium bromide was used as a template for forming pores, Specific surface area and pore volume of the amine-functionalized mesoporous silica materials were determined using surface area and pore size analyzer. Fourier transform infrared (FTIR) spectroscope was employed for identifying the functional groups on pore surface. In addition, the amine-functionalized mesoporous silica materials were applied as adsorbents for adsorbing formaldehyde vapor. FTIR spectra showed the evidence of the reaction between formaldehyde molecules and amine groups on pore surface of adsorbents. The equilibrium data of formaldehyde adsorbed on the adsorbents were analyzed using the Langmuir, Freundlich and Temkin isotherm. The sample functionalized from n-(2-aminoethyl)-3-aminopropyltrimethoxysilane showed the highest adsorption capacity owing to its amine groups and the large pore diameter.展开更多
The present report evaluates the effects of formaldehyde (FA) exposure on peripheral lymphocytes by using heth genetic and immunological parameters. Twenty-three non-smoking students in the study had inhalation exposu...The present report evaluates the effects of formaldehyde (FA) exposure on peripheral lymphocytes by using heth genetic and immunological parameters. Twenty-three non-smoking students in the study had inhalation exposure to 0.508 ±0. 299 mg/m3 of FA for a Period of 8 weeks (3h × 3 times each week) during anatomy classes. As for composition of lymphocyte subsets after FA exposare,significant increase was found in the percentage of CD19(B cells), while sighficant decrease was observed in CD3(total T cells), CD4(T helper-inducer cells), and CD8(T cytotoxic-suppressior cells) with a P<0 .01. Increase in the ratio of T-helper-inducer cells to T-cytotoxic-suppressor cells (T4 / T8) was also observed with statistical sighcance after exposure (P < 0.001). In the meanwhile,no significant difference (P > 0 .05) was reported between lymphocyte prolifendion rate and sisterchromatid exchange (SCE) at the exposure level and duration. It is suggested that the lymphocyte subsets may be most susceptible to the effects of FA, though a single immunological endpoint is rarely related with pathophysiological interpretation.展开更多
Diatomite-based porous ceramics were adopted as carriers to immobilize nano-TiO2 via a hydrolysis-deposition technique. The thermal degradation of as-prepared composites was investigated using thermogravimetric-differ...Diatomite-based porous ceramics were adopted as carriers to immobilize nano-TiO2 via a hydrolysis-deposition technique. The thermal degradation of as-prepared composites was investigated using thermogravimetric-differential thermal analysis, and the phase and microstructure were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, and transmission electron microscopy. The results indicated that the carriers were encapsulated by nano-TiO2 with a thickness of 300-450 nm. The main crystalline phase of TiO2 calcined at 650~C was anatase, and the average grain size was 8.3 nm. The FT-IR absorption bands at 955.38 cm1 suggested that new chemical bonds among Ti, O, and Si had formed in the composites. The photocatalytic (PC) activity of the composites was investigated un- der UV irradiation. Furthermore, the photodegradation kinetics of formaldehyde was investigated using the composites as the cores of an air cleaner. A kinetics study showed that the reaction rate constants of the gas-phase PC reaction of formaldehyde were k = 0.576 mg'm3·min^-1 and K = 0.048 m3/mg.展开更多
Catalytic elimination of formaldehyde(HCHO) was investigated over Cu-Al_2O_3 catalyst at room temperature. The results indicated that no oxidation of HCHO into CO_2 occurs at room temperature, but the adsorption of H...Catalytic elimination of formaldehyde(HCHO) was investigated over Cu-Al_2O_3 catalyst at room temperature. The results indicated that no oxidation of HCHO into CO_2 occurs at room temperature, but the adsorption of HCHO occurs on the catalyst surface. With the increase of gas hourly space velocity(GHSV) and inlet HCHO concentration, the time to reach saturation was shortened proportionally. The results of the in situ DRIFTS, Density functional theory calculations and temperature programmed desorption(TPD) showed that HCHO was completely oxidized into HCOOH over Cu-Al_2O_3 at room temperature. With increasing the temperature in a flow of helium, HCOOH was completely decomposed into CO_2 over the catalyst surface, and the deactivated Cu-Al_2O_3 is regenerated at the same time. In addition, although Cu had no obvious influence on the adsorption of HCHO on Al_2O_3, Cu dramatically lowered the decomposition temperature of HCOOH into CO_2. It was shown that Cu-Al_2O_3 catalyst had a good ability for the removal of HCHO, and appeared to be promising for its application in destroying HCHO at room temperature.展开更多
The degradation of formaldehyde gas was studied using UV/TiO2/O3 process under the condition of continuous flow mode. The effects of humidity, initial formaldehyde concentration, residence time and ozone adding amount...The degradation of formaldehyde gas was studied using UV/TiO2/O3 process under the condition of continuous flow mode. The effects of humidity, initial formaldehyde concentration, residence time and ozone adding amount on degradation of formaldehyde gas were investigated. The experimental results indicated that the combination of ozonation with photocatalytic oxidation on the degradation of formaldehyde showed a synergetic action, e.g,, it could considerably increase decomposing of formaldehyde. The degradation efficiency of formaldehyde was between 73.6% and 79.4% while the initial concentration in the range of 1.84--24 mg/m^3 by O3/TiO2flJV process. The optimal humidity was about 50% in UV/TiO2/O3 processs and degradation of formaldehyde increases from 39.0% to 94.1% when the ozone content increased from 0 to 141 mg/m^3. Furthermore, the kinetics of formaldehyde degradation reaction could be described by Langmuir-Hinshelwood model. The rate constant k of 46.72 mg/(m^3.min) and Langmuir adsorption coefficient K of 0.0268 m^3/mg were obtained.展开更多
Metal-modified H-ZSM-5 has a high selectivity of aromatics in methanol to aromatics(MTA)reaction,which is often attributed to the metal promoting the aromatization of intermediate olefins.However,the effect of methano...Metal-modified H-ZSM-5 has a high selectivity of aromatics in methanol to aromatics(MTA)reaction,which is often attributed to the metal promoting the aromatization of intermediate olefins.However,the effect of methanol dehydrogenation on aromatics formation over these catalysts is rarely studied.Here,we report that HCHO,which is formed by methanol dehydrogenation over Zn/H-ZSM-5 prepared by Zn impregnation,can participate in the synthesis of aromatics.Methanol conversion can produce more aromatics than olefins(propylene or ethylene)conversion over Zn/H-ZSM-5,indicating the conventional MTA pathway including methanol-to-olefins and olefins-to-aromatics is not complete.Moreover,an MTA mechanism including the conventional pathway and the methanol and HCHO coupling pathway is systematically proposed.展开更多
Doping amine functional groups into SiO2/TiO2 films for enhancing the decomposition of formaldehyde has been investigated using the modified sol-gel method to prepare organic-inorganic hybrid photocatalysts via the co...Doping amine functional groups into SiO2/TiO2 films for enhancing the decomposition of formaldehyde has been investigated using the modified sol-gel method to prepare organic-inorganic hybrid photocatalysts via the co-condensation reaction of methyltrimethoxysilane (MTMOS) and amine functional groups, n-(2-Aminoethyl)-3-aminopropyl-trimethoxysilane (AEAPTMS) and 3-aminopropyl-trimethoxysilane (APTMS) were selected to study the effect of amine functional groups on the enhancement of formaldehyde adsorption and degradation under a UV irradiation process. Physicocbemical properties of prepared photocatalysts were characterized with nitrogen adsorption-desorption isotherms measurement, X-ray diffraction (XRD) and Fourier transform infrared (FT-IR) spectroscopy. The results indicated that the APTMS/SiO2/TiO2 film demonstrated a degradation efficiency of 79% superior to those of SiO2/TrO2 and AEAPTMS/SiO2/TiO2 films due to the synergetic effect of adsorption and photocatalytic properties. The APTMS/SiO2/TiO2 film can be recycled with about 7% decreasing of degradation efficiency after seven cycles.展开更多
基金supported by the National Natural Science Foundation of China(No.21774139)China,Key Research and Development Program of Shanxi Province,China(No,202102040201009)special fund of Beijing Key Laboratory of Clean Fuels and Efficient Catalytic Emission Reduction Technology and the Fund for Shanxi“1331 Project”.Thanks to Ningbo Kejiang Culture Sci.&Tech.Development Co.,Ltd.for the help in schematic drawing。
文摘Melamine formaldehyde foam(MFF)generates many poisonous chemicals through the traditional recycling methods for organic resin wastes.Herein,a high MFF degradation ratio of ca.97 wt.%was achieved under the mild conditions(160℃)in a NaOH–H2O system with ammelide and ammeline as the main degradation products.The alkaline solvent had an obvious corrosion effect for MFF,as indicated by scanning electron microscopy(SEM).The reaction process and products distribution were studied by Fourier-transform infrared spectroscopy(FTIR),X-ray photoelectron spectroscopy(XPS),and ^(13)C nuclear magnetic resonance(NMR).Besides,the MFF degradation products that have the similar chemical structures and bonding performances to those of melamine can be directly used as the raw material for synthesis of melamine urea-formaldehyde resins(MUFs).Moreover,the degradation system demonstrated here showed the high degradation efficiency after reusing for 7 times.The degradation process generated few harmful pollutants and no pre-or post-treatments were required,which proves its feasibility in the safe removal or recovery of waste MFF.
文摘Due to its ability to cause illnesses and discomfort even at low concentrations, formaldehyde pollution of indoor air poses a significant risk to human health. Sources of formaldehyde in indoor environments include textiles, paints, wallpapers, glues, adhesives, varnishes, and lacquers;furniture and wooden products like particleboard, plywood, and medium-density fiberboard that contain formaldehyde-based resins;shoe products;cosmetics;electronic devices;and other consumer goods like paper products and insecticides. According to the World Health Organisation, indoor formaldehyde concentrations shouldn’t exceed 0.1 mg/m<sup>3</sup>. The methods include membrane separation, plasma, photocatalytic decomposition, physisorption, chemisorption, biological and botanical filtration, and catalytic oxidation. Materials based on metal oxides and supported noble metals work as oxidation catalysts. Consequently, a paint that passively eliminates aldehydes from buildings can be developed by adding absorbents and formaldehyde scavengers to the latex composition. It will be crucial to develop techniques for the careful detection and removal of formaldehyde in the future. Additionally, microbial decomposition is less expensive and produces fewer pollutants. The main goal of future research will be to develop a biological air quality control system that will boost the effectiveness of formaldehyde elimination. The various methods of removing formaldehyde through paints have been reviewed here, including the use of mixed metal oxides, formaldehyde-absorbing emulsions, nano titanium dioxide, catalytic oxidation, and aromatic formaldehyde abating materials that can improve indoor air quality.
文摘This research focuses on the evaluation of diverse approaches for removing formaldehyde from indoor environments,which is a significant concern for indoor air quality.The study systematically examines physical,chemical,and biological methods to ascertain their effectiveness in formaldehyde mitigation.Physical methods,including air circulation and adsorption,particularly with activated carbon and molecular sieves,are assessed for their efficiency in various concentration scenarios.Chemical methods,such as photocatalytic oxidation using titanium dioxide and plasma technology,are analyzed for their ability to decompose formaldehyde into non-toxic substances.Additionally,biological methods involving plant purification and microbial transformation are explored for their eco-friendly and sustainable removal capabilities.The paper concludes that while each method has its merits,a combined approach may offer the most effective solution for reducing indoor formaldehyde levels.The study underscores the need for further research to integrate these methods in a practical,cost-effective,and environmentally sustainable manner,highlighting their potential to improve indoor air quality significantly.
基金the financial support from Dalian Institute of Chemical Physics (DMTO201604)Focus Area Innovation Team Support Plan of Dalian (2021RT03)+1 种基金National Natural Science Foundation of China (21878284)Regional Development Young Scholars of the Chinese Academy of Sciences。
文摘Membrane contactor is regarded as a promising method for reaction and process intensification. The feasibility of formaldehyde carbonylation to synthesize glycolic acid using polytetrafluoroethylene(PTFE)membrane contactor has been proved in our previous study. In this paper, the effect of membrane microstructure on process performance was further investigated. Three porous PTFE hollow fibers with different pore sizes and one polydimethylsiloxane(PDMS)/PTFE composite membrane with dense layer were fabricated for comparison. The physical and chemical properties of four membranes, including chemical composition, morphology, contact angle, liquid entry pressure, thermodynamic analysis and gas permeability, were systemically characterized. Experiments of formaldehyde carbonylation under different reaction conditions were conducted. The results indicated that the yield of glycolic acid increased with decreasing pore size for porous membranes, which was due to the improvement of wetting behavior. The dense layer of PDMS in composite hollow fiber could effectively prevent the solvent from entering membrane pores, thus the membrane exhibited the best performance. At reaction temperature of 120℃ and operation pressure of 3.0 MPa, the yield of glycolic acid was always higher than 90% as the mass ratio of trioxane and phosphotungstic acid increased from 0.2:1 to 0.8:1. The highest turnover frequency was up to 26.37 mol·g^(-1)·h^(-1). This study provided a reference for the understanding and optimization of membrane contactors for the synthesis of glycolic acid using solvent with low surface tension.
基金financially supported by the National Natural Science Foundation of China(Nos.52104156,52074351,52004330)the Science and Technology Innovation Program of Hunan Province,China(No.2021RC3125)the Natural Science Foundation of Hunan Province,China(No.2022JJ30714)。
文摘Rod milling sand(RMS)—a coarse sand aggregate—was recycled for cemented paste backfill(CPB)for the underground mined area at the Jinchuan nickel deposit,named rod milling sand-based cemented paste backfill(RCPB).The adverse effects of coarse particles on the transportation of CPB slurry through pipelines to underground stopes resulting in weakening of the stability of the backfill system are well known.Therefore,sulfonated naphthalene formaldehyde(SNF)condensate was used for the performance improvement of RCPB.The synergistic effect of solid content(SC),lime-to-sand ratio,and SNF dosage on the rheological and physicomechanical properties,including slump,yield stress,bleeding rate,uniaxial compressive strength(UCS),as well as mechanism analysis of RCPB,have been explored.The results indicate that the effect of SNF on RCPB performance is related to the SNF dosage,lime-to-sand ratio,and SC.The slump of fresh RCPB with 0.1wt%-0.5wt%SNF increased by 2.6%-26.2%,whereas the yield stress reduced by 4.1%-50.3%,indicating better workability and improved cohesiveness of the mix.The bleeding rate of fresh RCPB decreased first and then rose with the increase of SNF dosage,and the peak decrease was 67.67%.UCS of RCPB first increased and then decreased with the increase of SNF dosage.At the optimal SNF addition ratio of 0.3wt%,the UCS of RCPB curing for 7,14 and,28 d ages increased by 31.5%,28.4%,and 29.5%,respectively.The beneficial effects of SNF in enhancing the early UCS of RCPB have been corroborated.However,the later UCS increases at a slower rate.The research findings may guide the design and preparation of RCPB with adequate performance for practical applications.
基金the National Natural Science Foundation of China (NSFC,52070006)BeijingNova Program of Science and Technology (Z191100001119116).
文摘Formaldehyde(HCHO)has been identified as one of the most common indoor pollutions nowadays.Manganese oxides(MnO_(x))are considered to be a promising catalytic material used in indoor HCHO oxidation removal due to their high catalytic activity,low-cost,and environmentally friendly.In this paper,the progress in developing MnO_(x)-based catalysts for HCHO removal is comprehensively reviewed for exploring the mechanisms of catalytic oxidation and catalytic deactivation.The catalytic oxidation mechanisms based on three typical theory models(Mars-van-Krevelen,Eley-Rideal and Langmuir-Hinshelwood)are discussed and summarized.Furthermore,the research status of catalytic deactivation,catalysts’regeneration and integrated application of MnO_(x)-based catalysts for indoor HCHO removal are detailed in the review.Finally,the technical challenges in developing MnO_(x)-based catalysts for indoor HCHO removal are analyzed and the possible research direction is also proposed for overcoming the challenges toward practical application of such catalysts.
文摘The study characterized the curing behaviors of phenol formaldehyde(PF)resin under different vacuum degrees and explored the properties of 9-ply plywood panels hot-pressed under both vacuum and atmospheric conditions.The changes in core temperature and moisture content of the plywood mats during hot pressing were investigated as well.It was found that the gel times and gel temperatures of PF resin decreased with the increase of vacuum degree using a self-made device.FTIR spectra indicated the degree of polycondensation of hydroxymethyl gradu-ally increased with the increase in temperature.It was also observed that a higher degree of vacuum led to a slower polycondensation reaction rate of PF resin.During different hot-pressing processes,the bonding strengths in the innermost and uppermost gluelines of the vacuum hot-pressed plywood panels were up to 30%–50%higher than their counterparts of conventional hot-pressed products.A less difference in the bonding strengths between these two gluelines was also observed for vacuum hot-pressed products.In addition,the core of vacuum hot-pressed plywood was found to have a greater heating rate and higher temperature at thefinal stage of hot pressing,which was beneficial to cure the PF resin.The results from this study indicate a promising potential of introducing a vacuum during hot pressing to improve the quality and productivity of plywood products and provide a basis for adopting vacuum to hot press wood composites.
文摘Objective: The aim of this study was to compare the olfactory function between hairdressers exposed to formaldehyde and unexposed controls, as exposure to toxic agents is a potential cause of olfactory disorders in humans. Hairdressing professionals frequently encounter formaldehyde, a component found in hair products that are known to have various toxic effects on the human body, including alterations in the sense of smell. Methods: A total of 32 hairdressing volunteers exposed to formaldehyde and 32 non-exposed volunteers matched for age, sex, education and smoking status underwent the University of Pennsylvania Smell Identification Test (UPSIT<sup>®</sup>). Results: The findings demonstrated a decrease in UPSIT<sup>®</sup> olfactory test scores and a higher degree of olfactory loss among hairdressers exposed to formaldehyde (mean UPSIT<sup>®</sup> scores: 30.6 vs 35.1, p Conclusion: Occupational exposure of hairdressers to formaldehyde is associated with diminished olfactory function. Education approach and promotion of personal protective equipment usage should be encouraged.
文摘Objective: The aim of this study was to compare the olfactory function between hairdressers exposed to formaldehyde and unexposed controls, as exposure to toxic agents is a potential cause of olfactory disorders in humans. Hairdressing professionals frequently encounter formaldehyde, a component found in hair products that are known to have various toxic effects on the human body, including alterations in the sense of smell. Methods: A total of 32 hairdressing volunteers exposed to formaldehyde and 32 non-exposed volunteers matched for age, sex, education and smoking status underwent the University of Pennsylvania Smell Identification Test (UPSIT<sup>®</sup>). Results: The findings demonstrated a decrease in UPSIT<sup>®</sup> olfactory test scores and a higher degree of olfactory loss among hairdressers exposed to formaldehyde (mean UPSIT<sup>®</sup> scores: 30.6 vs 35.1, p Conclusion: Occupational exposure of hairdressers to formaldehyde is associated with diminished olfactory function. Education approach and promotion of personal protective equipment usage should be encouraged.
文摘For manufacturing low-formaldehyde emission particleboard from wheat straw and urea-formaldehyde (UF) resins using urea treatment for indoor environments, we investigated the influence of urea treatment on the formaldehyde emission, physical and mechanical properties of the manufactured particleboard. Wheat straws were treated at three levels of urea concentration (5%, 10%, 15%) and 95℃ as holding temperature. Wheat straw particleboards were manufactured using hot press at 180℃ and 3 MPa with two types of UF adhesive (UF-45, UF-91). Then the formaldehyde emission values, physical properties and mechanical properties were considered. The results show that the for- maldehyde emission value was decreased by increasing urea concentration. Furthermore, the results indicate that the specimens under urea treatment have better mechanical and physical properties compared with control specimens. Also specimens under urea treatment at 10% concentration and UF-91 type adhesive have the most optimum physical and mechanical strength.
文摘In this study Eucalyptus tannin (T) was isolated from outer bark of Eucalyptus trees;as sodium phenoxide salt and used as extender or copolymer into phenol formaldehyde (PF) resin at five percent (10, 20, 30, 40 and 50)% W/W. Tan-nin-phenol formaldehyde (TPF) and tannin formaldehyde-phenol formaldehyde (TFPF) resins that synthesized in this study were evaluated as adhesive material for cellulosic fibers by study the mechanical properties of the composite sheets .The results show that the substituting of (PF) with tannin at (10 –50)% W/W give resins with mechanical properties comparable or near to those of pure (PF) , where the tensile strength at break (Tb) ranging from 15.15 Mpa to 22.27 Mpa as compared with 17.6 Mpa for pure (PF);while the impact strength properties (Im) of composites sheets increased with increased the (T) percents which were about 5.16 KJ/m2 for (TPF – 10%) and 7.21 KJ/m2 for (TPF - 50%) .On the other hand modification of (T) to tannin formaldehyde resin (TF) appear less performance at the results of this study , this effect probably to low penetration of (TFPF) resins between the small voids of cellulose fibers when soaked it in resin solutions. In general the results of this study indicate that the Eucalyptus tannin can be used for par-tial substitution of (PF) to produce resins with feasible mechanical properties and can be used in some applications of (PF) resins.
基金grants from the SciTechnical Development Project of Shaanxi Province, China (2005K15-G2) Traditional Chinese Project of Shaanxi Province, China (2005024) Natural Science Foundation of Xi' an Jiaotong University (573026).
文摘Aim: To investigate the effect of formaldehyde (FA) on testes and the protective effect of vitamin E (VE) against oxidative damage by FA in the testes of adult rats. Methods: Thirty rats were randomly divided into three groups: (1) control; (2) FA treatment group (FAt); and (3) FAt + VE group. FAt and FAt + VE groups were exposed to FA by inhalation at a concentration of 10 mg/m^3 for 2 weeks. In addition, FAt + VE group were orally administered VE during the 2-week FA treatment. After the treatment, the histopathological and biochemical changes in testes, as well as the quantity and quality of sperm, were observed. Results: The testicular weight, the quantity and quality of sperm, the activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and glutathione (GSH) were significantly decreased whereas the level of malondialdehyde (MDA) was significantly increased in testes of rats in FAt group compared with those in the control group. VE treatment restored these parameters in FAt + VE group. In addition, microscopy with hematoxylin-eosin (HE) staining showed that seminiferous tubules atrophied, seminiferous epithelial cells disintegrated and shed in rats in FAt group and VE treatment significantly improved the testicular structure in FAt + VE group. Conclusion: FA destroys the testicular structure and function in adult rats by inducing oxidative stress, and this damage could be partially reversed by VE.
文摘The amine-functionalized mesoporous silica materials were prepared via the co-condensation reaction of tetraethoxysilane and three types of organoalkoxysilanes: 3-aminopropyl-trimethoxysilane, n-(2-aminoethyl)-3-aminopropyltrimethoxysilane, and 3-(2-(2- aminoehtylamino)ethylamino) propyl-trimethoxysilane. Cetyltrimethylammonium bromide was used as a template for forming pores, Specific surface area and pore volume of the amine-functionalized mesoporous silica materials were determined using surface area and pore size analyzer. Fourier transform infrared (FTIR) spectroscope was employed for identifying the functional groups on pore surface. In addition, the amine-functionalized mesoporous silica materials were applied as adsorbents for adsorbing formaldehyde vapor. FTIR spectra showed the evidence of the reaction between formaldehyde molecules and amine groups on pore surface of adsorbents. The equilibrium data of formaldehyde adsorbed on the adsorbents were analyzed using the Langmuir, Freundlich and Temkin isotherm. The sample functionalized from n-(2-aminoethyl)-3-aminopropyltrimethoxysilane showed the highest adsorption capacity owing to its amine groups and the large pore diameter.
文摘The present report evaluates the effects of formaldehyde (FA) exposure on peripheral lymphocytes by using heth genetic and immunological parameters. Twenty-three non-smoking students in the study had inhalation exposure to 0.508 ±0. 299 mg/m3 of FA for a Period of 8 weeks (3h × 3 times each week) during anatomy classes. As for composition of lymphocyte subsets after FA exposare,significant increase was found in the percentage of CD19(B cells), while sighficant decrease was observed in CD3(total T cells), CD4(T helper-inducer cells), and CD8(T cytotoxic-suppressior cells) with a P<0 .01. Increase in the ratio of T-helper-inducer cells to T-cytotoxic-suppressor cells (T4 / T8) was also observed with statistical sighcance after exposure (P < 0.001). In the meanwhile,no significant difference (P > 0 .05) was reported between lymphocyte prolifendion rate and sisterchromatid exchange (SCE) at the exposure level and duration. It is suggested that the lymphocyte subsets may be most susceptible to the effects of FA, though a single immunological endpoint is rarely related with pathophysiological interpretation.
基金financially supported by the National Natural Science Foundation of China (No. 50708037)the National Science Fund for Excellent Young Scholars of China (No. 51522402)+1 种基金the Science and Technology Research Projects in Zhengzhou (No. 141PPTGG388)the National Innovation and Entrepreneurship Training Program of the Undergraduate (No. 201610078034)
文摘Diatomite-based porous ceramics were adopted as carriers to immobilize nano-TiO2 via a hydrolysis-deposition technique. The thermal degradation of as-prepared composites was investigated using thermogravimetric-differential thermal analysis, and the phase and microstructure were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, and transmission electron microscopy. The results indicated that the carriers were encapsulated by nano-TiO2 with a thickness of 300-450 nm. The main crystalline phase of TiO2 calcined at 650~C was anatase, and the average grain size was 8.3 nm. The FT-IR absorption bands at 955.38 cm1 suggested that new chemical bonds among Ti, O, and Si had formed in the composites. The photocatalytic (PC) activity of the composites was investigated un- der UV irradiation. Furthermore, the photodegradation kinetics of formaldehyde was investigated using the composites as the cores of an air cleaner. A kinetics study showed that the reaction rate constants of the gas-phase PC reaction of formaldehyde were k = 0.576 mg'm3·min^-1 and K = 0.048 m3/mg.
基金The National Natural Science Foundation of China(No. 40275038)
文摘Catalytic elimination of formaldehyde(HCHO) was investigated over Cu-Al_2O_3 catalyst at room temperature. The results indicated that no oxidation of HCHO into CO_2 occurs at room temperature, but the adsorption of HCHO occurs on the catalyst surface. With the increase of gas hourly space velocity(GHSV) and inlet HCHO concentration, the time to reach saturation was shortened proportionally. The results of the in situ DRIFTS, Density functional theory calculations and temperature programmed desorption(TPD) showed that HCHO was completely oxidized into HCOOH over Cu-Al_2O_3 at room temperature. With increasing the temperature in a flow of helium, HCOOH was completely decomposed into CO_2 over the catalyst surface, and the deactivated Cu-Al_2O_3 is regenerated at the same time. In addition, although Cu had no obvious influence on the adsorption of HCHO on Al_2O_3, Cu dramatically lowered the decomposition temperature of HCOOH into CO_2. It was shown that Cu-Al_2O_3 catalyst had a good ability for the removal of HCHO, and appeared to be promising for its application in destroying HCHO at room temperature.
基金Project supported by the Science Project of Harbin City(No. H2001-12)the Youth Foundation of School of Municipal and Environmental Engineering in Harbin Institute of Technology(No. 01306914).
文摘The degradation of formaldehyde gas was studied using UV/TiO2/O3 process under the condition of continuous flow mode. The effects of humidity, initial formaldehyde concentration, residence time and ozone adding amount on degradation of formaldehyde gas were investigated. The experimental results indicated that the combination of ozonation with photocatalytic oxidation on the degradation of formaldehyde showed a synergetic action, e.g,, it could considerably increase decomposing of formaldehyde. The degradation efficiency of formaldehyde was between 73.6% and 79.4% while the initial concentration in the range of 1.84--24 mg/m^3 by O3/TiO2flJV process. The optimal humidity was about 50% in UV/TiO2/O3 processs and degradation of formaldehyde increases from 39.0% to 94.1% when the ozone content increased from 0 to 141 mg/m^3. Furthermore, the kinetics of formaldehyde degradation reaction could be described by Langmuir-Hinshelwood model. The rate constant k of 46.72 mg/(m^3.min) and Langmuir adsorption coefficient K of 0.0268 m^3/mg were obtained.
基金the financial support from the National Natural Science Foundation of China(Grant No.21978285,21991093,21991090)the“Transformational Technologies for Clean Energy and Demonstration”,Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA21030100)。
文摘Metal-modified H-ZSM-5 has a high selectivity of aromatics in methanol to aromatics(MTA)reaction,which is often attributed to the metal promoting the aromatization of intermediate olefins.However,the effect of methanol dehydrogenation on aromatics formation over these catalysts is rarely studied.Here,we report that HCHO,which is formed by methanol dehydrogenation over Zn/H-ZSM-5 prepared by Zn impregnation,can participate in the synthesis of aromatics.Methanol conversion can produce more aromatics than olefins(propylene or ethylene)conversion over Zn/H-ZSM-5,indicating the conventional MTA pathway including methanol-to-olefins and olefins-to-aromatics is not complete.Moreover,an MTA mechanism including the conventional pathway and the methanol and HCHO coupling pathway is systematically proposed.
基金supported by the Royal Golden Jubilee of Thailand Research Fundthe Department of Chemical Engineering at King Mongkut’s University of Technology Thonburi
文摘Doping amine functional groups into SiO2/TiO2 films for enhancing the decomposition of formaldehyde has been investigated using the modified sol-gel method to prepare organic-inorganic hybrid photocatalysts via the co-condensation reaction of methyltrimethoxysilane (MTMOS) and amine functional groups, n-(2-Aminoethyl)-3-aminopropyl-trimethoxysilane (AEAPTMS) and 3-aminopropyl-trimethoxysilane (APTMS) were selected to study the effect of amine functional groups on the enhancement of formaldehyde adsorption and degradation under a UV irradiation process. Physicocbemical properties of prepared photocatalysts were characterized with nitrogen adsorption-desorption isotherms measurement, X-ray diffraction (XRD) and Fourier transform infrared (FT-IR) spectroscopy. The results indicated that the APTMS/SiO2/TiO2 film demonstrated a degradation efficiency of 79% superior to those of SiO2/TrO2 and AEAPTMS/SiO2/TiO2 films due to the synergetic effect of adsorption and photocatalytic properties. The APTMS/SiO2/TiO2 film can be recycled with about 7% decreasing of degradation efficiency after seven cycles.
基金the financial support from the National Basic Research Program of China(No. 2009CB623200)the National Natural Science Foundation of China(No.50539040)the Scientific Research Foundation of Graduate School of Southeast University(No.YBJJ 0725).