Research and development on mechanism of removal of indoor volatile organic compounds by plants

Background,aim,and scope Owing to the rapid development of modernisation and urbanisation,living standards have gradually improved.However,the widespread use of high-energy-consuming indoor appliances and furniture has made indoor environments a primary environmental problem affecting human health.Sick building syndrome(SBS)and building-related illness(BRI)have occurred,and indoor air conditions have been extensively studied.Common indoor pollutants include CO,CO_(2),volatile organic compounds(VOCs)(such as the formaldehyde and benzene series),NOx(NO and NO_(2)),and polycyclic aromatic hydrocarbons(PAHs).VOCs have replaced SO_(2)as the“The Fourteenth Five-Year Plan”urban air quality assessment new indicators.Indoor VOCs can cause diseases such as cataract,asthma,and lung cancer.To protect human health,researchers have proposed several indoor air purification technologies,including adsorption,filtration,electrostatic dust removal,ozonation,and plant purification.However,each technology has drawbacks,such as high operating costs,high energy consumption,and the generation of secondary waste or toxic substances.Plant degradation of VOCs as a bioremediation technology has the characteristics of low cost,high efficiency,and sustainability,thereby becoming a potential green solution for improving indoor air quality.This study introduces the research status and mechanism of plant removal of indoor VOCs and provides an experimental basis and scientific guidance for analysing the mechanism of plant degradation of pollutants.Materials and methods This study reviews studies on the harm caused by indoor pollutants to human health and related sources,mainly investigating the degradation of indoor formaldehyde,BTEX(benzene,toluene,ethylbenzene,and xylene)plant mechanisms,and research results.Results Plants can remove VOCs via stomatal and non-stomatal adsorption,interfoliar microbial,rhizosphere microbial,and growth media.Benzene,toluene,and xylene(BTX)are adsorbed by pores,hydroxylated into fumaric acid,and then removed into CO_(2) and H_(2)O by TCA.Formaldehyde enters plant leaves through the stomata and epidermal waxy substances and is adsorbed.After the two steps of enzymatic oxidation,formic acid and CO_(2) are generated.Finally,it enters the Calvin cycle and removes glucose and other nontoxic compounds.Discussion The non-stomatal degradation of VOCs can be divided into adsorption by cuticular wax and active adsorption by plant surface microorganisms.The leaf epidermal waxy matter content and the lipid composition of the epidermal membrane covering the plant surface play important roles in the non-stomatal adsorption of indoor air pollutants.The leaf margin of a plant is an ecological environment containing various microbial communities.The endophytic and inoculated microbiota in plant buds and leaves can remove VOCs(formaldehyde and BTEX).Formaldehyde can be directly absorbed by plant leaves and converted into organic acids,sugars,CO_(2) and H_(2)O by microbes.Bioremediation of indoor VOCs is usually inefficient,leading to plant toxicity or residual chemical substance volatilisation through leaves,followed by secondary pollution.Therefore,plants must be inoculated with microorganisms to improve the efficiency of plant degradation of VOCs.However,the effectiveness of interfoliar microbial removal remains largely unknown and several microorganisms are not culturable.Therefore,methods for collecting,identifying,and culturing microorganisms must be developed.As the leaf space is a relatively unstable environment,the degradation of VOCs by rhizosphere microorganisms is equally important,and formaldehyde is absorbed more by rhizosphere microorganisms at night.The inoculation of bacteria into the rhizosphere improves the efficiency of plants in degrading VOCs.However,most of these studies were conducted in simulation chambers.To ensure the authenticity of these conclusions,the ability of plants to remove indoor air pollutants must be further verified in real situations.Conclusions Plant purification is an economical,environment-friendly,and sustainable remediation technology.This review summarises the mechanisms of VOC plant degradation and presents its limitations.Simultaneously,it briefly puts forward a plant selection scheme according to different temperatures,light,and specific VOCs that can be absorbed to choose the appropriate plant species.However,some studies have denied the purification effect of plants and proposed that numerous plants are required to achieve indoor ventilation effects.Therefore,determining the ability of plants to remove indoor VOCs requires a combination of realistic and simulated scenarios.Recommendations and perspectives Plants and related microorganisms play an important role in improving indoor air quality,therefore,the effect of plants and the related microorganisms on improving indoor air quality must be studied further and the effect of plants on indoor VOCs will be the focus of future research.

省悟:休闲拯救文明

人类文明陷入危机,亟需拯救;回归文明的"人明"本质,凸显休闲的省悟功能,可以拯救文明。休闲省悟就是人在休闲中的反省和觉悟,反省是人生修养的重要途径,觉悟是创新思维的活水源头;省悟作为休闲的顶级体验,具有闲暇性、心灵性、反身性、创造性等特点,有助于发现人性及生命的意义和价值,有助于调整生活方式、改善幸福观,促进文明发展的物本模式向人本模式转变。休闲及其省悟对于我们拯救文明具有其他方式不可替代的作用,它可扭转物质文明的"物化"趋势,促使社会大众在政治上掌握自己的命运,推动精神文明的价值取向走向"去物化",促使社会文明更加和谐、和睦、和平,促使生态文明成为"生态人明",实现真正的"天人合一"。

Influence of sulfation on CeO_2-ZrO_2 catalysts for NO reduction with NH_3

CeO2‐ZrO2 (CeZr) and sulfated CeO2‐ZrO2 (S‐CeZr) catalysts were prepared for the selective catalytic reduction of NO with NH3. The CeZr catalysts exhibited higher activity at low temperatures (< 200°C) and lower activity at high temperatures (> 200 °C) than the S‐CeZr catalysts. The sulfation ofCeZr was studied in terms of surface acidity, redox properties and NO adsorption‐desorption bytemperature‐dependent experiments and in situ infrared spectroscopy. S‐CeZr displayed high concentrationsof acidic sites and increased surface acidities, but poor reducibility compared with CeZr.The high acidity of S‐CeZr was attributed to the presence of Br?nsted acid sites, arising mainly fromthe surface sulfates. Because the surface was covered with sulfate species, S‐CeZr showed lower NOadsorption and weaker oxidation ability than CeZr. The adsorption of NH3 on the Br?nsted acid sites restricted the reaction with NO at low temperatures, but the selective catalytic reduction cycle occurred easily at relatively low temperatures (150 °C), and the weakly bound nitrite was partially activated on the S‐CeZr catalyst at relatively high temperatures (300 °C). The catalytic mechanisms for the CeZr and S‐CeZr catalysts at 150 and 300 °C were also studied.

S-scheme Sb2WO6/g-C3N4 photocatalysts with enhanced visible-light-induced photocatalytic NO oxidation performance

Normal photocatalysts cannot effectively remove low-concentration NO because of the high recombination rate of the photogenerated carriers.To overcome this problem,S-scheme composites have been developed to fabricate photocatalysts.Herein,a novel S-scheme Sb2WO6/g-C3N4 nanocomposite was fabricated by an ultrasound-assisted method,which exhibited excellent performance for photocatalytic ppb-level NO removal.Compared with the pure constituents of the nanocomposite,the as-prepared 15%-Sb2WO6/g-C3N4 photocatalyst could remove more than 68%continuous-flowing NO(initial concentration:400 ppb)under visible-light irradiation in 30 min.The findings of the trapping experiments confirmed that•O2^–and h+were the important active species in the NO oxidation reaction.Meanwhile,the transient photocurrent response and PL spectroscopy analyses proved that the unique S-scheme structure of the samples could enhance the charge separation efficiency.In situ DRIFTS revealed that the photocatalytic reaction pathway of NO removal over the Sb2WO6/g-C3N4 nanocomposite occurred via an oxygen-induced route.The present work proposes a new concept for fabricating efficient photocatalysts for photocatalytic ppb-level NO oxidation and provides deeper insights into the mechanism of photocatalytic NO oxidation.

Kinetics and thermodynamics of cyanide removal by ZnO@NiO nanocrystals

ZnO,NiO and ZnO@NiO nanocrystals were successfully synthesized and characterized by FTIR,XRD and SEM methods.The average particles sizes of ZnO,NiO and ZnO@NiO were32,50and48nm,respectively.The nanocrystals were examined assensors for cyanide removal.The cyanide sensing test revealed that,compared with the pure ZnO,NiO,the ZnO@NiO nanocrystalsexhibited highly improved sensing performances.The ZnO@NiO nano crystals were found to have better capacity for iron cyanidethan sodium cyanide.The effects of significant parameters such as contact time,pH(2-12),nanocrystal dose(0.02-0.4g)andcyanide concentration(5-50mg/L)on the removal of cyanide by nanocrystals were explored.At an optimum pH<5,over90%removal of20mg/L cyanide was obtained for nanocrystal dose of0.2g after30min contact time for iron cyanide by ZnO@NiOnano crystals.Cyanide removal was followed by pseudo second order kinetic model for ZnO@NiO nano crystals(k2=4.66×10-2andR2=0.999).The values of standard entralpy change of7.87kJ/mol and standard free energy change of-18.62kJ/mol at298K suggestthe adsorption of cyanide on nanocrystals is an endothermic and spontaneous process.ZnO@NiO nanocrystal is an efficient sensorfor removal of cyanide from water and wastewater.

Performance evaluation of a modified step-feed anaerobic/anoxic/oxic process for organic and nutrient removal

A pilot scale modified step-feed process was lmproved to increase nutrient/N ano P） ano organic removal operations from municipal wastewater. It combined the step-feed process and a method named ＂University of Cape Town （UCT）＂. The effect of nutrient ratios and inflow distribution ratios were studied. The highest uptake efficiency of 95% for chemical oxygen demand （COD） has been achieved at the inflow distribution ratio of 40/35/25. However, maximum removal efficiency obtained for total nitrogen （TN） and phosphorus at 93% and 78%, respectively. The average mixed liquor suspended solids （MLSS） was 5500 mg·L- 1. In addition, convenient values for dissolved oxygen （DO） concentration, and pH were obtained throughout different stages. The proposed system was identified to be an appropriate enhanced biological nutrient removal process for wastewater treatment plants owing to relatively high nutrient removal, sturdy sludge settle ability and COD removal.

Removal and transformation of organic matter during soil-aquifer treatment

This study investigated the removal and transformation of organic matter through laboratory-scale soil-aquifer treatment (SAT) soil columns over a 110-day period. Reductions in total organic carbon (TOC), dissolved organic carbon (DOC), biodegradable dissolved organic carbon (BDOC), nonbiodegradable dissolved organic carbon (NBDOC) and absorbance of ul-traviolet light at 254 nm (UV-254) averaged 71.46%, 68.05%, 99.31%, 33.27% and 38.96% across the soil columns, respectively. DOC/TOC ratios increased slightly with depth while BDOC/DOC ratios showed a converse trend. DOC exiting the soil-column system contained only a very small biodegradable fraction. SAT decreased the concentration of DOC present in feed water but increased its aromaticity, as indicated by specific ultraviolet light absorbance (SUVA), which increased by 50%～115% across the soil columns, indicating preferential removal of non-aromatic DOC during SAT. Overall, laboratory-scale SAT reduced triha-lomethane formation potential (THMFP), although specific THMFP increased. THMFP reduction was dominated by removal in chloroform. All samples exhibited a common general relationship with respect to weight: chloroform>dichlorobromomethane >dibromochloromethane>bromoform.

AOF1 is a histone H3K4 demethylase possessing demethylase activity-independent repression function

LSD1 （KDM1 under the new nomenclature） was the first identified lysine-specific histone demethylase belonging to the flavin-dependent amine oxidase family. Here, we report that AOF1 （KDM1B under the new nomenclature）, a mammalian protein related to LSD1, also possesses histone demethylase activity with specificity for H3K4mel and H3K4me2. Like LSD1, the highly conserved SWIRM domain is required for its enzymatic activity. However, AOF1 differs from LSD1 in several aspects. First, AOF1 does not appear to form stable protein complexes containing histone deacetylases. Second, AOF1 is found to localize to chromosomes during the mitotic phase of the cell cycle, whereas LSD1 does not. Third, AOF1 represses transcription when tethered to DNA and this repression activity is independent of its demethylase activity. Structural and functional analyses identified its unique N-terminal Zf-CW domain as essential for the demethylase activity-independent repression function. Collectively, our study identifies AOF1 as the second histone demethylase in the family of flavin-dependent amine oxidases and reveals a demethylase-independent repression function of AOF1.

Photo‐catalyzed sequential dearomatization/carboxylation of benzyl o‐halogenated aryl ether with CO_(2) leading to spirocyclic carboxylic acids

Photo‐catalyzed tandem dearomatization/carboxylation of benzyl o‐halogenated aryl ether with CO_(2) was achieved,which affords spirocyclic carboxylic acids under mild conditions.The reaction has good functional group tolerance with high yields.Mechanism studies indicate that the transformation was realized via intramolecular radical addition and nucleophilic addition.

Generation and transformation of ROS on g-C_3N_4 for efficient photocatalytic NO removal:A combined in situ DRIFTS and DFT investigation

Understanding the performance of reactive oxygen species(ROS)in photocatalysis is pivotal for advancing their application in environmental remediation.However,techniques for investigating the generation and transformation mechanism of ROS have been largely overlooked.In this study,considering g‐C3N4 to be a model photocatalyst,we have focused on the ROS generation and transformation for efficient photocatalytic NO removal.It was found that the key to improving the photocatalysis performance was to enhance the ROS transformation from·O2^-to·OH,elevating the production of·OH.The ROS directly participate in the photocatalytic NO removal and tailor the rate‐determining step,which is required to overcome the high activation energy of the intermediate conversion.Using a closely combined experimental and theoretical method,this work provides a new protocol to investigate the ROS behavior on g‐C3N4 for effective NO removal and clarifies the reaction mechanism at the atomic level,which enriches the understanding of ROS in photocatalytic environmental remediation.

Localized dissolution initiated at single and clustered intermetallic particles during immersion of Al-Cu-Mg alloy in sodium chloride solution

Aiming at understanding how intermetallic phases response when AA2024-T3 aluminium alloy is exposed to chloridecontainingaqueous medium, scanning electron microscopy was employed to provide morphological information on alloy surfacebefore and after corrosion testing. Energy dispersive X-ray spectroscopy was carried out to determine compositional change inintermetallic particles. Atomic force microscopy was used to examine topographical variation introduced by the reactions ofintermetallic phases. Transmission electron microscopy combined with ultramicrotomy was carried out on dealloyed Al2CuMgparticles and their periphery region. It is found that dealloyed Al2CuMg particles exhibited porous, polycrystalline structurecomprised of body-centred cubic copper particles with sizes of 5 to 20 nm. Aluminium matrix started to trench in the periphery ofAl2CuMg particles at the early stage of dealloying. Development of trenching in Al.Cu.Fe.Mn.（Si） particle’s periphery was notuniform and took longer time to initiate than Al2CuMg dealloying. Localized corrosion at a cluster of Al2CuMg and Al2Cu particleswas mainly associated with Al2CuMg particles.

Electrochemical treatment of COD in biologically pretreated coking wastewater using Ti/RuO2-IrO2 electrodes combined with modified coke

The electrochemical treatment of COD contained in biologically pretreated coking wastewater treated by a three-dimensional electrode system with modified coke as the particle electrode was investigated. And the electrochemical perromance of the coke modified with various active components was studied. The results show that the coke modified with Fe（NO3）2 has the lowest energy consumption and higher COD removal rate under the same condition, and the modified coke has better surface characteristics for the purpose of this study. In addition, the kinetic constant was also calculated. The study shows that the three-dimensional electrode system with Fe （NO3）z-modified coke can give a satisfactory solution in biologically pretreated coking wastewater.

Removal atrazine using two anion-exchange resins supported nanohydrous metal-oxide particle

Hydrous iron oxide and hydrous aluminum oxide were loaded successfully onto a polymeric adsorbent(D301) to modify adsorbing materials(HIOD301 and HAOD301). The adsorptive equilibrium of atrazine was investigated in an aquatic environment using HIOD301 and HAOD301 under different experimental conditions. The results indicated that both HIOD301 and HAOD301 showed good adsorption capacities for atrazine at p H 4. The Langmuir and Freundlich isotherm equations were used to study the interactions between the adsorbate and adsorbent.The adsorption kinetics of atrazine at different concentrations was well described in terms of a pseudosecond-order equation in regard to the correlation coefficients and adsorption capacity. The removal percentages of atrazine for HIOD301 and HAOD301 were still more than 95% in the presence of sodium chloride.

Multi-pollutants simultaneous removal from flue gas

The multi-stages humidifier semi-dry flue gas cleaning technology, the CRS plasma flue gas cleaning technology and oxidative additive flue gas cleaning technology were investigated for multi-pollutants removal. The semi-dry flue gas cleaning technology using multi-stages humidifier and additive can improve oxidation and absorption, and it can achieve high multi-pollutants removal efficiency. The CRS discharge can produce many OH radicals that promote NO oxidation. Combining NaOH absorption can achieve high deSO2 and deNO, efficiencies. It is fit for the reconstruction of primary wet flue gas desulfurization （WFGD）. In addition, using NaClO2 as additive in the absorbent of WFGD can obtain very high removal efficiency of SO2 and NOx.

COD Removal Efficiencies of Some Aromatic Compounds in Supercritical Water Oxidation

Some aromatic compounds, phenol, aniline and nitrobenzene, were oxidized in supercritical water. It was experimentally found that the chemical oxygen demand (COD) removal efficiency of these organic compounds can achieve a high level more than 90% in a short residence time at temperatures high enough. As temperature, pressure and residence time increase, the COD removal efficiencies of the organic compounds would all increase. It is also found that temperature and residence time offer greater influences on the oxidation process than pressure. The difficulty in oxidizing these three compounds is in the order of nitrobenzene ＞ aniline ＞ Phenol. In addition, it is extremely difficult to oxidize aniline and nitrobenzene to CO2 and H2O at the temperature lower than 873.15 K and 923.15 K, respectively. Only at the temperature higher than 873.15 K and 923.15 K, respectively, the COD removal efficiencies of 90% of aniline and nitrobenzene can be achieved.

Demethylation of FANCF gene may be a potential treatment through inhibiting the proliferation of cervical cancer

Objective: The aim of the study was to explore the effect of demethylating agent 5-Aza-2'-deoxycytidine (5-ADC) on expression of Fanconi anemia complementation group F (FANCF) gene and the proliferation of cervical cancer cells, to observe cell's sensitivity to chemotherapeutic drug taxol, and to explore the antitumor effect of 5-ADC as well as the new treatment of cervical cancer. Methods: Cervical cancer cell lines SiHa (FANCF gene full-methylated) and Hela (unmethylated) were treated with 5-ADC. We used the methylation-specific PCR (MSP), reverse transcription-polymerase chain reaction (RT-PCR) and Western blot to detect the FANCF methylation, mRNA and protein respectively. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was used to detect the proliferation of cells. The cytotoxicity of taxol was measured by flow cytometer. The nude mice bearing SiHa was used to observe the effect of 5-ADC in vivo. Results: Inhibition of DNA promoter methylation by 5-ADC reactivated the expression of FANCF mRNA and protein in SiHa cells, consistent with decreased growth speed and increased taxol resistance. These results were proven in experiments in vivo. Conclusion: The 5-ADC probably become a potential treatment drug through inhibiting the proliferation of cervical cancer cells in taxol-resistant patients.

Molecular modeling of alkaloids bouchardatine and orirenierine binding to sirtuin-1(SIRT1)

Objective Bouchardatine(1)is a β-indoloquinazoline alkaloid isolated from the plant Bouchardatia neurococca,acting as a modulator of adipogenesis and lipogenesis,and as an anticancer agent.The natural product functions as an activator of proteins adenosine 5’-monophosphate(AMP)-activated protein kinase(AMPK)and sirtuin 1(SIRT1).We used molecular modeling to investigate the SIRT1-binding capacity of compound 1 and various structural analogues,such as orirenierine A(2)and orirenierine B(3)isolated from the medicinal plant Oricia renieri.Methods We investigated the binding to human SIRT1(hSIRT1)of 25 natural products including theβ-indoloquinazoline alkaloids 1−3 and analogues,in comparison with the reference product sirtinol(R and S isomers).A sirtinol binding model was elaborated starting from the closed and open state conformations of the catalytic domain of hSIRT1(PDB structures 4KXQ and 4IG9).For each compound bound to SIRT1,the empirical energy of interaction(ΔE)was calculated and compared to that of sirtinol.Results In our model,compound 1 was found to bind modestly to the sirtinol site of SIRT1.In contrast,the presence of a phenolic OH group at position 7 on the quinazolinone moiety conferred a much higher binding capacity.Compound 2 provided SIRT1 protein complexes as stable as those observed with sirtinol.The replacement of the hydroxy substituent(2)with a methoxy group(3)reduced the SIRT1 binding capacity.Other SIRT1-binding natural products were identified,such as the alkaloids orisuaveolines A and B.Structure-binding relationships were discussed.Conclusion The study underlines the capacity of β-indoloquinazoline alkaloids to interact with SIRT1.This deacetylase enzyme could represent a molecular target for the alkaloid 2.This compound merits further attention for the design of drugs active against SIRT1-dependent pathologies.

Microbial community study in a petrochemical industry wastewater treatment system by PCR-DGGE

To improve the efficiency of petrochemical wastewater purification, the relationship between bacterial community structure and pollutants loading/degrading rates in A/O process for petrochemical wastewater treatment was investigated by denaturing gradient gel eleetrophoresis （DGGE） of the 16S rRNA gene fragments amplified by polymerase chain reaction （PCR）. Results show that while the influent COD and NH4^＋ -N concentrations are 425.92 -560 mg/L and 64 - 100 mg/L respectively, the corresponding average concentrations of the effluent are 160 mg/L and 55 mg/L, which are 1. 6 and 3.6 times more than the national standards respectively. It demonstrates that the performance of pollutants removal process is inefficient. The analysis of PCR-DGGE profile indicates that the bacterial community structure of the activated sludge in A/O system is species-rich but unstable, and the highest and the lowest similarity coefficients are 36% and 6. 25% respectively, which shows that remarkable community structure evolution exists in the system. The variation of bacterial community structure and pollutants loading influences the removal efficiency of pollutants obviously, and relatively stable com- munity structure leads to the stable operational performance of biological wastewater treatment system.

Advances in Dearomative Carboxylation of Aromatic Compounds with Carbon Dioxide

Dearomative carboxylation of aromatic compounds with carbon dioxide(CO_(2))could be utilized for the synthesis of cyclic carboxylative frameworks.The dearomative carboxylation exhibits advantages such as reconstitution molecular spatial structure,environmental friendliness,mild conditions,high yield,and high selectivity,and is of significant importance in pharmaceutical synthesis and natural product chemistry.The recent advancements in the dearomative carboxylation of aromatics with CO_(2) are summarized,including elucidation of the reaction characteristics and the scope of substrates via transition-metal catalysis,photoredox catalysis,and electropromoted chemistry.

Magnetite/Reduced Graphene Oxide Nanocomposites： One Step Solvothermal Synthesis and Use as a Novel Platform for Removal of Dye Pollutants

A simple one step solvothermal strategy using non-toxic and cost-effective precursors has been developed to prepare magnetite/reduced graphene oxide （MRGO） nanocomposites for removal of dye pollutants. Taking advantage of the combined benefits of graphene and magnetic nanoparticles, these MRGO nanocomposites exhibit excellent removal efficiency （over 91% for rhodamine B and over 94% for malachite green） and rapid separation from aqueous solution by an external magnetic field. Interestingly, the performance of the MRGO composites is strongly dependent on both the loading of Fe304 and the pH value. In addition, the adsorption behavior of this new adsorbent fits well with the Freundlich isotherm and the pseudo-second-order kinetic model. In further applications, real samples--including industrial waste water and lake water--have been treated using the MRGO composites. All the results demonstrate that the MRGO composites are effective adsorbents for removal of dye pollutants and thus could provide a new platform for dye decontamination.