Scaling and clogging treatment of aging tunnel drainage pipes in karst areas using eco-friendly acid agent

In karst areas,the drainage pipes of aging tunnels are prone to be clogged by precipitated carbonates,resulting in lining cracking and tunnel leaking.As a result,not only the driving safety will be deteriorated,but also the water pressure on the lining might also be elevated significantly.For the structural stability and service lifespan of old tunnels,it is of great importance to remove these precipitated carbonates in time.Traditional treatment methods are often destructive to some extent or not efficient enough.This study aims to experimentally develop an eco-friendly acid-based chemical cleaning method to remove carbonate precipitations efficiently.The proposed chemical cleaning agent is an aqueous solution with strong acidity,consisting of sulfamic acid,water,and additives.The factors affecting the cleaning efficiency include the acid solubility,temperature and flow rate of the cleaning agent,as well as additives.Elevating the solution temperature to 50
C or a flow rate of no less than 0.2 m/s can improve cleaning efficiency.Although the salt effect cannot work,1 wt%of polymaleic acid as a surfactant could further promote the cleaning rate.The cleaning efficiency will increase with the flow rate in a power function.The relatively low flow rate that improves the cleaning rate considerably can avoid highpressure-induced mechanical damage to tunnel drainpipes.The waste could be easily treated to acceptable levels using commercial sewage treatment products and can also be recycled in agriculture.With the chemical cleaning,the water pressure at the arch springing of the lining will reduce with the increased radius of transverse drainpipes in a power function.The proposed acid-based cleaning method,which is highly efficient,non-or low-destructive to aging tunnels,sufficiently safe for humans,and friendly enough to the environment,will offer a promising alternative to remove the precipitated carbonates in tunnel drainpipes efficiently.

Influence of Acid Treatment on Pore Structure and Fractal Characterization of a Tight Sandstone:A Case Study from Wudun Sag,Dunhuang Basin

In this study,X-ray diffraction,N_(2)adsorption(N_(2)A),and mercury intrusion(MI)experiments were used to investigate the influence of acid treatment on pore structure and fractal characterization of tight sandstones.The results showed that acid treatment generated a certain number of ink-bottle pores in fine sandstone,aggravated the ink-bottle effect in the sandy mudstone,and transformed some smaller pores into larger ones.After the acid treatment,both the pore volume in the range of 2–11 nm and 0.271–8μm for the fine sandstone and the entire pore size range for the sandy mudstone significantly increased.The dissolution of sandstone cement causes the fine sandstone particles to fall off and fill the pores;the porosity increased at first but then decreased with acid treatment time.The fractal dimension obtained using the Frenkel-Halsey-Hill model was positively correlated with acid treatment time.However,the total fractal dimensions obtained by MI tests showed different changes with acid treatment time in fine sandstone and sandy mudstone.These results provide good guiding significance for reservoir acidification stimulation.

Simultaneous removal of ammonium and phosphate by zeolite synthesized from coal fly ash as influenced by acid treatment

Zeolite synthesized from fly ash （ZFA） without modification is not efficient for the purification of NH4＋ and phosphate at low concentrations that occur in real effluents, despite the high potential removal capacity. To develop an effective technique to enhance the removal efficiency of ammonium and phosphate at low concentrations, ZFA was modified with acid treatment and the simultaneous removal of ammonium and phosphate in a wide range of concentration was investigated. It was seen that when compared with untreated ZFA, only the treatment by 0.01 mol/L of H2SO4 significantly improved the removal efficiency of ammonium at low initial concentrations. The behavior was well explained by the pH effect. Treatment by more concentrated H2SO4 led to the deterioration of the ZFA structure and a decrease in the cation exchange capacity. Treatment by 0.01 mol/L H2SO4 improved the removal efficiency of phosphate by ZFA at all initial P concentrations, while the treatment by concentrated H2SO4 （≥0.9 mol/L） resulted in a limited maximum phosphate immobilization capacity （PIC）. It was concluded that through a previous mild acid treatment （e.g. 0.01 mol/L of H2SO4）, ZFA can be used in the simultaneous removal of NH4＋ and P at low concentrations simulating real effluent.

Reduction in Activity/Gene Expression of Anthocyanin Degradation Enzymes in Lychee Pericarp is Responsible for the Color Protection of the Fruit by Heat and Acid Treatment

Heat and acid treatments were reported to be a promising substitute for SO2 fumigation in color protection of postharvest lychee （Litchi chinensis） fruits, but the mechanism was not clear. In the present study, hot water （70℃） dipping followed by immersion in 2% HC1 （heat-acid） substantially protected the red color of the fruit during storage at 25℃ and inhibited anthocyanin degradation while hot water dipping alone （heat） led to rapidly browning and about 90% loss in anthocyanin content. The pH values in the pericarp of the heat-acid treated fruit dropped to 3.2, while the values maintained around 5.0 in the heat-treated and control fruit. No significantly different pH values were detected among the arils of heat-acid, heat treated and control fruit. Heat-acid treatment dramatically reduced the activities of anthocyanin degradation enzyme （ADE）, peroxidase （POD） and polyphenol oxidase in the pericarp. A marked reduction in LcPOD gene expression was also detected in heat-acid treated fruit, in contrast, induction was found in heat treated fruit. The pericarp of heat-acid treated fruit exhibited significantly lower respiration rate but faster water loss than that of the untreated or heat treated fruit. Taken together, heat treatment triggered quick browning and anthocyanin loss in lychee fruit, while heat-acid treatment protected the fruit color by a great reduction in the activities/gene expression of anthocyanin degradation enzymes and acidification of lychee pericarp.

Analysis on the Variation Expression of Difficult-Dissolved-Proteins of Diapause Eggs After Activating by Acid Treatment

Using HCl to activate the diapause eggs is a traditional technique of artificial hatching applied in silkworm egg production. Its mechanism has not yet been clarified. This experiment explored the effect of HCl on the termination of diapause of silkworm eggs cold-stored for 45 days from the point of proteomes. Two-dimensional electrophoresis techniques and ESI- MS-MS were used to compare and analyze the variation expression of difficult-dissolved-proteins of diapause eggs coldstored for 45 days before and after acid treatment. Through analysis on the two-dimensional electrophoretogram, there were 296 dots before acid treatment and 302 after the treatment, respectively. Amongst them 265 dots were matchable. The matchability reached 88.6%. There were 31 specific protein dots before acid treatment and 37 after acid treatment, respectively. ESI-MS-MS analysis was conducted for two specific protein-rich dots which disappeared after acid treatment. The results indicated that the sequence of No. 1 protein dot had 55 amino acids＇ peptide matched with those of chorion protein （Bombyx mori）. While the sequence of No. 2 protein dot had only 15 amino acids＇ peptide matched with those of heat shock protein hsp 19.9 （Bombyx mori）, and it was presumed to be an unknown protein. The difficult-dissolvedproteins of diapause eggs have variation expression after acid treatment. Some proteins before and after acid treatment are changed in MW.

Catalytic performance improvement of volatile organic compounds oxidation over MnO_(x) and GdMnO_(3) composite oxides from spent lithium-ion batteries:Effect of acid treatment

In this work,cathode materials of spent lithium-ion ternary batteries are recovered and used as metal precursor to prepare multi-metal oxides MnO_(x)(SY)and GdMnO_(3)(SY)via combustion method and sol-gel method,respectively.Furthermore,a series of MnO_(x)(SY)-n and GdMnO_(3)(SY)-n(n=0.05,0.10,1.00,4.00,n represents the dilute HNO_(3) concentration)catalysts are fabricated by acid treatment of MnO_(x)(SY)and GdMnO_(3)(SY)samples and catalytic activities of oxygenated VOCs oxidation over all the prepared catalysts are investigated.Catalytic evaluation results show that acid-treated MnO_(x)(SY)-0.10 and GdMnO_(3)(SY)-0.05 samples perform the optimum VOCs removal efficiency respectively,which may be attributed to their obvious enhancement of physicochemical properties.In detail,Mn O_(x)(SY)-0.10 and GdMnO_(3)(SY)-0.05 samples exhibit the larger specific surface area,bigger amount of surface high-valence metal ions(Mn^(4+),Co^(3+),Ni^(3+)),more abundant adsorbed oxygen species and better low-temperature reducibility,which can play a crucial role in the significant improvement of VOCs oxidation.In situ DRIFTS results imply that the possible main intermediates are-OCO,-COO and-C-O species produced during VOCs oxidation.Possible by-products are further determined via TD/GC-MS analysis.

INFLUENCES OF ACID POST-TREATMENT ON THE MORPHOLOGY OF SOAP-FREE P(MMA-EA-MAA)PARTICLES PREPARED BY SEEDED EMULSION POLYMERIZATION

Soap-free poly（methyl methacrylate-ethyl acrylate-methacrylic acid） latex particles with narrow size distribution were synthesized by seeded emulsion polymerization, and the porous particles were created by a stepwise alkali/acid treatment method. Effects of acid treatment conditions on the particle morphology were investigated. Results show that one to three pores were formed inside most of particles after post-treatment. At pH 7.0, when the treatment temperature was lower than 70℃, the size of particles and the volume of pores remained almost unchanged, and these two values increased significantly when the temperature was higher than 70℃. Both the particle size and the pore volume decreased with the increase of initial pH value and treatment time in the acid treatment. As the pH was below 4.0 and the treatment time was longer than 180 min, the particles shrunk in size.

PREPARATION OF HOLLOW LATEX PARTICLES BY ALKALI-ACID TREATMENT

Hollow polymer latex particles were prepared by seeded emulsion polymerization. A seed latex consisting of styrene (St), butyl acrylate(BA) copolymer was first prepared, and seeded terpolymerization of St BA MA(methacrylic acid) were then carried out in the absence of surfactant. Final latex was treated by a two step treatment under alkaline and acidic conditions, thus, the particles with hollow structure were obtained. We discussed the effects of pH value, temperature and time in alkali and acid treatment processes on hollow structure within the polymer latex particles and amount of carboxylic group on particle surface. The results show that the hollow polymer latex particles with the largest hollow size can be obtained under a certain condition (pH12.5, 90°C, 3 h in alkali treatment stage and pH2.5, 85°C, 3 h in acid treatment stage).

Enhancing the crystalline degree of carbon nanotubes by acid treatment, air oxidization and heat treatment

Three approaches of treating carbon nanotubes (CNTs) including acid treatment, air oxidization and heat treatment at high temperature were studied to enhance the crystalline degree of carbon nanotubes. High temperature heat-treatment elevates the crystalline degree of carbon nanotubes. Acid treatment removes parts of amorphous carbonaceous matter through its oxidization effect. Air oxidization disperses carbon nanotubes and amorphous carbonaceous matter. The treatment of combining acid treatment with heat-treatment further elevates the crystalline degree of carbon nanotubes comparing with acid treatment or heat-treatment. The combination of the three treatments creates the thorough effects of enhancing the crystalline degree of carbon nanotubes.

THE EFFECT OF ACID TREATMENT ON THE STABILITY OF POLYMORPHS IN BETA ZEOLITE

The stability of beta zeollie in acid solution and the effect of acid treatment on the polymorphs in beta zeolite were studied. This zeolite is easily dealuminated by HCI treatment but its framework highly resistent to acidity.In β zeolite, polymorph A is less stable than polymorph B.The chirality of β zeolite can be modified by the method of acid treatment.

Corrosion inhibition of α,β-unsaturated carbonyl compounds on steel in acid medium

Corrosion inhibition of three α,β-unsaturated carbonyl compounds on N80 steel at high temperature and in concentrated acid medium was evaluated, and the inhibition mechanism was investigated. The results proved that both cinnamaldehyde and benzalacetone had an evident anticorrosion effect and could reduce the corrosion of steel effectively in acid medium, α,β-unsaturated carbonyl compounds with a benzene ring structure had good adsorption on steel surface. The experiments proved that polymerization of α,β-unsaturated carbonyl compounds on the steel surface at a high temperature and in concentrated acid medium resulted in a good corrosion inhibiting effect, which was attributed to the structures of α,β-unsaturated carbonyl compounds.

Electrochemical corrosion behavior of acid treated strip cast AM50 and AZX310 magnesium alloys in 3.5 wt.% NaCl solution

The influence of acid treatments on the surface morphology and electrochemical corrosion behavior of strip-cast AM50 and AZX310 alloys have been studied in the present investigation.The alloys were acid treated using H_(3)PO_(4)(AT-1),HF(AT-2)and HNO3(AT-3)for different treatment durations viz.,60,300 and 600 s.The acid treatments produced a surface layer consisting of corresponding magnesium salts of the acids and were confirmed from the X-ray diffraction(XRD),scanning electron microscopy(SEM)and energy dispersive X-ray analysis(EDAX).AT-1 treatment produced cracked and network porous morphology for AM50 and AZX310 alloys respectively andAT-3 treatment exhibited dense creaked surface layer formation while AT-2 does not produce any significant change in the morphology.Polarization studies revealed that,the acid treatment significantly altered the corrosion process by altering anodic and cathodic reaction rates of AM50 and AZX310 alloys.The HNO3(AT-3)treatment was effective compared to other treatments to control the corrosion rate in the studied treatment conditions.The surface morphology and chemical composition of surface layer produced during the treatment was correlated to explain the corrosion results.

Formaldehyde oxidation on Pd/USY catalysts at room temperature: The effect of acid pretreatment on supports

The complete catalytic oxidation of formaldehyde (HCHO) to CO_(2)and H_(2)O at room temperature is a green route for indoor HCHO removal.Zeolite is an excellent carrier material for HCHO oxidation due to its large surface area,intricate pores and high adsorption capacity.However,the zeolite-supported noble metal catalysts have currently shown relatively low activity especially at room temperature.In this work,we present a facile acid treatment strategy for zeolite catalysts to improve the hydroxyl concentration and further enhance their catalytic activity for HCHO oxidation.Activity tests illustrated that HCHO could be completely oxidized to CO_(2)and H_(2)O at a nearly 100%conversion rate with a weight hourly space velocity (WHSV) of 150,000 mL/(g·hr) at 25℃,when the support of Pd/USY catalysts was pretreated by hydrochloric acid with a concentration of 0.20 mol/L.The characterization results revealed that the active hydroxyl groups originated from the dealumination in the acid treatment play a key role in the HCHO oxidation reaction.The deduced reaction mechanism suggests that bridging hydroxyl groups may oxidize HCHO to dioxymethylene(DOM) species and terminal hydroxyl groups are responsible for the transformation of DOM groups to formate (HCOO) species.

A Study on Artificial Hatching of Chinese Bombyx mandarina Moore

Diapause eggs of Bombyx mandarina Moore from Wujiang, Jiangsu Province, China, were used to study the artificial hatching of B. mandarina Moore. The results showed that the highest hatchability was obtained by instant treatment with hydrochloric acid （HC1, specific gravity 1.065-1.075） for 5 rain under 46℃. After the B. mandarina eggs were cold stored at 5℃ for 40 days, the highest hatchability was obtained by treatment with HC1 （specific gravity 1.092） for 6 minutes under 47.8℃. For the B. mandarina eggs that were stored at 25℃ for 28 d and then cold-stored at 5℃ for 0-100 days, the highest hatchability was obtained by treatment with HCI （specific gravity 1.092） for 6 rain at 47.8℃. The longer the cold storage period, the higher was the hatchability. Acid treatment on diapause eggs of B. mandarina for 6 rains at 47.8℃ with hydrochloric acid （specific gravity 1.092） before hatching in spring could obviously shorten the hatching stage and increase the hatchability.

Enhancing the Surface Properties of a Bioengineered Anterior Cruciate Ligament Matrix for Use with Point-of-Care Stem Cell Therapy

We have previously developed a poly(L-lactic)acid(PLLA)bioengineered anterior cruciate ligament(ACL)matrix that has demonstrated enhanced healing when seeded with primary ACL cells prior to implantation in a rabbit model,as compared with the matrix alone.This suggests that improving cell adhesion on the matrix may beneficially affect the healing response and long-term performance of the bioengineered ACL matrix.One regenerative engineering approach involves enhancing the surface properties of the matrix to support cell adhesion and growth in combination with point-of-care stem cell therapy.Herein,we studied the cell adhesion properties of PLLA braided microfiber matrices enhanced through the physical adsorption of fibronectin and air plasma treatment.We evaluated the kinetics and binding efficiency of fibronectin onto matrices at three time points and three fibronectin concentrations.Incubating the matrix for 120 min in a solution of 25 lgmL1 fibronectin achieved the greatest binding efficiency to the matrix and cellular adhesion.Exposing the matrices to air plasma treatment for 5 min before fibronectin adsorption significantly enhanced the cell adhesion of rabbit bone marrow-derived mesenchymal stem cells(R-BMMSCs)24 h post cell seeding.Finally,cellular proliferation was monitored for up to 21 d,the matrices were exposed to air plasma treatment,and fibronectin adsorption was found to result in enhanced cell number.These findings suggest that exposure to air plasma treatment and fibronectin adsorption enhances the cellular adhesion of PLLA braided microfiber matrices and may improve the clinical efficacy of the matrix in combination with point-of-care stem cell therapies.

Fabrication of Micro/Nano-textured Titanium Alloy Implant Surface and Its Infl uence on Hydroxyapatite Coatings

We put forward a protocolcombining laser treatment and acid etching to obtain multiscale micro/nano-texture surfaces of titanium alloy implant.Firstly,the operationalparameters of the laser were optimized to obtain an optimum current.Secondly,the laser with the optimum operationalparameters was used to fabricate micro pits.Thirdly,multiple acid etching was used to clean the clinkers of micro pits and generate submicron and nanoscale structures.Finally,the bioactivity of the samples was measured in a simulated body fluid.The results showed that the micropits with a diameter of 150 μm and depth of 50 μm were built successfully with the optimized working current of 13 A.In addition,submicron and nanoscale structures,with 0.5-2 μm microgrooves and 10-20 nm nanopits,were superimposed on micro pits surface by multiple acid etching.There was thick and dense HA coating only observed on the multiscale micro/nano-textured surface compared with polished and micro-textured surface.This indicated that the multiscale micro/nano-texture surface showed better ability toward HA formation,which increased the bioactivity of implants.

Deposition of Carbon Particulates Surfaces on Zeolites by Electron-Beam Evaporation of Graphite

Disordered carbon particulates were deposited on the surface of natural acid treated zeolite through graphite evaporation by electron beam to improve adsorption properties of the porous material. This study focuses on the development of the new material and not on applications. The effect of acid treatment and carbon deposition on the physical properties of the natural material was investigated. The zeolites were characterized via spectroscopic and microscopic methods, thermal analysis, and gas sorption analysis. Analysis revealed that the surface area and volume increased by a factor of ten after the carbon-coating was deposited onto the zeolite surface and indicated that the Si/Al ratio was higher with the acid treated sample. The acid treatment promoted dealumination of the zeolite and increased overall surface area, whereas the carbon coating re-aluminated the zeolite while adding silica back to the main molecular framework, thus increasing crystallinity and thermal stability and further improving the high surface area produced by the acid treatment.

Oxygen vacancy engineering for tuning the catalytic activity of LaCoO_(3) perovskite

Herein, we attempted to engineer oxygen vacancies on the surface of LaCoO_(3) perovskite through simple post-treatments(acid or reductive thermal treatments). Acid treatment induces oxygen vacancies through the selective etching of the La cations, whereas thermal treatment in a reducing atmosphere generates oxygen vacancies by directly removing lattice oxygen. The characterization results confirm that the number of surface oxygen vacancies, which are crucial in various catalytic oxidation reactions,considerably increases in the LaCoO_(3) catalysts treated with acid or reducing gas. Acid treatment enriches the oxygen vacancies while maintaining the structure of the LaCoO_(3) catalysts, which can not be achieved through reductive thermal treatment. Therefore, the acid treatment is considered a promising technique for oxygen vacancy engineering of perovskite catalysts for tuning their catalytic activities. Furthermore,the catalytic activities of the posttreated LaCoO_(3) catalysts for CO oxidation were evaluated and are noted to be considerably better than those of the pristine LaCoO_(3) catalyst due to their abundant oxygen vacancies. Consequently, we conclude that the oxygen vacancies of perovskite catalysts can be effectively engineered via two simple methods and play a significant role in CO oxidation.

Modulating p-type doping of two-dimensional material palladium diselenide

The van der Waals heterostructures have evolved as novel materials for complementing the Si-based semiconductor technologies.Group-10 noble metal dichalcogenides(e.g.,PtS_(2),PtSe_(2),PdS_(2),and PdSe_(2))have been listed into two-dimensional(2D)materials toolkit to assemble van der Waals heterostructures.Among them,PdSe_(2) demonstrates advantages of high stability in air,high mobility,and wide tunable bandgap.However,the regulation of p-type doping of PdSe_(2) remains unsolved problem prior to fabricating p–n junction as a fundamental platform of semiconductor physics.Besides,a quantitative method for the controllable doping of PdSe_(2) is yet to be reported.In this study,the doping level of PdSe_(2) was correlated with the concentration of Lewis acids,for example,SnCl_(4),used for soaking.Considering the transfer characteristics,the threshold voltage(the gate voltage corresponding to the minimum drain current)increased after SnCl_(4) soaking treatment.PdSe_(2) transistors were soaked in SnCl_(4) solutions with five different concentrations.The threshold voltages from the as-obtained transfer curves were extracted for linear fitting to the threshold voltage versus doping concentration correlation equation.This study provides in-depth insights into the controllable p-type doping of PdSe_(2).It may also push forward the research of the regulation of conductivity behaviors of 2D materials.

Effect of Acid Treatment on Electrocatalytic Performance of PtNi Catalyst

In this paper,we describe the synthesis of the AC-PtNi/G catalysts with graphene as the carrier,via the alcohol reduction and the sulfuric acid treatment.The prepared catalysts were microscopically characterized by X-ray diffractometry(XRD),X-ray photoelectron spectroscopy(XPS),scanning electron microscopy(SEM),electron spectroscopy(EDAX),and transmission electron micros-copy(TEM).We tested the electrochemical performance of the prepared catalysts using an electrochemical workstation and in situ infrared spectroscopy(FTIR).The results showed that the acid-treated AC-PtNi/G catalysts had a more uniform dispersion and with the increased of treatment time,the particle size of the catalyst became smaller.And the electrocatalytic performance of the AC-PtNi/G-48h catalyst treated with sulfuric acid for 48 h was significantly better than that of the untreated PtNi/G catalyst.Its electrochemically active surface area was 76.63 m^(2)/g,and the peak current density value for catalytic oxidation of ethanol was 1218.83 A/g,which was 10 times that of ordinary commercial Pt/C catalyst.The steady-state current density value of 1100 s was 358.77 A/g,and it has excellent anti-CO toxicity performance.It was determined that a sulfuric acid treatment controlled catalyst particle size and increased the electrocatalytic activity of the catalytic oxidation of ethanol.