Citric and Oxalic Acids Effect on Pb and Zn Uptake by Maize and Winter Wheat

A pot experiment was conducted to investigate the influence of citric and oxalic acids effect on Pb and Zn uptake by corn and winter wheat. The experiment was employed with citric acid (CA) applied at 3 rates (0, 1.5 and 3.0 mmol kg-1 soil), oxalic acid (OA) at 3 rates (0, 1.5 and 3.0mmol kg-1 soil) and citric acid combined with oxalic acid (1.5 mmol citric acid combined with 1.5 mmol oxalic acid kg-1). Two types of soil were chose in the experiment. One was collected from the agricultural soil near a battery-recycling factory in Anhui province, China (site A) and the other was collected from a Pb-Zn mine residues in Hunan province, China (site B). The results showed that soil pH varied with the different treatment of citric and oxalic acids. However, there were no differences in all the treatments. 3.0mmol CA kg-1 soil addition significantly increased the concentrations of the CaCI2-extractable Pb and Zn and other treatments have no significantly increased. The highest shoot concentrations of Pb and

Recovery of Li, Ni, Co and Mn from spent lithium-ion batteries assisted by organic acids: Process optimization and leaching mechanism

The proper recycling of spent lithium-ion batteries(LIBs)can promote the recovery and utilization of valuable resources,while also negative environmental effects resulting from the presence of toxic and hazardous substances.In this study,a new environmentally friendly hydro-metallurgical process was proposed for leaching lithium(Li),nickel(Ni),cobalt(Co),and manganese(Mn)from spent LIBs using sulfuric acid with citric acid as a reductant.The effects of the concentration of sulfuric acid,the leaching temperature,the leaching time,the solid-liquid ratio,and the reducing agent dosage on the leaching behavior of the above elements were investigated.Key parameters were optimized using response surface methodology(RSM)to maximize the recovery of metals from spent LIBs.The maxim-um recovery efficiencies of Li,Ni,Co,and Mn can reach 99.08%,98.76%,98.33%,and 97.63%.under the optimized conditions(the sulfuric acid concentration was 1.16 mol/L,the citric acid dosage was 15wt%,the solid-liquid ratio was 40 g/L,and the temperature was 83℃ for 120 min),respectively.It was found that in the collaborative leaching process of sulfuric acid and citric acid,the citric acid initially provided strong reducing CO_(2)^(-),and the transition metal ions in the high state underwent a reduction reaction to produce transition metal ions in the low state.Additionally,citric acid can also act as a proton donor and chelate with lower-priced transition metal ions,thus speeding up the dissolution process.

Green Chemistry of Cellulose Acetate Membrane Plasticized by Citric Acid and Succinonitrile for Lithium-Ion Battery Application

Commercial lithium-ion batteries(LIBs)use polyolefins as separators.This has led to increased research on separators composed of renewable materials such as cellulose and its derivatives.In this study,the ionic conductivity of cellulose acetate(CA)polymer electrolyte membranes was enhanced via plasticization with citric acid and succinonitrile.The primary objective of this study was to evaluate the effectiveness of these plasticizers in improving cellulose-based separator membranes in LIBs.CA membranes were fabricated using solution casting technique and then plasticized with various concentrations of plasticizers.The structural,thermal,and electrochemical properties of the resulting membranes were characterized using Fourier Transform infrared(FTIR)spectroscopy,X-Ray Diffraction(XRD),Differential Scanning Calorimetry(DSC),Thermogravimetric Analysis(TGA),and Electrochemical Impedance Spectroscopy(EIS).The FTIR and XRD results confirmed the successful incorporation of citric acid and succinonitrile into the polymer matrix,while the TGA analysis demonstrated the enhanced thermal stability of the plasticized membranes.The shift in the glass transition temperature was determined by DSC analysis.Most notably,the EIS results revealed a significant increase in ionic conductivity,achieving a maximum of 2.7×10^(-5) S/cm at room temperature.This improvement was attributed to the effect of plasticizers,which facilitated the dissociation of lithium salts and increase the mobility of the lithium ions.The ionic conductivities of plasticized CA membranes are better than those of unmodified CA membranes and commercially available Celgard separator membranes:4.7×10^(-6) and 2.1×10^(-7) S/cm,respectively.These findings suggest that citric acid and succinonitrile are effective plasticizers for cellulose acetate membranes,making them promising substitutes for commercial polyolefin separators in LIB applications.

Kinetics of titanium leaching with citric acid in sulfuric acid from red mud

The recovery of titanium with citric acid in sulfuric acid from red mud was put forward to strengthen acid leaching efficiency.The main factors on the recovery of titanium such as citric acid addition,sulfuric acid concentration,leaching temperature,time and liquid-to-solid ratio were studied.The kinetics analysis of titanium leaching from red mud was deeply investigated.The results show that the citric acid could increase the recovery of titanium and decrease the consumption of sulfuric acid.The recovery of titanium was increased from 65% to 82% and the consumption of sulfuric acid was decreased by about 30% with using 5% citric acid.The dissolution of perovskite,brookite,and hematite in red mud could easily be dissolved using citric acid.The acid leaching process was controlled by internal diffusion of shrinking core model（SCM） and the correlation coefficient was above 0.98.The apparent rate constant was increased from 0.0012 to 0.0019 with 5% citric acid at 90 °C.The apparent activation energy of titanium leaching decreased from 39.77 k J/mol to 34.61 k J/mol with 5% citric acid.

Citric Acid Accumulation in an Alkali_tolerant Plant Puccinellia tenuiflora Under Alkaline Stress

The accumulation of citric acid and associated correlative strain indexes were investigated in the seedlings of Puccinellia tenuiflora (Griseb.) Scribn. et Merr. stressed with 0-175 mmol/L Na 2CO 3. The results showed that the citric acid accumulation is a specific physiological respond of this plant to alkali_stress. On the contrary, the citric acid content decreased slightly in this plant stressed with 0-400 mmol/L neutral salt NaCl. The accumulation of citric acid increased with increasing strength of alkali_stress, the citric acid content increased gently when the strength was lower than 100 mmol/L Na 2CO 3, but increased obviously when the strength was higher than 100 mmol/L Na 2CO 3. The citric acid rapidly accumulated at early alkali_stress, an obvious raise can be mensurated after 4 h. About 48 h after treatment, the amount of citric acid accumulated nearly reached the maximum. In various parts of P. tenuiflora seedlings alkali_stressed for 144 h, the order of citric acid content from high to low is: old leaf, mature leaf, old leaf sheath, young leaf sheath, young stem, old stem, and young leaf. In the mature leaf, the citric acid content gradually increased with increasing strength of alkali_stress, while the citric acid content increased sharply in old leaf and sheath just for strength higher than 125 mmol/L. There was little change of citric acid content in stem, but no change in young leaf. The results of the experiment showed that citric acid was outstanding among accumulated organic acid caused by alkali_stress. The contribution of other organic acids was negligible.

Effect of citric acid on microstructure and electrochemical characteristics of high voltage anodized alumina film formed on etched Al Foils

Aluminum capacitor foils with a tunnel etch structure were reacted with boiling water and then anodized at 530 V in boric acid solution or boric acid＋citric acid mixed solution.The microstructure and crystallinity of the resulting anodized film were examined by TEM and XRD.The special capacitance,resistance and withstanding voltage of the film were explored with electrochemical impedance spectroscopy（EIS）,LCR meter and small-current charging.The results show that the high voltage anodized oxide film consists of an inner layer with high crystallinity and an outer layer with low crystallinity.However,the crystallinity of the film formed in boric acid＋citric acid mixed solution is higher than that of the film formed in only boric acid solution,leading to an increase in film＇s field strength and special capacitance.Meanwhile,there are more defects from phase transformation in the out layer of the film formed in boric acid＋citric acid mixed solution than in that of film formed in only boric acid solution,leading to a decrease in film＇s resistance and withstanding voltage.

Corrosion protection of AZ91D magnesium alloy by a cerium-molybdenum coating-The effect of citric acid as an additive

In order to improve the corrosion resistance of AZ91D magnesium alloy,a coating was formed by a potentiostatic technique from a solutions containing Ce(NO_(3))_(3),Na_(2)MoO_(4)and citric acid(H_(3)Cit).The degree of corrosion protection achieved was evaluated in simulated physiological solution by monitoring the open circuit potential,polarization techniques and electrochemical impedance spectroscopy(EIS).Surface analysis techniques(SEM,EDS,X-ray diffraction and X-ray photoelectron spectroscopy(XPS))were used for coating characterization.The film is mainly composed by cerium and molybdenum oxides and magnesium oxides and hydroxides.The obtained results show that the corrosion resistance of the coated electrodes has been increased significantly.This improvement in the anticorrosive performance is in part due to the corrosion inhibition properties of H_(3)Cit.

Effects of Citric Acid on Hydration Process and Mechanical Properties of Thermal Decomposed Magnesium Oxychloride Cement

In order to make full use of salt lake magnesium resources and improve the strength of the thermal decomposed magnesium oxychloride cement （TDMOC）, the effects of citric acid on the hydration process and mechanical properties of TDMOC was studied. The hydration heat release at initial 24 h and strengths at 3, 7, and 28 days of TDMOC specimens were conducted. The hydration products and paste microstructure were analyzed by XRD, FT-IR and SEM, respectively. The results showed that citric acid can not only reduce the 24 h hydration heat release and delay the occurring time of second peak of TDMOC, but also produce more 5Mg（OH）z.MgC12.SH20 and less Mg（OH）2 in hydration process of TDMOC. More perfect and slender crystals were observed in the microstructure of the TDMOC pastes with citric acid. The results demonstrated that citric acid as an additive of TDMOC can decrease the hydration heat release and increase the compressive strength and flexural strength of TDMOC. The possible mechanism for the strength enhancement was discussed.

Investigation on leaching of malachite by citric acid

Leaching of an oxidized copper ore containing malachite, as a new approach, was investigated by an organic reagent, citric acid. Sulfuric acid is the most common reagent in the leaching of oxide copper ores, but it has several side effects such as severe adverse impact on the environment. In this investigation, the effects of particle size, acid concentration, leaching time, solid/liquid ratio, temperature, and stirring speed were optimized. According to the experimental results, malachite leaching by citric acid was technically feasible. Optimum leaching conditions were found as follows： the range of particle size, 105-150 μm; acid concentration, 0.2 M; leaching time, 30 min; solid/liquid ratio, 1：20 g/mL; temperature, 40℃; and stirring speed, 200 r/min. Under the optimum conditions, 91.61% of copper was extracted.

Wheat straw biochar amendment suppresses tomato bacterial wilt caused by Ralstonia solanacearum: Potential effects of rhizosphere organic acids and amino acids

Complex interactions based on host plant, rhizosphere microorganisms and soil microenvironment are presumed to be responsible for the suppressive properties of biochar against soil-borne diseases, although the underlying mechanisms are not well understood. This study is designed to evaluate the efficacy of biochar amendment for controlling tomato bacterial wilt caused by Ralstonia solanacearum, and to explore the interactions between biochar-induced changes in rhizosphere compound composition, the pathogen and tomato growth. The results showed that biochar amendment decreased disease incidence by 61–78% and simultaneously improved plant growth. The positive ‘biochar effect' could be associated with enhanced microbial activity and alterations in the rhizosphere organic acid and amino acid composition. Specifically, elevated rhizosphere citric acid and lysine, but reduced salicylic acid, were induced by biochar which improved microbial activity and rendered the rhizosphere unsuitable for the development of R. solanacearum. In addition, nutrients which were either made more available by the stimulated microbial activity or supplied by the biochar could improve plant vigor and potentially enhance tomato resistance to diseases. Our findings highlight that biochar's ability to control tomato bacterial wilt could be associated with the alteration of the rhizosphere organic acid and amino acid composition, however, further research is required to verify these ‘biochar effects' in field conditions.

Maximizing the exploitation of phosphogypsum wastes using soaking technique with citric acid, recovering rare-earth and residual phosphate contents

Phosphogypsum(PG), the main by-product of phosphoric acid production industries, is considered one of the most important secondary sources of rare earth elements(REEs). The current study focuses on the recovery of REEs content and the residual phosphate content existing in the PG with preserving on the CaSO_(4)skeleton to be used in other various applications. These attainments are carried out using citric acid leaching process via soaking technique. Several dissolution parameters for REEs using citric acid were studied, including soaking time, soaking temperature, citric acid concentration, solid-to-liquid ratio, and recycling of the citrate leaching solutions in the further REEs dissolution experiments. The best-operating conditions were 14 d of soaking time, 7.5% citric acid concentration, and the solid-toliquid ratio of 1/5 at ambient temperature. About 79.57% dissolution efficiency of REEs was achieved using the optimal conditions. Applying four soaking stages by mixing different fresh PG samples with the same citrate solution sequentially, cumulative dissolution efficiency for REEs was found to be 64.7% under optimal soaking conditions. REEs were recovered using Dowex 50X8 resin from citrate solutions with 96% extraction efficiency. Dissolution kinetics proved the pseudo-first-order nature, reversible reactions, and two activation energies for all REEs.

Extraction of cobalt from laterite ores by citric acid in presence of ammonium bifluoride

Citric acid was used to selectively extract cobalt from limonite-type laterite ores in the presence of ammonium bifluoride.The results show that ammonium bifluoride enhances the leaching of cobalt by citric acid,and 84.5% cobalt is extracted from a laterite ore containing 0.13% Co when leached at ambient temperature for 2 h with 30 g/L citric acid and 10 g/L ammonium bifluoride.Pyrolusite is reduced by citric acid during leaching,cobalt intergrown with which is liberated and subsequently chelated by the citric acid.The extraction of cobalt is enhanced in the presence of ammonium bifluoride because the matrix of silicate minerals is destroyed by ammonium bifluoride and the adsorbed cobalt is subsequently liberated.

Novel neuroprotective and hepatoprorective effects of citric acid in acute malathion intoxication

Objective: To study the effect of citric acid given alone or combined with atropine on brain oxidative stress, neuronal injury, liver damage, and DNA damage of peripheral blood lymphocytes induced in the rat by acute malathion exposure. Methods: Rats were received intraperitoneal(i.p.) injection of malathion 150 mg/kg along with citric acid(200 or 400 mg/kg, orally), atropine(1 mg/kg, i.p.) or citric acid 200 mg/kg+atropine 1 mg/kg and euthanized 4 h later. Results: Malathion resulted in increased lipid peroxidation(malondialdehyde) and nitric oxide concentrations accompanied with a decrease in brain reduced glutathione, glutathione peroxidase(GPx) activity, total antioxidant capacity(TAC) and glucose concentrations. Paraoxonase-1, acetylcholinesterase(ACh E) and butyrylcholinesterase activities decreased in brain as well. Liver aspartate aminotransferase and alanine aminotransferase activities were raised. The Comet assay showed increased DNA damage of peripheral blood lymphocytes. Histological damage and increased expression of inducible nitric oxide synthase(i NOS) were observed in brain and liver. Citric acid resulted in decreased brain lipid peroxidation and nitric oxide. Meanwhile, glutathione, GPx activity, TAC capacity and brain glucose level increased. Brain ACh E increased but PON1 and butyrylcholinesterase activities decreased by citric acid. Liver enzymes, the percentage of damaged blood lymphocytes, histopathological alterations and i NOS expression in brain and liver was decreased by citric acid. Meanwhile, rats treated with atropine showed decreased brain MDA, nitrite but increased GPx activity, TAC, ACh E and glucose. The drug also decreased DNA damage of peripheral blood lymphocytes, histopathological alterations and i NOS expression in brain and liver. Conclusions: The study demonstrates a beneficial effect for citric acid upon brain oxidative stress, neuronal injury, liver and DNA damage due to acute malathion exposure.

CROSS-LINKING OF CHITOSAN WITH GLUTARALDEHYDE IN THE PRESENCE OF CITRIC ACID——A NEW GELLING SYSTEM

The procedure for preparing a new type of uniform and porous chitosan gel from citric acid medium is described. Its swelling behavior in different media was compared with those of the gels prepared by other methods. The ultrastructure of the xerogel prepared from citric acid was characterized using electron microscopy (SEM).

Removal of Cd(Ⅱ)and Pb(Ⅱ)from soil through desorption using citric acid:Kinetic and equilibrium studies

The desorption test was conducted to evaluate the desorption behavior of Pb(Ⅱ)and Cd(Ⅱ)using citric acid.The influential factors that were considered included initial Pb(Ⅱ),Cd(Ⅱ)contamination levels in soil,concentration of citric acid,reaction time,soil pH value and ionic strength.The test results indicated that the desorption was a rapid reaction(less than 6 h),and the removal percentages of Cd(Ⅱ)and Pb(Ⅱ)increased with the increasing contamination levels,concentration of citric acid and the addition of Na^+,Ca^(2+),Na^+, Cl~– and the chelating of organic ligands.

Corrosion resistance of Mg-Al-LDH steam coating on AZ80 Mg alloy:Effects of citric acid pretreatment and intermetallic compounds

In this study,the effects of intermetallic compounds(Mg_(17)Al_(12)and Al_(8)Mn_(5))on the Mg-Al layered double hydroxide(LDH)formation mechanism and corrosion behavior of an in-situ LDH/Mg(OH)_(2)steam coatings on AZ80 Mg alloy were investigated.Citric acid(CA)was used to activate the alloy surface during the pretreatment process.The alloy was first pretreated with CA and then subjected to a hydrothermal process using ultrapure water to produce Mg-Al-LDH/Mg(OH)_(2)steam coating.The effect of different time of acid pretreatment on the activation of the intermetallic compounds was investigated.The microstructure and elemental composition of the obtained coatings were analyzed using FE-SEM,EDS,XRD and FT-IR.The corrosion resistance of the coated samples was evaluated using different techniques,i.e.,potentiodynamic polarization(PDP),electrochemical impedance spectrum(EIS)and hydrogen evolution test.The results indicated that the CA pretreatment significantly influenced the activity of the alloy surface by exposing the intermetallic compounds.The surface area fraction of Mg_(17)Al_(12)and Al_(8)Mn_(5)phases on the surface of the alloy was significantly higher after the CA pretreatment,and thus promoted the growth of the subsequent Mg-Al-LDH coatings.The CA pretreatment for 30 s resulted in a denser and thicker LDH coating.Increase in the CA pretreatment time significantly led to the improvement in corrosion resistance of the coated AZ80 alloy.The corrosion current density of the coated alloy was lower by three orders of magnitude as compared to the uncoated alloy.

Synthesis of Mesoporous, Nanocrystalline Lanthanum Phosphate in the Presence of Citric Acid and Stearic Acid

Lanthanum phosphate was prepared in the presence of citric acid and stearic acid under methanolic conditions at pH 4.5 and pH 7, respectively. The samples obtained were intensively characterized using X-ray diffraction, nitrogen adsorption-desorption isotherm study, transmission electron microscopy （TEM）, thermal gravimetric and differential thermal analysis, and Fourier transform infrared （FTIR） analysis . The as-synthesized samples prepared at pH 4.5 showed lamellar mesostruroned form with high crystallinity. Results showed that the pore size and pore volume changed when the materials were prepared under different pH conditions. Morphology of the samples was observed by using TEM, which showed that the samples possessed relatively small particles closely packed together. The as-synthesized samples were investigated using FTIR, and the mesopore formation mechanism was discussed.

Fluorescence Properties of Eu^(3+)/Gd^(3+)/Citric Acid Mixed Complexes Doping in Silicon Rubber Matrix

Series of doped rare earth compiexes-EuxGd(1-x) (CA)3·nH2O (CA = citric acid) were synthesized. Some characterizations were taken for these complexes. The experimental results shows that the doped rare earth complexes have the best fluorescence property when the ratio of Eu and Gd is from 0.7 to 0.3. Silicon rubber-based composites were prepared by mechanical blending the EuxGd(1-x) (CA)3·nH2O and silicon rubber. Then, the fluorescent property of the composites was studied. It is found that the fluorescence intensity of the composites increase linearly with the contents of the rare earth complexes increasing.

Novel Ni/CeO_2-Al_2O_3 composite catalysts synthesized by one-step citric acid complex and their performance in catalytic partial oxidation of methane

A series of novel Ni/CeOe-Al2O3 composite catalysts were synthesized by one-step citric acid complex method, The as-synthesized catalysts were characterized by N2 physical adsorption/desorption, X-ray diffraction （XRD）, Fourier transform infrared （FT-IR） spectroscopy, hydrogen temperature-programmed reduction （Hz-TPR）, X-ray photoelectron spectroscopy （XPS） and thermogravimetry analysis （TGA）. The effects of nickel content, calcination and reaction temperatures, gas hourly space velocity （GHSV） and inert gas dilution of N2 on their performance of catalytic partial oxidation of methane （CPOM） were investigated. Catalytic activity test results show that the highest methane conversion （〉85%）, the best selectivities to carbon monoxide （〉87%） and to hydrogen （〉95%）, the excellent stability and perfect Hz/CO ratio （2.0） can be obtained over Ni/CeO2-Al2O3 with 8 wt% Ni content calcined at 700 ℃ under the reaction condition of 750 ℃, CH4/O2 ratio of 2 ： 1 and gas hourly space velocity of 12000 mL.h-1 .g-1. Characterization results show that the good catalytic performance of this composite catalyst can be contributed to its large specific surface area （~108 m2.g-1）, small crystallite size, easy reducibility and low coking rate.

Pediatric bowel preparation: Sodium picosulfate, magnesium oxide, citric acid vs polyethylene glycol, a randomized trial

BACKGROUND Bowel preparation in children can be challenging.AIM To describe the efficacy, safety, and tolerability of sodium picosulfate, magnesium oxide, and citric acid(SPMC) bowel preparation in children.METHODS Phase 3, randomized, assessor-blinded, multicenter study of low-volume, divided dose SPMC enrolled children 9-16 years undergoing elective colonoscopy. Participants 9-12 years were randomized 1:1:1 to SPMC ? dose × 2, SPMC 1 dose × 2, or polyethylene glycol(PEG). Participants 13-16 years were randomized 1:1 to SPMC 1 dose × 2 or PEG. PEG-based bowel preparations were administered per local protocol. Primary efficacy endpoint for quality of bowel preparation was responders(rating of ‘excellent' or ‘good') by modified Aronchick Scale. Secondary efficacy endpoint was participant's tolerability and satisfaction from a 7-item questionnaire. Safety assessments included adverse events(AEs) and laboratory evaluations.RESULTS 78 participants were randomized, 48 were 9-12 years, 30 were 13-16 years. For the primary efficacy endpoint in 9-12 years, 50.0%, 87.5%, and 81.3% were responders for SPMC ? dose × 2, SPMC 1 dose × 2, and PEG groups, respectively. Responder rates for 13-16 years were 81.3% for SPMC 1 dose × 2 and 85.7% for PEG. Overall, 43.8% of participants receiving SPMC 1 dose × 2 reported it was ‘very easy' or ‘easy' to drink, compared with 20.0% receiving PEG. Treatment-emergent AEs were reported by 45.5% of participants receiving SPMC 1 dose × 2 and 63.0% receiving PEG.CONCLUSION SPMC was an efficacious and safe for bowel preparation in children 9-16 years, with comparable efficacy to PEG. Tolerability for SPMC was higher compared to PEG.