ENVIRONMENTAL POLLUTION
·
2024
·
IF 7.6
Ruihan Xiong,Caixiang Zhang,Hanxiang Xiong,Shuxin Huang,Jiasen Li
Glyphosate as an effective broad-spectrum herbicide is frequently detected in various water and soil resources. Given the ubiquity of β-MnO 2 and δ-MnO 2 colloids in groundwater and soil, the abiotic removal of glyphosate by MnO 2 colloids was investigated. β-MnO 2 colloids exhibited superior glyphosate removal efficiency, up to 37%, compared to 21% for δ-MnO 2 colloids at a pH of 4.0. Glyphosate removal involved simultaneous adsorption and oxidation process , identified by HRTEM , NH 3 -TPD, XPS , LC-MS, FTIR analyses and the occurrence of aminomethylphosphonic acid (AMPA) and Mn 2+ . Moreover, adsorption dominated the removal of glyphosate by two MnO 2 colloids. The solution pH had a substantial effect on glyphosate removal. Co-existing ions in the solution, such as carbonate (CO 3 2− ), phosphate (Na 2 HPO 4 , NaH 2 PO 4 ) and humic acid (HA), were also found to impede glyphosate removal. Phosphate, in particular, exhibited a strong competitive effect for adsorption sites on both MnO 2 colloids. Of them, the removal of glyphosate by β-MnO 2 colloids was more prone to occur due to its higher specific surface area , abundant oxygen vacancies , and moderate acid sites. However, δ-MnO 2 colloids presented a stronger oxidation capacity than that of β-MnO 2 colloids due to the quicker generation rate of Mn 2+ . Finally, AMPA was the same products by two MnO 2 colloids in the oxidation process, revealing the degradation pathway based on the cleavage of C–N bond. Therefore, by comparing kinetics and mechanisms of glyphosate removal by β- and δ-MnO 2 colloids, this study improves us better understanding for the behavior of glyphosate in the environment.
研究领域:
环境科学
·
化学
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产品关联
DOI
PubMed
高影响因子
INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
·
2020
·
IF 5.162
Junjie Hu,Chaozhang Huang,Anda Gong,Huanle Chen,Shilin Liu,Bin Li,Yan Li
In the present study, we prepared cinnamaldehyde (CA) conjugated chitosan-stabilized emulsions (CSCAEs), and the influence of pH on their properties and lipolysis behavior was investigated. Compared to the emulsions stabilized by chitosan itself (CSEs), CSCAEs had better stability against pH during storage. As pH increased from 2.5 to 6.25, the viscosity and modulus of CSCAEs increased. However, when pH shifted from 6.25 to 6.5, emulsion showed lower viscosity and modulus. Confocal laser scanning microscopy results demonstrated that oil droplets still kept intact and individually distributed, and chitosan homogenously covered on the oil droplets at low pH conditions (pH 2.5, 4.0). At higher pH conditions (pH 5.0, 5.5), a few chitosan aggregates on the oil droplets were observed. At pH 6.0 and 6.25, the compact gel network structure was formed. At pH 6.5, some void was found among the chitosan gel network. In vitro simulated digestion experiments presented that pH had no significant effect on the lipolysis process of emulsions. When the oil content varied from 10% to 50%, emulsions still kept good stability against pHs, but the lipolysis extent after digestion decreased. This knowledge provides a strategy for improving stability of chitosan-stabilized emulsion against harsh pH conditions.
研究领域:
食品科学
·
生物化学
✓ 已验证
DOI
高影响因子
GREEN CHEMISTRY
·
2016
·Vol. 18
·期 17
·4725-4732
·
IF 8.506
Ting Lu,Muge Niu,Yucui Hou,Weize Wu,Shuhang Ren,Fan Yang
The preparation of formic acid (FA) by catalytic oxidation of sustainable biomass is of significant conceptual and practical interest, because FA is an important chemical and is now produced from non-sustainable fossil fuel. In this work, we found that a binary catalyst of Keggin-type heteropoly acid H5PV2Mo10O40 + H2SO4 was efficient in oxidizing biomass cellulose to FA using oxygen as an oxidant in aqueous solution. In the oxidation, the pH of the aqueous solutions plays a key role, and a decrease in pH improves the transformation. Cellulose was transformed to FA with conversions from 60% to 100% and FA yields from 28% to 61% (based on the carbon atoms in the feedstock) after 5 min of reaction at 180 °C, using H2SO4 as an additive to decrease the pH from 1.79 to 0.56. The influences of the pH on both the catalyst and the reaction pathway were discussed. By decreasing the pH, the oxidation potential and electron affinity were increased due to the formation of protonated H5PV2Mo10O40 and VO2+ species, favoring the reduction of the catalyst and oxidation of the substrate. A reaction pathway for the generation of products was proposed, and the influence of the pH on the reaction pathway was also discussed.
研究领域:
化学工程
·
生物质能
·
催化科学
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产品关联
DOI
高影响因子
JOURNAL OF ENVIRONMENTAL SCIENCE AND HEALTH PART A-TOXIC/HAZARDOUS SUBSTANCES & ENVIRONMENTAL ENGINEERING
·
2020
·
IF 1.724
Liang Xu,Fenglian Fu
In order to treat selenium pollution, the study presents the use of potassium ferrate (K2FeO4) as an environmentally friendly agent for in situ removal of Se(IV) from aqueous media. Batch experiments were carried out to evaluate the influences of various factors including dosage of K2FeO4, ex-situ and in-situ adsorption, initial pH, and adsorption isotherms. The results showed that increasing dosage of K2FeO4 benefited the removal of total selenium with the efficiency up to 97.0% and Se(IV) removal significantly depended on pH, and as the pH increases, the decrease in Se(IV) adsorption efficiency is a general trend of pH dependence. The X-ray powder diffraction, Fourier transformed infrared spectrometer and high-resolution X-ray photoelectron spectroscopy analysis indicated that Se(IV) was removed from the aqueous solution by adsorbing on the surface of the decomposition products of K2FeO4 which are ferric oxide nanoparticles, and the selenium adsorbed on the generated ferric oxide nanoparticles existed in the forms of Se(IV) and Se(VI). Se(IV) and Se(VI) were adsorbed to the decomposition products of K2FeO4 by forming an inner-sphere complexes and an outer-sphere complexes, respectively.
研究领域:
环境科学
·
化学工程
✓ 已验证
DOI
高影响因子
SCIENCE OF THE TOTAL ENVIRONMENT
·
2019
·
IF 5.589
Boyin Yan,Zhiquan Liu,Ying Liu,Rui Huang,Yongpeng Xu,Dongmei Liu,Fuyi Cui,Wenxin Shi
β- N -Methylamino- l -alanine (BMAA), a new cyanobacterial toxin , is found in different aquatic ecosystems worldwide and is to threaten the human nervous system. Therefore, it is important for water plants to develop feasible methods to counter the effects of BMAA. In this study, the removal of BMAA by chlorine, as well as its intermediate products, at different pH values and the mechanism of pH on the removal BMAA were investigated. The results showed that the chlorination of BMAA is in accordance with the second-order kinetics model. The reaction rate of chlorinated BMAA increased with the increase in the concentration of chlorine. The pH of the solution significantly affected the reaction rate. The apparent kinetic constant ( k app ) decreased from 6.00 × 10 3 M − 1 ·min − 1 to 35.5 M − 1 ·min − 1 when the pH increased from 4.5 to 9 in the chlorine concentration of 32.23 μM. It is probable that the species distribution and proportion of BMAA and chlorine at different pH values were the main causes of this phenomenon. Additionally, the chlorination reaction consisted of four elementary reactions and hydrogen ions were beneficial to the reaction. The temperature also affected the reaction rate and the activation energy of the reaction was 16.6 ± 1.99 kJ·M − 1 . A variety of degradation products were detected and the path of degradation was speculated. Chlorination, dechlorination , and decarboxylation were the main processes of oxidative degradation. Furthermore, the composition of the degradation products was the same at different pH values.
研究领域:
环境科学
·
毒理学
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产品关联
DOI
PubMed
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2023
·
IF 8.6
Wenyu Wang,Ruihua Li,Fan Bu,Yue Gao,Baoyu Gao,Qinyan Yue,Min Yang,Yi Li
The pH conditions affected the binding sites and complexation ability of Al species and humic acid (HA), resulting in the difference of coagulation and membrane fouling mechanism. It is important to explore the dynamic process of coagulation for the mechanisms of Al species and HA. In this study, three Al species (Al a /Al b /Al c ) were used in coagulation process to compare the pollution degree of ultrafiltration (UF). Then, the removal efficiency of Al a for DOC was better than that of Al b and Al c , that is, the removal performance of suspended and dissolved organic matter was better for Al a . Through the analysis of coagulation dynamic process and membrane resistances, the flocs formed were smaller size and grow slowly to the equilibrium stage at pH 4, which was easy to cause membrane fouling by concentration polarization. With the pH increasing to a neutral condition, the flocs had a large size and loose structure, and then the porous cake layer was easy to be removed by physical cleaning, leading to the membrane fouling mainly due to pore plugging. Under alkaline conditions, flocs with small size and dense structure were mainly formed by sweeping, which resulted in the cake layer as the main cause of membrane fouling. This study is helpful to optimize the process of HA removal by coagulation-UF, and provides technical support for the coagulation and membrane mechanism of Al species and HA under different pH conditions.
研究领域:
环境科学
·
水处理工程
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产品关联
DOI
高影响因子
Arabian Journal of Chemistry
·
2020
·
IF 4.762
Hang Yu,Jing Wang,Jun-xia Yu,Yi Wang,Ru-an Chi
Adsorption performance and stability of the carboxyl groups modified straws and their extracts of cellulose, lignin, and hemicellulose for Pb 2+ were investigated, and the optimum pH range for Pb 2+ adsorption was determined by considering both the stability and capacity of the modified biosorbents for the first time. Results showed that adsorption capacity and stability of the straws and extracts were both improved significantly after modification. Adsorption capacities of the modified straws and extracts followed the order: modified hemicellulose > modified lignin, modified straw > modified cellulose, while stability of them followed the reverse order. In the optimum pH range from 4.0 to 5.0, modified rape and cotton straw showed better stability than the modified maize straw, and total organic carbon (TOC) values determined from the two modified straws and extracts were lower than 5.0 mg L −1 even after adsorption for 30 days, which reached the drinking water standard in China.
研究领域:
环境科学
·
生物化学
✓ 已验证
产品关联
DOI
高影响因子
BIORESOURCE TECHNOLOGY
·
2018
·
IF 5.807
Yun Huang,Chaoyang Wei,Qiang Liao,Ao Xia,Xun Zhu,Xianqing Zhu
To improve the carbon to nitrogen (C/N) ratio of harvested microalgae biomass for better producing biogas by fermentation, biodegradable cationic starch with high C/N ratio were synthesized to harvest Chlorella vulgaris . The impact of pH was also studied as the zeta potential of both microalgae and cationic starch would change with pH. Results indicated the cationic starch can harvest above 99% of the microalgae and the C/N ratio can rise from 7.50 to 7.90. The zeta potential of microalgae always kept negative and presented a trend of descending firstly and then upgrade. The maximum microalgae biomass flocculation capacity of 1 g cationic starch was 8.62 g with the help of self-flocculation at pH 3. The concentration of flocs formed at pH 11 was 25.74 g L −1 and the diameter was 0.553 mm which was much larger than the flocs formed at pH 3 (0.208 mm).
研究领域:
生物技术
·
环境科学
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产品关联
DOI
PubMed
高影响因子
BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN
·
2018
·Vol. 91
·期 6
·998-1007
·
IF 3.526
Zhang Xuezhi,Jia Shaoyi,Song Jia,Wu Songhai,Han Xu
Flocculation using Fe(II) instead of Fe(III) has been considered more efficient in the removal of As. However, excess Fe(II) used in the process always leaves substantial TFe [Fe(II)+Fe(III)] unutilized. We therefore developed three methods [the one-staged process (OS), the one-staged process with H2O2 (OSH) and the two-staged process (TS)] to remove As(III)/As(V) by Fe(II) (Fe:As = 2.0). Our results indicate that pH is an important factor that determines the utilization efficiency of TFe and the removal efficiency of As. In OS, the initial pH was adjusted before the reaction. At the optimal pHs of 10.0 and 11.0, the removal efficiencies of As(V) and TAs [As(III)+As(V)] could reach 84.0% and 66.7%, with only 61.9% and 80.2% TFe being utilized, respectively. In OSH, H2O2 was added after pH adjustment. After OS, pH was re-adjusted to the optimal values before the next 30 min reaction (TS). Compared with OS, the removal efficiencies of As could increase by more than 9% in OSH and TS at the optimal pHs. Besides, there is more than 10% improvement in the utilization efficiencies of TFe except at 12.0. Accelerating oxidation of Fe(II) or re-adjusting pH is therefore highly efficient for a more efficient removal of As from Fe(II)-rich groundwater.
研究领域:
环境科学
·
水处理工程
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DOI
高影响因子
JOURNAL OF SOL-GEL SCIENCE AND TECHNOLOGY
·
2014
·Vol. 71
·期 3
·597-605
·
IF 1.547
Zhang Hui,Zhan Kan,Chen Yulu,Chen Guoxia,Zhou Xiaomei,Liu Junxiu,Wu Min,Ni Henmei
Three dimensional Liesegang spherical layers of CaHPO 4 in gelatin ball were performed by employing CaCl 2 and Na 2 HPO 4 as the inner and outer electrolyte, respectively. Effects of concentrations of inner and outer electrolyte as well as pH on the morphologies of Liesegang rings (LRs) were investigated. As a result, it was observed that the time law, spacing law and width law found in 1D/2D gel systems were obeyed in this 3D gelatin system. The interaction of Ca 2+ and HPO 4
2− with gelatin matrix played a key role to the formation of LRs due to the existence of carboxylic groups on the gelatin chains. Using Ca 2+ as the inner electrolyte, LRs were prepared. However, employing HPO 4
2− as inner electrolyte, LRs were not obtained. Moreover, pH of gelatin solution greatly impacted on the formation of LRs. The number of LRs increased with the decrease of pH, whereas the width inversely decreased. pH 4.40 was a turn point, from which the spacing coefficient abruptly increased as pH increased. All these results indicated that the network was created by the interaction of Ca 2+ and –COO − of gelatin chains, which dominated the formation of CaHPO 4 LRs in gelatin.
研究领域:
生物材料学
·
物理化学
·
软物质物理
·
胶体科学
·
生物矿化
✓ 已验证
DOI
高影响因子
INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
·
2022
·
IF 8.025
Bin Zhou,Mengchen Li,Jingyun Zhao,Yujuan Rong,Hongshan Liang,Bin Li
Heat-induced gel-assisted desalination could efficiently and inexpensively remove salt from salted egg whites . However, it was at the expense of the excellent foaming properties of egg whites, caused by the denaturation and aggregation of proteins during heating treatment. Hence, in this current work, the enzymatic treatment was used to re-endow duck egg white nanogels (DEWN) with outstanding foaming properties. We found that low levels of hydrolysis (DH = 2.27 %) could dramatically improve the foaming capability (FC), reaching >200 %, which also enhanced the foaming stability (FS). As the hydrolysis time extended, the adsorption and diffusion rate of the supernatant on the interface increased and performed high elasticity. The dilatational rheology and Lissajous plots were explored to investigate the nonlinear dilatational rheological behaviors of the air/water interface stabilized by the hydrolysed samples. Finally, we evaluated the effect of pH on foaming properties and found that the FC could exceed 250 %, and the FS was close to 80 % at pH = 5. These encouraging results showed that simple enzymatic treatment could revive nanogels from their dissatisfied foaming properties. In this work, gel-assisted desalination combined with enzyme treatment significantly promotes the high-quality and high-value utilization of salted egg white.
研究领域:
食品科学
·
蛋白质化学
✓ 已验证
DOI
高影响因子
SCIENCE OF THE TOTAL ENVIRONMENT
·
2018
·
IF 4.61
Shuran He,Yongtao Li,Liping Weng,Jinjin Wang,Jinxian He,Yonglin Liu,Kun Zhang,Qihong Wu,Yulong Zhang,Zhen Zhang
In present study, the feasibility of applying a natural adsorbent with Fe 3+ modification (Fe 3+ -modified argillaceous limestone, FAL) on the competitive adsorption of heavy metals (i.e., Cd 2+ , Pb 2+ and Ni 2+ ) was evaluated. The current results revealed an efficient adsorption on Cd 2+ , Pb 2+ and Ni 2+ in mono-metal system. Further experiments demonstrated a high selectivity of Pb 2+ during the competitive adsorption of Cd 2+ , Pb 2+ and Ni 2+ . The adsorption selectivity of the metal ions followed the order of Pb ≫ Cd > Ni. In addition, both pH and ionic strength are important factors affecting the metal adsorptions. It is interestingly that various NOMs (i.e., humic acid (HA) and glycine (Gly)) exerted different effects on the adsorption behaviors, probably due to the different affinities for Pb 2+ , Cd 2+ and Ni 2+ and the redistribution of newly-formed metal-DOM complexes. X-ray photoelectron spectroscopy (XPS) analysis together with X-ray diffraction (XRD) and energy dispersive spectrometer (EDS) analysis revealed that the metal adsorptions were mainly regulated via the synergistic mechanisms of ion exchange by Na + , Ca 2+ , and Al 3+ , precipitation to form CdCO 3 and Pb 2 (OH) 2 (CO 3 ) 2 , as well as complexes of FAL-OPb and FAL-ONi by hydroxyl groups on the surface of FAL. The application of FAL would be a promising option in leading to an efficient heavy metal removal.
研究领域:
环境科学
·
化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
危险品化学品经营许可证（带存储）