An antifouling catechol/chitosan-modified polyvinylidene fluoride membrane for sustainable oil-in-water emulsions separation

• Underwater superoleophobic membrane was fabricated by deposition of catechol/chitosan. • The membrane had ultrahigh pure water flux and was stable under harsh pH conditions. • The membrane exhibited remarkable antifouling property in O/W emulsion separation. • The hydration layer on the membrane surface prevented oil droplets adhesion. Low-pressure membrane filtrations are considered as effective technologies for sustainable oil/water separation. However, conventional membranes usually suffer from severe pore clogging and surface fouling, and thus, novel membranes with superior wettability and antifouling features are urgently required. Herein, we report a facile green approach for the development of an underwater superoleophobic microfiltration membrane via one-step oxidant-induced ultrafast co-deposition of naturally available catechol/chitosan on a porous polyvinylidene fluoride (PVDF) substrate. Membrane morphology and surface chemistry were studied using a series of characterization techniques. The as-prepared membrane retained the original pore structure due to the ultrathin and uniform catechol/chitosan coating. It exhibited ultrahigh pure water permeability and robust chemical stability under harsh pH conditions. Moreover, the catechol/chitosan hydrophilic coating on the membrane surface acting as an energetic barrier for oil droplets could minimize oil adhesion on the surface, which endowed the membrane with remarkable antifouling property and reusability in a cyclic oil-in-water (O/W) emulsion separation. The modified membrane exhibited a competitive flux of ~428 L/(m²·h·bar) after three filtration cycles, which was 70% higher than that of the pristine PVDF membrane. These results suggest that the novel underwater superoleophobic membrane can potentially be used for sustainable O/W emulsions separation, and the proposed green facile modification approach can also be applied to other water-remediation materials considering its low cost and simplicity.     

螯合剂对小麦幼苗吸收金属以及土壤金属形态的效应

本文通过盆栽试验研究三种螯合剂（EDTA、[s,s】-EDDS、DTPA）对小麦幼苗吸收土壤中重金属及其它微量元素的效应,并且通过改进的BCR连续提取法分析了种植后土壤样品中金属元素的形态。结果表明：EDTA、DTPA的添加导致小麦幼苗地上部分生物量以及叶片叶绿素a含量显著下降。螯合剂的存在明显增加了Pb和Mn在幼苗根部和茎叶的富集,并增加其由根部向茎叶的传输．但对Fe和Ni的作用比较小。小麦幼苗收获时,除Zn之外,其它元素酸溶／可交换态金属含量与对照组相比均有非常显著的增加,而各元素的可还原态由于EDTA等螯合剂的添加而有明显下降。添加螯合剂的情况下,富集量与酸溶／可交换态含量之间的相关系数大大提高,且各处理组茎叶富集量与酸溶／可交换态之间呈显著（P〈0．05）或极显著相关（P〈0．01）。因此,三种螯合剂的添加主要影响的是生物可利用形态以及潜在的生物可利用形态,并且可能导致可还原态以及可氧化态向酸溶／可交换态转变,增加金属的生物可利用性,从而也增加潜在生态风险。     

聚氨酯型固沙剂改性土室内试验研究

对自主研发的PUA、PUB和PUC 3种聚氨酯型固沙剂改性土的强度、抗冲刷性、抗风蚀性等性能进行了室内试验研究,并结合聚氨酯分子结构和功能对固沙剂改良原理进行了分析。试验结果表明:3种聚氨酯型固沙剂改性土的无侧限抗压强度、内聚力得到了提高,抗冲刷和抗风蚀性能得到了明显增强;3种固沙剂改性土的无侧限抗压强度和内聚力均随着固沙剂浓度的增加而增大;PUA、PUB和PUC浓度为3g/cm3的改性土试样的冲刷率分别只有4.4%、14.7%和0.6%,而参照样高达79.5%;PUA、PUB和PUC浓度达到1g/cm3以上的改性土风蚀后表面保持完整,没有风蚀破坏痕迹。因此,聚氨酯型固沙剂可以很好地增强土体粘聚力、促进表层固化、减少水土流失,可用于坡面防护、水土保持、防尘固沙、沙漠化治理等领域。     

螯合剂对铜毒性的影响

研究了螯合剂EDTA和DTPA对海州香薷蓄铜能力和铜毒性的影响.结果显示,EDTA和DTPA能抑制植物的生长,使其生物量降低,叶绿素含量下降,同时降低了植物的根系活力.EDTA和DTPA都可引起植物SOD、POD活性上升,在与Cu²⁺共同作用下,EDTA对Cu²⁺毒性影响较小,表现在SOD、POD活性仍按Cu²⁺独立作用下的变化规律而变化,且数值上变化不大.而DTPA则降低了Cu²⁺作用下SOD、POD活性的变化.EDTA使海州香薷地上部分铜浓度增加,DTPA则明显降低了海州香薷的铜含量.     

取代脲类除草剂光催化降解动力学比较

为研究取代脲类除草剂在TiO₂光催化降解过程中的动力学规律,以非草隆、异丙隆和利谷隆3种取代脲类除草剂为研究对象,通过Langmuir-Hinshelwood动力学模型对其TiO₂光催化降解动力学进行模拟,并系统探讨了催化剂用量、C₀(取代脲类除草剂的初始浓度)、溶液pH、温度、ROSs(活性氧物种)和电子捕获剂等的影响. 结果表明:非草隆、异丙隆和利谷隆的TiO₂光催化降解均符合假一级动力学模型,其动力学常数分别为0.082 8、0.068 7和0.095 4 min-1;取代脲类除草剂分子中的芳香环和脲桥上的取代基对降解速率常数的大小有明显的影响. ROSs试验表明,非草隆、异丙隆和利谷隆光催化降解过程中分别有91.6%、95.5%和86.8%的贡献来自·OH;而光生空穴和其他ROSs的贡献相对较小,并且电子捕获剂BrO₃-和S₂O₈2-对取代脲类除草剂的降解动力学有显著的促进作用.      

Ozonation of the 5-fluorouracil anticancer drug and its prodrug capecitabine: Reaction kinetics,oxidation mechanisms,and residual toxicity

Specific second-order rate constants were determined for 5-FU and CAP with ozone. Reaction sites were confirmed by kinetics, Fukui analysis, and products. The olefin moiety was the main ozone reaction site for 5-FU and CAP. Carboxylic acids comprised most of the residual TOC for 5-FU. Ozonation removed the toxicity associated with 5-FU and products but not CAP. Anticancer drugs (ADs) have been detected in the environment and represent a risk to aquatic organisms, necessitating AD removal in drinking water and wastewater treatment. In this study, ozonation of the most commonly used antimetabolite ADs, namely 5-fluorouracil (5-FU) and its prodrug capecitabine (CAP), was investigated to determine reaction kinetics, oxidation mechanisms, and residual toxicity. The specific second-order rate constants between aqueous ozone and 5-FU, 5-FU⁻, 5-FU²⁻, CAP, and CAP⁻ were determined to be 7.07(±0.11)×10⁴ M⁻¹·s⁻¹, 1.36(±0.06)×10⁶ M⁻¹·s⁻¹, 2.62(±0.17)×10⁷ M⁻¹·s⁻¹, 9.69(±0.08)×10³ M⁻¹·s⁻¹, and 4.28(±0.07)×10⁵ M⁻¹·s⁻¹, respectively; furthermore, the second-order rate constants for ^•OH reaction with 5-FU and CAP at pH 7 were determined to be 1.85(±0.20)×10⁹ M⁻¹·s⁻¹ and 9.95(±0.26)×10⁹ M⁻¹·s⁻¹, respectively. Density functional theory was used to predict the main ozone reaction sites of 5-FU (olefin) and CAP (olefin and deprotonated secondary amine), and these mechanisms were supported by the identified transformation products. Carboxylic acids constituted a majority of the residual organic matter for 5-FU ozonation; however, carboxylic acids and aldehydes were important components of the residual organic matter generated by CAP. Ozone removed the toxicity of 5-FU to Vibrio fischeri, but the residual toxicity of ozonated CAP solutions exhibited an initial increase before subsequent removal. Ultimately, these results suggest that ozone is a suitable technology for treatment of 5-FU and CAP, although the residual toxicity of transformation products must be carefully considered.     

Antifouling paints: Use on boats in San Diego Bay and a way to minimize adverse impacts

High concentrations of copper and tributyltin, two biocides used in antifouling paints, are found in harbors. Efforts are necessary to reduce the adverse impact of biocides from antifouling paints, but little is known about the actual use of such material. I surveyed the operators of 435 boats berthed in San Diego Bay, to determine what paints and maintenance procedures were being used.More than 90% of the respondents used conventional leaching paints. These paints contain 40% to 65% copper compounds and 3% to 7% tributyltin compounds. Few respondents used copolymer paints. Those who did use copolymer paints seemed to repaint less frequently than those using conventional leaching paints.Professional maintenance companies do not initiate repainting as frequently as individuals doing their own maintenance.It appears that the input of antifouling biocides to harbor waters could be reduced by at least one-third simply by educating boat-owners about the chemical mechanisms involved in antifouling paints, by explaining the environmental and economic advantages of using slow-release paints, and by encouraging them not to repaint until their paint's useful life has expired.     

高浓度豆制品废水预处理实验研究

豆制品是中国的传统食品,在生产过程中产生高浓度废水,如果对高浓度有机废水进行预处理,采用回收蛋白质以及化学混凝处理方法可以大大降低废水浓度,一定程度上可以减轻后续处理的难度、降低处理成本。针对豆制品生产废水问题,对高浓度豆制品废水的预处理方法作了实验研究。采用调节等电点酸沉降的方法回收蛋白质,然后用聚合硫酸铁化学混凝处理上清液以降低COD的含量。实验证明了方法的可行性并得出了最佳实验条件。     

Oxidation of diesel soot on binary oxide CuCr(Co)-based monoliths

Binary oxide systems (CuCr₂O₄, CuCo₂O₄), deposited onto cordierite monoliths of honeycomb structure with a second support (finely dispersed Al₂O₃), were prepared as filters for catalytic combustion of diesel soot using internal combustion engine's gas exhausts (O₂, NO_x, H₂O, CO₂) and O³ as oxidizing agents. It is shown that the second support increases soot capacity of aforementioned filters, and causes dispersion of the particles of spinel phases as active components enhancing thereby catalyst activity and selectivity of soot combustion to CO₂. Oxidants used can be arranged with reference to decreasing their activity in a following series: O₃ >> NO₂ > H₂O > NO > O₂ > CO₂. Ozone proved to be the most efficient oxidizing agent: the diesel soot combustion by O₃ occurs intensively (in the presence of copper chromite based catalyst) even at closing to ambient temperatures. Results obtained give a basis for the conclusion that using a catalytic coating on soot filters in the form of aforementioned binary oxide systems and ozone as the initiator of the oxidation processes is a promising approach in solving the problem of comprehensive purification of automotive exhaust gases at relatively low temperatures, known as the "cold start" problem.     

Determination of chemical warfare agents

Ethylarsine dichloride was used during WW I as a chemical warfare agent. Residues of this chemical warfare agent and its metabolites are still present today and continue to contaminate soil and water. A gas Chromatographic method for the detection and determination of ethylarsine dichloride is shown. Six dithiols were tested as possible derivatization reagents for ethylarsine dichloride. With selection of the dithiol, matrix interferences can be eliminated because of the different retention times of the derivatives.