Adsorptive removal of As(III) and As(V) from water and wastewaters using an anion exchanger derived from polymer-grafted banana stem

In this study, the adsorption characteristics of As(III) and As(V) from water and wastewater using polyacrylamide-grafted banana stem with quaternary ammonium functionality (PGBS-AE) were investigated. Infrared spectroscopic, and thermogravimetric analyses were performed to affirm the polymer grafting, functionality, morphology, and thermal stability. Batch experiments were carried out to understand the effect of contact time, concentration, pH, adsorbent dose, and temperature of the solution for the adsorption of As(III) and As(V) onto PGBS-AE. Equilibrium was achieved within 1 h and the optimum pH was found to be 9.0 and 3.0 for As(III) and As(V), respectively. Isotherm studies showed that the Langmuir equation fits best. Maximum adsorption capacities of 50 and 5.5?g?kg^?1 were obtained for As(III) and As(V) at 30°C. The endothermic nature of adsorption was evident as the adsorption efficiency increased with temperature. The thermodynamic parameters were evaluated to explain the feasibility of adsorption and to predict the nature of adsorption. The competence of the adsorbent for practical purposes was also analyzed by treating with a fertilizer industry effluent sample. Studies pertaining to adsorbent regeneration and readsorption of As(III) and As(V) were carried out for four consecutive cycles.     

丙烯燃爆危险性分析

为预防丙烯氧化制环氧丙烷工艺流程中丙烯燃爆危险的发生,利用5 L爆炸极限测试仪测定丙烯在空气中常压不同温度条件下的爆炸极限,得到丙烯在常压下爆炸极限随温度的变化情况;针对丙烯工艺中的典型工况,采用11 L爆轰管测定不同工况温度、压力条件下,丙烯在空气中不同氧含量下的爆炸极限,并以此绘制爆炸极限三元图,得到不同工况条件下"丙烯-氧气-氮气"混合体系的燃爆区域。结果表明:随着温度、压力及氧气含量的升高,丙烯爆炸上限明显提高,但爆炸下限变化不明显;丙烯在80℃、0.24 MPa,130℃、0.96 MPa,40℃、1.90 MPa条件下的极限氧含量(LOC)分别为11.0%,10.2%和10.8%。降低体系中氧气含量有助于预防丙烯燃爆危险的发生。     

运用相图理论回收缩合废水中的氯化钠和氯化铵

研究了0℃,10℃,60℃时NaCl－NH4 Cl－H2 O三元水盐体系的固液相平衡关系,测出了NaCl和NH4 Cl在水中的溶解度数据,并绘制了相图。运用该三元相图理论,采用结晶法从缩合工段母液废水中回收NaCl和NH4 Cl。讨论了回收过程原理,介绍了回收工艺的操作步骤和工艺参数。回收的NaCl纯度达到95％,总回收率大于77％,NH4 Cl纯度达到92％以上,总回收率大于40％,产品分别达到HG／T 5462—2003,GB／T 2946—2008的标准。     

Graft Copolymers, for Erodible Resins, from α-Hydroxyacids Oligomers Macromonomers and Acrylic Monomers

Environmental concerns result in a progressive withdrawal of antifouling paints containing organotin derivatives. The nature of the binders is critical with regard to the erosion of the protecting film through factors such as bond cleavage, dissolution, and diffusion of the degradation products. The versatility of acrylic polymers, due to the possibility of varying their chemical structure had conducted, in the first stage, to combine different types of repeating units in the macromolecular backbone. Formulation and evaluation, in natural sites, of these binders, with a well-defined hydrophobic/hydrophilic balance and with hydrolyzable pendant groups, have shown the possibility to prepare new organotin free resins which can be formulated and which are erodible in seawater over a long period (more than 2 years). A further step has been engaged with the development of graft copolymers containing biocompatible and hydrolyzable oligomers of -hydroxyacids. Their preparation requires the synthesis of -methacryloyloxyoligo--hydroxyacid macromonomers. Copolymers prepared from a mixture of the macromonomer and of an alkyl ester of acrylic acid were formulated with a biocide and deposited on a plate. Their ability to release cuprous oxide, as a model molecule, has been checked and quantified by the inductively coupled plasma analytical method. The uptake of water in the paint, which is enhanced by the hydrolysis of -hydroxyacid oligomers, as determined by the enzymatic measurement of liberated L-lactic acid, conducts to the polymer erosion and to a protecting bioactive surface.     

Starch-plastic materials—Preparation,physical properties,and biodegradability (a review of recent USDA research)

Recent starch-plastic research at the National Center for Agricultural Utilization Research is reviewed and related worldwide efforts are noted. Properties of starch that influence its formulation and performance in plastics are discussed. Methods are given for preparation of starch-poly(methyl acrylate) graft copolymer, starch-poly(ethylene-co-acrylic acid), and starch-poly(ethylene-co-acrylic acid)-polyethylene plastics. Their physical properties are discussed, as is degradability by enzymes or amylolytic organisms from soil, ponds, and streams.The mention of firm names or trade products does not imply that they are endorsed or recommended by the U.S. Department of Agriculture over other firms or similar products not mentioned.     

改性玉米秸秆材料的制备及吸油性能的研究

以粉末状玉米秸秆(Raw corn stalks,RCS)为基体,甲基丙烯酸丁酯和苯乙烯为单体,采用悬浮聚合法制备高吸油复合材料(Butylmethacrylate and styrene grafted corn stalks,BMS-CS).实验确定的最佳制备条件为:在50℃,引发剂硝酸铈铵为2.0mmol·L-1,单体甲基丙烯酸丁酯和苯乙烯浓度分别为0.6mol·L-1、0.012mol·L-1,交联剂N,N’-亚甲基双丙烯酰胺质量分数为0.1%(相对于RCS的质量)的前提下反应25h.同时,实验考察了吸附时间、吸附温度及保油时间等对材料吸油性能的影响,并通过傅里叶变换红外光谱仪、X-射线衍射和扫描电镜对改性前后样品的结构进行表征.结果表明,BMS-CS表面变得粗糙且呈毛刺状,具有较多不规则的褶皱;结晶度的下降也印证了粗糙度的增加;红外图谱中新出现的酯基和苯乙烯基的吸收峰说明亲油单体被接枝到RCS表面;两种原因共同促进了改性材料吸油性能的增加.吸油数据显示,常温下RCS和BMS-CS的吸油量分别为5.23g·g-1和20.12g·g-1,后者是前者的3.85倍,即改性后的材料吸油性能明显增加.     

壳聚糖接枝共聚物的合成及应用研究

在N2保护下,以浓度为0.8 mmol/L硝酸铈铵为引发剂,控制壳聚糖(CTS)和丙烯酰胺(AM)质量比为mCTS∶mAM=1∶6,于50℃下接枝共聚反应3 h,得改性的壳聚糖衍生物(CAM).用IR对产物进行表征.通过对废水的处理,研究了共聚产物在絮凝、COD去除、脱色上的应用.结果表明:CAM的絮凝效果好于聚丙烯酰胺和壳聚糖,CAM对COD的去除率达到84.7%,并有较好的脱色效果.     

聚季铵盐丙烯酰胺接枝共聚物治理煤泥水的应用研究

本文研究了聚季铵盐丙烯酰胺接枝共聚物PQAAM在煤泥水治理中的絮凝沉降作用,说明该絮凝剂是一种质量优良的新型高效的阳离子絮凝剂,对煤泥水治理和环境保护有着广泛的应用前景。     

Modifying glass fiber surface with grafting acrylamide by UV-grafting copolymerization for preparation of glass fiber reinforced PVDF composite membrane

Experimental design and response surface methodology(RSM) were used to optimize the modification of conditions for glass surface grafting with acrylamide(AM) monomer for preparation of a glass fiber reinforced poly(vinylidene fluoride)(PVDF) composite membrane(GFRP-CM). The factors considered for experimental design were the UV(ultraviolet)-irradiation time, the concentrations of the initiator and solvent, and the kinds and concentrations of the silane coupling agent. The optimum operating conditions determined were UV-irradiation time of 25 min, an initiator concentration of 0–0.25 wt.%,solvent of N-Dimethylacetamide(DMAC), and silane coupling agent KH570 with a concentration of 7 wt.%. The obtained optimal parameters were located in the valid region and the experimental confirmation tests conducted showed good accordance between predicted and experimental values. Under these optimal conditions, the water absorption of the grafted modified glass fiber was improved from 13.6% to 23%; the tensile strength was enhanced and the peeling strength of the glass fiber reinforced PVDF composite membrane was improved by 23.7% and 32.6% with an AM concentration at 1 wt.% and 2 wt.%. The surface composition and microstructure of AM grafted glass fiber were studied via several techniques including Field Emission Scanning Electron Microscopy(FESEM), Fourier transform infrared spectroscopy-attenuated total reflectance(FTIR-ATR) and energy dispersive X-ray spectroscopy(EDX). The analysis of the EDX and FTIR-ATR results confirmed that the AM was grafted to the glass fiber successfully by detecting and proving the existence of nitrogen atoms in the GFRP-CM.     

生态系统服务的三元价值理论及在大尺度生态补偿上的应用探讨

传统的生态系统服务价值评估方法在生态补偿具体实践中仍存在一些困境。本研究提出生态系统服务功能的三元价值理论,通过能值方法剥离纯自然贡献带来的服务价值、自然贡献和人类投入共同作用形成的服务价值及基于人类偏好的存在价值这三类价值,通过自然贡献可以确定生态补偿的理论基线,而人工投入(基于人类投入绩效的支付)和存在价值(基于偏好的支付)可对基线进行二级修正,进一步提出了利用三元价值理论系统解决"生态系统服务—受益区—补偿方式—补偿标准—受偿主体"问题的生态补偿路径。