Effect of phosphate on heterogeneous Fenton oxidation of catechol by nano-Fe3O4: Inhibitor or stabilizer?

The effect of phosphate on adsorption and oxidation of catechol, 1,2-dihydroxybenzene, in a heterogeneous Fenton system was investigated. In situ attenuated total reflectance infrared spectroscopy (ATR-FTIR) was used to monitor the surface speciation at the nano-Fe₃O₄ catalyst surface. The presence of phosphate decreased the removal rate of catechol and the abatement of dissolved organic compounds, as well as the decomposition of H₂O₂. This effect of phosphate was mainly due to its strong reaction with surface sites on the iron oxide catalyst. At neutral and acid pH, phosphate could displace the adsorbed catechol from the surface of catalyst and also could compete for surface sites with H₂O₂. In situ IR spectra indicated the formation of iron phosphate precipitation at the catalyst surface. The iron phosphate surface species may affect the amount of iron atoms taking part in the catalytic decomposition of H₂O₂ and formation of hydroxyl radicals, and inhibit the catalytic ability of Fe₃O₄ catalyst. Therefore, phosphate ions worked as stabilizer and inhibitor in a heterogeneous Fenton reaction at the same time, in effect leading to an increase in oxidation efficiency in this study. However, before use of phosphate as pH buffer or H₂O₂ stabilizer in a heterogeneous Fenton system, the possible inhibitory effect of phosphate on the actual removal of organic pollutants should be fully considered.     

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.     

1981—2010年内蒙古草地土壤有机碳时空变化及其气候敏感性

草地土壤有机碳储量巨大,其较小幅度的波动即可能显著反馈于气候变化. 基于1981—2010年内蒙古自治区境内及其周边共计92个气象台站气候要素插值数据,采用空间化的生物地球化学模型——CENTURY 4.5,模拟分析近30年来内蒙古草地表层(0~20 cm)土壤有机碳的空间格局与动态变化特征,并通过构建气候变化情景探讨其对主要气候要素的敏感性. 结果表明:近30年内蒙古草地表层土壤有机碳密度平均值约为1.99 kg/m2(以C计),在空间上呈由东北向西南逐渐减少的分布特征. 近30年来内蒙古草地表层土壤有机碳密度略有增加,年均增幅约0.22%,其中草甸草原的增速〔14.25 g/(m2·a)〕最大,荒漠草原的增速〔1.36 g/(m2·a)〕最小. 草地表层土壤有机碳密度年际变化差异明显,1980s至1990s的增加较为缓慢,1990s至2000s的增幅约为前者的2倍,其中草甸草原和典型草原土壤有机碳增幅较大. 气候敏感性分析结果显示,区域降水量变化可能是近30年内蒙古草地表层土壤有机碳密度变化的主要影响因素,但不同草地类型表层土壤有机碳密度对气候变化的敏感性存在较大差异;典型草原与草甸草原表层土壤有机碳变化主要受控于降水量变化,荒漠草原则主要受控于温度变化.      

我国农用地土壤环境基准与标准制定研究

在分析我国现行土壤环境质量标准不足的基础上,综述了国外制定农用地土壤环境筛选值的现状,在此基础上提出我国农用地土壤环境基准制定方法学的建议以及我国农用地土壤环境标准体系的框架建议,服务于我国农用地土壤的污染预防、风险筛选和污染农用地的安全利用、修复和风险管控。     

Deposition behavior of residual aluminum in drinking water distribution system: Effect of aluminum speciation

Finished drinking water usually contains some residual aluminum.The deposition of residual aluminum in distribution systems and potential release back to the drinking water could significantly influence the water quality at consumer taps.A preliminary analysis of aluminum content in cast iron pipe corrosion scales and loose deposits demonstrated that aluminum deposition on distribution pipe surfaces could be excessive for water treated by aluminum coagulants including polyaluminum chloride（PACl）.In this work,the deposition features of different aluminum species in PACl were investigated by simulated coil-pipe test,batch reactor test and quartz crystal microbalance with dissipation monitoring.The deposition amount of non-polymeric aluminum species was the least,and its deposition layer was soft and hydrated,which indicated the possible formation of amorphous Al（OH）₃.Al₁₃ had the highest deposition tendency,and the deposition layer was rigid and much less hydrated,which indicated that the deposited aluminum might possess regular structure and self-aggregation of Al₁₃could be the main deposition mechanism.While for Al₃₀,its deposition was relatively slower and deposited aluminum amount was relatively less compared with Al₁₃.However,the total deposited mass of Al₃₀ was much higher than that of Al₁₃,which was attributed to the deposition of particulate aluminum matters with much higher hydration state.Compared with stationary condition,stirring could significantly enhance the deposition process,while the effect of pH on deposition was relatively weak in the near neutral range of 6.7 to 8.7.     

区域大气环境容量及其区域配置研究

以重庆市涪陵区为例,在了解区域大气环境功能区划及区域大气环境质量现状的前提下,采用A-P值法,对涪陵区十三五期间大气环境容量进行研究,并对辖区内的污染负荷进行预测,在此基础上,对大气污染总量控制指标进行分配.研究结果表明,在涪陵区化工园区的二氧化硫排放量已达到或超过总量控制指标,需要制定削减计划,新兴工业园区污染物排放量虽远小于总量控制指标,但根据城市发展规划需进行结构优化与合理布局.     

电渗析技术在浓盐水回收项目的应用研究

电渗析技术作为一种新兴的膜分离技术,因高效率低能耗、对预处理要求低、对分离组分选择性高、原水回收率高、环境友好等优点,在国内外各行业获得广泛应用.江苏华晖环保科技有限公司改进了电渗析工艺参数,并在贵州开磷(集团)有限责任公司进行了推广应用,大大降低了出水中Cl-和Ca2+浓度,电导率由数千us/cm降到200 us/cm以下.电渗析技术可节约水资源,社会、环境、经济效益显著,对企业实现真正的“零排放”具有巨大的推动力.     

地理数据库的构建及其在水利工程环境影响评价中的应用研究

GIS技术为环境影响评价提供了高效的操作平台和有力的技术支撑,应用GIS技术建立的地理数据库,有助于科学地分析、预测和评估工程实施对周边环境可能造成的影响.文章简述了地理数据库的模块结构及构建流程,并结合贵州省夹岩水利枢纽及黔西北供水工程环境影响评价工作对地理数据库在图件制作、环境敏感目标识别、水文信息提取与分析、生态影响评价等方面的应用进行了介绍.最后指出GIS技术相对于传统评价技术的优点,并对其应用前景进行了展望.     

Lead (Pb) exposure and heart failure risk

Environmental Science and Pollution Research - Lead (Pb) is a heavy metal with widespread industrial use, but it is also a widespread environmental contaminant with serious toxicological...