Kinetic and mechanism studies of the adsorption of lead onto waste cow bone powder (WCBP) surfaces

This study examines the adsorption isotherms, kinetics and mechanisms of Pb2(+) sorption onto waste cow bone powder (WCBP) surfaces. The concentrations of Pb2(+) in the study range from 10 to 90 mg/L. Although the sorption data follow the Langmuir and Freundlich isotherm, a detailed examination reveals that surface sorption or complexation and co-precipitation are the most important mechanisms, along with possibly ion exchange and solid diffusion also contributing to the overall sorption process. The co-precipitation of Pb2(+) with the calcium hydroxyapatite (Ca-HAP) is implied by significant changes in Ca2(+) and PO?3? concentrations during the metal sorption processes. The Pb2(+) sorption onto the WCBP surface by metal complexation with surface functional groups such as ≡ POH. The major metal surface species are likely to be ≡ POPb(+). The sorption isotherm results indicated that Pb2(+) sorption onto the Langmuir and Freundlich constant q(max) and K( F ) is 9.52 and 8.18 mg g?1, respectively. Sorption kinetics results indicated that Pb2(+) sorption onto WCBP was pseudo-second-order rate constants K? was 1.12 g mg?1 h?1. The main mechanism is adsorption or surface complexation (≡POPb(+): 61.6%), co-precipitation or ion exchange [Ca?(.)?? Pb?(.)?? (PO?)? (OH): 21.4%] and other precipitation [Pb 50 mg L?1 and natural pH: 17%). Sorption isotherms showed that WCBP has a much higher Pb2(+) removal rate in an aqueous solution; the greater capability of WCBP to remove aqueous Pb2(+) indicates its potential as another promising way to remediate Pb2(+)-contaminated media.     

Potential application of sludge produced from coal mine drainage treatment for removing Zn(II) in an aqueous phase

Various analyses of physico-chemical characteristics and batch tests were conducted with the sludge obtained from a full-scale electrolysis facility for treating coal mine drainage in order to find the applicability of sludge as a material for removing Zn(II) in an aqueous phase. The physico-chemical analysis results indicated that coal mine drainage sludge (CMDS) had a high specific surface area and also satisfied the standard of toxicity characteristic leaching procedure (TCLP) because the extracted concentrations of certain toxic elements such as Pb, Cu, As, Hg, Zn, and Ni were much less than their regulatory limits. The results of X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) showed that the CMDS mainly consists of goethite (70%) and calcite (30%) as a weight basis. However, the zeta potential analysis represented that the CMDS had a lower isoelectric point of pH (pH(IEP)) than that of goethite or calcite. This might have been caused by the complexation of negatively charged anions, especially sulfate, which usually exists with a high concentration in coal mine drainage. The results of Fourier transform infrared (FT-IR) spectrometry analysis revealed that Zn(II) was dominantly removed as a form of precipitation by calcite, such as smithsonite [ZnCO?] or hydrozincite [Zn?(CO?)?(OH)?]. Recycling sludge, originally a waste material, for the removal process of Zn(II), as well as other heavy metals, could be beneficial due to its high and speedy removal capability and low economic costs.     

沼液培养的普通小球藻对CO2的去除

利用微藻固定CO2和处理污水已成为微藻应用的一个重要研究方向.利用营养丰富的沼气发酵废液培养小球藻,藻种经驯化后在不同浓度沼液中能良好生长.小球藻在高浓度的CO2中有较好的生长和较强的耐受能力,在1.5%CO2通气下生物量最高.在此基础上考察了沼液中小球藻对CO2的去除情况.结果表明,提高小球藻生长速率和CO2浓度可以增加小球藻对CO2的去除量,降低通气也可提高CO2去除率.在1.5%CO2浓度、通气量60 mL min-1条件下,CO2去除率可达30.61%;在10%CO2浓度、通气量100 mL min-1时最高去除量为279.7 mg L-1 h-1.采用六管串联通气培养小球藻去除粗沼气中的CO2,去除量为(205.80±13.20)mg L-1 h-1,去除率为60.32%±3.73%.在同样的通气量下,CO2的去除量与单管培养相近,去除率是单管培养的近6倍,因此小球藻对沼气中的CO2具有良好的去除效果.图4表2参17     

纳米ZnO与TiO2对赤子爱胜蚓(Eisenia foetida)的毒性效应

以赤子爱胜蚓(Eisenia foetida)为受试生物,研究纳米TiO2与ZnO两种纳米颗粒的毒理学效应及环境释放风险.实验采用滤纸法(浓度组:0、0.15、0.75、1.5和3.0 mg·cm-2)和溶液法(浓度组:0、10、50和100 mg·L-1),染毒时间为48 h,以抗氧化系统的响应和DNA损伤作为毒理效...     

强降雨在滑坡发育中的关键控制机理及典型实例分析

通过构建水动力作用模型,对降雨的激发控制作用进行分析,得出水动力控制机理的结论:强降雨控制滑坡发育,集中表现在改变土体的静水压力、动水压力与浮托力的作用三方面.选取重庆市黔江流水湾滑坡为典型实例,对强降雨的激发控制作用进行验证,强降雨的水动力作用过程分为坡体剪切、滑动开始、剧烈滑动三个不同阶段.最后,提出久旱过后强降雨...     

环境科技创新在绿色经济发展中的应用与实践研究

在雾霾天气越来越严重、环境污染日益恶化的背景下,环境的污染问题明显突出,也成为经济发展的一大障碍。为此,绿色经济发展得到更多人的认识和赞同。人们在发展经济的同时,重视绿色经济的发展,同时更重视环境科技创新在绿色经济发展中的应用。绿色文明是追求人类和自然界的和谐统一,环境保护与经济发展的协调发展。它需要对绿色资源的可持续利用,资源利用不能超过替代资源的发展速度;污染排放量不能超过自净系统的自然规律,科学合理地利用资源。科技创新、绿色文明符合中国当前可持续发展的总体要求,是发展绿色循环经济的思想基础。     

南宁市HJ-1CCD数据气溶胶光学厚度反演

利用环境一号卫星(HJ-1)CCD数据高时间分辨率、空间分辨率和宽覆盖的特点,进行城市地区气溶胶光学厚度定量反演研究。提出使用环境卫星数据自带的逐像元卫星观测角度文件及相应参数进行逐像元太阳天顶角、太阳方位角推算,生成四波段合成角度数据。结合改进后的暗目标算法,以及基于逐像元角度数据的6S查找表,对南宁市2014年1月14日、15日、16日HJ-1CCD数据进行气溶胶光学厚度反演。反演结果与ARONET地基观测数据进行验证,表明该算法有较高反演精度,相关系数为0.865,同时与MODIS气溶胶反演结果进行比较。结果表明,经过HJ-1CCD数据反演的气溶胶光学厚度可作为气溶胶时空分布的实时监测手段。     

海藻酸代谢菌的筛选及其性能研究

中国海岸线经常出现由海藻引起的海洋环境污染,海藻的有效利用有利于解决海洋环境问题。利用海藻发酵生产乙醇成为一项有前途的课题,但海藻中重要的多糖成分海藻酸却不能被利用。本课题以海藻酸钠为唯一碳源,初筛出了6株具有较强发酵能力的菌株,进一步摇瓶复筛,获得4株利用海藻酸生产乙醇能力较好的菌株,其中乙醇产率最高的为菌a。选取菌a进行菌株的形态观察及简单的生理生化特征分析,确定该菌株的类型。     

蒲河水生态修复工程与功效评估

"十二五"期间,沈阳市蒲河的污染控制与水生态修复工程同步实施。通过污水处理设施建设、水资源调控、生态廊道建设和河道水质改善技术示范等工程建设,实现了水质改善和水生态功能修复的目标。文章对重点工程的实施和功效进行了解析,总结了同类河流整治的科学对策和途径。