Mechanisms and factors affecting the adsorption of sodium alginate onto modified clays     

林勇新  曹西华  宋秀贤  王楠  俞志明 《中国海洋湖沼学报》2013,31(4):867-875

Algal organic materials (AOMs) are one critical factor affecting the efficiency of modified clays used for the mitigation of harmful algal blooms (HABs). This study was conducted to develop a deeper understanding of the mechanisms and factors affecting the adsorption of AOMs onto modified clays. Sodium alginate (polysaccharide) and kaolinite modified with polyaluminium chloride (PACl) were used as AOMs and modified clay model substances, respectively, and the effects of modifier dosage, contact time, solution pH and ionic strength were investigated through batch adsorption experiments. Kinetics revealed that the alginate adsorption rate was described well by a pseudo-second order model. PACl effectively enhanced the adsorption capacity of kaolinite and increased the adsorption rate, and the optimum additive amount of PACl was 5%. The experimental data fitted both the Freundlich and Langmuir adsorption equations well. The adsorption thermodynamics for alginate onto modified clays suggests that alginate adsorption is a spontaneous process. The adsorption of alginate onto modified clays was highly dependent on pH, with a decrease in adsorption observed with increased pH to 9.48, but the opposite was true above pH 9.48. Finally, adsorption increased with increasing ionic strength.  相似文献   

Adsorption of Heavy Metal Ions, Dyes and Proteins by Chitosan Composites and Derivatives- A Review     

LIU Bingjie  WANG Dongfeng  YU Guangli  MENG Xianghong 《青岛海洋大学学报(英文版)》2013,(3):500-508

Chitosan composites and derivatives have gained wide attentions as effective biosorbents due to their low costs and high contents of amino and hydroxyl functional groups. They have showed significant potentials of removing metal ions, dyes and pro- teins from various media. Chemical modifications that lead to the formation of the chitosan derivatives and chitosan composites have been extensively studied and widely reported in literatures. The aims of this review were to summarize the important information of the bioactivities of chitosan, highlight the various preparation methods of chitosan-based active biosorbents, and outline its potential applications in the adsorption of heavy metal ions, dyes and proteins from wastewater and aqueous solutions.  相似文献   

Evaluation of coal bed methane content using BET adsorption isotherm equation     

ZHANG Yi  FAN Xiaomin  HAN Xue  NAN Zeyu  XU Jun 《世界地质(英文版)》2012,15(1):74-77

Coal bed methane is unconventional raw natural gas stored in coal seam with considerable reserves in China.In recent years,as the coal bed methane production,the safety and the use of resources have been paid more attentions.Evaluating coal bed methane content is an urgent problem.A BET adsorption isotherm equation is used to process the experimental data.The various parameters of BET equation under different temperatures are obtained;a theoretical gas content correction factor is proposed,and an evaluation method of actual coal bed methane is established.  相似文献   

黄河包头段常见离子对重金属在沉积物上吸附影响机制研究   总被引：6，自引：3，他引：3  

薛红喜  何江  樊庆云  吕昌伟  孙英  梁英  白萨茹莉  沈丽丽 《地理科学》2008,28(3)

常见阴阳离子对重金属在黄河包头段相对清洁河段表层沉积物中的吸附影响研究结果表明,不同的环境离子浓度范围内,起主导作用的影响机制不同,黄河包头段水环境中Na 、Mg2 和Ca2 对Zn2 的吸附影响较大,K 对Cu2 、Pb2 、Zn2 和Cd2 吸附影响均较大,Cl-、SO2-4对Cu2 、Pb2 、Zn2 和Cd2 的吸附影响均较小,而HCO-3;对Pb2 的影响较小,对Cu2 、Zn2 、Cd2 的吸附影响较大.  相似文献   

天然磁铁矿化学改性及其在水体除砷中的应用   总被引：4，自引：2，他引：2  

吴昆明  郭华明  魏朝俊 《岩矿测试》2017,36(1):32-39

铁氧化物及其复合氧化物(如菱铁矿、水铁矿)的表面电荷高、比表面积大,在特定条件下对亚砷酸盐和砷酸盐有较强的结合能力和亲和性,以铁氧化物作为吸附剂处理高砷水已经成为研究热点之一。天然磁铁矿的主要成分为Fe_3O_4,但其本身活性较弱,直接应用于处理高砷水的除砷率低。本文对天然磁铁矿采取酸化、碱化、不同温度灼烧、不同灼烧时间等简易的方法进行改性,达到有效去除水中砷的目的。实验结果表明:经0.5 mol/L盐酸浸泡、150℃灼烧10 min的改性磁铁矿分别处理As(Ⅲ)溶液和As(Ⅴ)溶液时,As(Ⅴ)去除率达98%,吸附能力显著增强,达到预期目标;溶液中As(Ⅲ)浓度从1000μg/L下降到250μg/L,去除率达75%,即As吸附能力明显优于未改性的天然磁铁矿,与其他改性铁矿除砷能力相近,而改性方法更加简便、易行。本文研究的改性天然磁铁矿吸附剂为控制高砷水的砷含量提供了一种切实可用的吸附材料。  相似文献   

Application of low-pressure gas adsorption to nanopore structure characterisation of organic-rich lower Cambrian shale in the Upper Yangtze Platform,South China     

L. Chen  K. Liu  P. Wang  F. Gao  T. Hu 《Australian Journal of Earth Sciences》2017,64(5):653-665

The pores in shales are mainly on a nanometer scale, and the pore-size distribution is vital with regard to the preservation and exploitation of shale gas. This study focuses on the organic-rich lower Cambrian black shale in the Upper Yangtze Platform, South China and investigates their TOC, mineralogical composition and nanopore structure. Low-pressure N₂ and CO₂ adsorption experiments were conducted at 77.35 K and 273.15 K, respectively, and the nanopore structures were characterised by the modified Brunauer–Emmett–Teller, Dubinin–Radushkevich, t-plot, Barrett–Joyner–Halenda and density functional theory (DFT) methods. The results indicate the following. (1) The lower Cambrian shale has a high TOC content (1.77–7.23 wt%) and a high quartz content (27.7–51.6 vol%). The total specific surface area varies from 12.02 to 28.87 m²/g. Both the total specific surface area and quartz content are positively associated with the TOC content. (2) Shale samples with a higher TOC content have a greater number of micropores, resulting in more complicated nanopore structures. Micropore volumes/surface areas and non-micropore surface areas all increase with increasing TOC content, indicating that TOC is the key factor determining the nanopore structure of the lower Cambrian shale. (3) A combination of N₂ and CO₂ adsorption provides the most suitable detection range (～0.3–60 nm) and is both highly reliable and accurate with regard to nanopore structure characterisation.  相似文献   

电流对钋青霉菌吸附和固定铅离子的响应机制     

王明粲  郝瑞霞  丁杨 《岩石矿物学杂志》2017,36(6):858-864

重金属铅污染是一种主要的环境污染类型,对生态以及人类健康存在着极大的威胁。如何修复铅污染是目前亟待解决的关键性问题。在众多的铅污染修复方法中,微生物修复法具有独特的优势。本实验中所使用的钋青霉菌是已被验证的对铅具有高耐受度和高吸附率的优秀菌种。在此基础上,本实验的主要研究目的在于进一步提高该菌种对铅的吸附、固定能力。实验采用双室电解池体系,分组设置0.5 V至1.5 V的梯度槽压,以观察不同电压下电流对钋青霉菌生长环境及对铅离子吸附作用的影响。实验结果表明,电流既可能促进也可能抑制钋青霉菌对铅离子的吸附和固定作用,其作用结果与外加电压的大小有关,在1.0~1.25 V的最适电压区间下,电流能增强钋青霉菌对铅离子的吸附和固定能力。  相似文献   

不同钠吸附比含水介质中胶体迁移-沉积动力学          下载免费PDF全文

李海明  赵雪  马斌  李子琛  佟琪 《水文地质工程地质》2011,38(6):90-95

以滨海含水介质中天然胶体为研究对象,采用自行设计的室内土柱装置,研究不同钠吸附比胶体在滨海含水介质中迁移动态特征,测定了胶体沉积动力学曲线,计算了胶体总沉积率和沉积速率常数,最后对胶体迁移沉积机理进行了探讨。研究结果表明,胶体的穿透曲线与示踪离子相比,存在一个临界孔隙体积数(临界点),在临界点之前胶体的迁移速度大于示踪离子,之后则相反;胶体未发生完全穿透,钠吸附比SAR为0,2.85和∞;出水胶体最大相对浓度为0.65,0.16和0.70;胶体在含水介质迁移过程中发生了沉积,沉积量随孔隙体积数的增加而增加。胶体在含水介质中迁移的总沉积率分别为50.96%、87.95%和54.24%。钠吸附比SAR=2.85时沉积动态曲线为直线,沉积速率常数为0.151h-1,而钠吸附比SAR为0和∞时胶体沉积动态曲线为分段直线,拐点前后胶体沉积速率常数分别为0.072 h-1、0.048h-1和0.211 h-1、0.194 h-1。研究结果用双电子层理论可以很好地解释。  相似文献   

瓦斯压力对煤系页岩瓦斯吸附特性影响核磁共振谱试验研究     

唐巨鹏  田虎楠  于宁  丁佳会 《岩土力学》2016,37(Z2):203-208

瓦斯压力是影响煤系页岩瓦斯吸附特性的关键因素。以阜新高瓦斯矿井清河门矿煤系页岩为研究对象,采用低场核磁共振（NMR）谱技术,通过向放有试样的夹持器中不断充入瓦斯,模拟煤系页岩瓦斯集聚赋存过程。以核磁共振T2谱幅值积分作为反映瓦斯吸附量定量化指标,从微细观角度定量研究瓦斯压力对吸附态和游离态瓦斯量影响规律。试验结果表明,（1）两个截止阈值确定了吸附态和游离态瓦斯T2谱曲线范围;（2）瓦斯压力对煤系页岩吸附态和游离态瓦斯增量均有显著影响。吸附态瓦斯增量变化受控于煤系页岩和瓦斯分子间作用力,而游离态瓦斯增量则主要与煤系页岩孔隙结构有关;（3）吸附态瓦斯量与瓦斯压力间关系符合朗格缪尔等温吸附方程,而游离态瓦斯与瓦斯压力呈3次函数关系;（4）以瓦斯T2谱均值变化幅度定量描述孔隙平均半径扩胀变形程度,随瓦斯压力增加,煤系页岩中～大孔隙结构均发生显著扩胀,平均半径增加1.47倍,而微孔隙结构尺寸未见明显变化。  相似文献   

湘西北下古生界海相页岩储层特征与含气性分析     

唐书恒  范二平  张松航  姜文 《地学前缘》2016,23(2):135-146

基于野外地质和钻井资料,结合相关实验测试结果,对湘西北地区下古生界海相页岩储层特征进行了深入研究,并探讨了页岩甲烷含气性及影响因素。结果表明：牛蹄塘组黑色页岩以深水陆棚斜坡相沉积为主,厚度范围为50~250 m;龙马溪组为闭塞海湾沉积,底部黑色页岩发育。两组页岩有机质类型均属于Ⅰ型,有机碳含量平均为3.57%和1.16%,热演化程度较高,平均达2.61%和2.08%。受沉积环境和成岩作用影响,两组页岩均具有高石英、低黏土、少量碳酸盐矿物的组成特征。页岩储集空间可划分为3大类：矿物基质孔、有机质孔、微裂缝。受有机质和黏土矿物等因素影响,页岩内部孔隙结构参数各不同,但主体上孔径小于50 nm的微孔和中孔提供了大部分比表面积和孔体积,为气体存储主要场所。牛蹄塘组页岩甲烷最大吸附量平均为1.98 cm3/g;龙马溪组页岩甲烷最大吸附量较低,为1.16 cm3/g。其中有机质与黏土矿物对页岩甲烷吸附量均有一定的贡献,而过高的成熟度和含水量可导致页岩吸附能力下降。  相似文献