改性沸石对Cr(Ⅵ)的吸附作用研究

研究了改性沸石对Cr（Ⅵ）吸附的影响因素,即研究了溶液酸度、吸附时间、吸附剂用量和Cr（Ⅵ）的初始浓度对吸附的影响．结果表明：溶液的pH值是影响吸附的主要因素;离子交换和表面络合反应是主要吸附形式;改性沸石对Cr（Ⅵ）的吸附符合Langmiur吸附等温式,属于单分子层吸附．     

高锰酸钾改性对活性炭吸附Cr(Ⅲ)的影响

采用KMnO4对活性炭进行改性,考察了KMnO4改性对活性炭吸附Cr(Ⅲ)的影响。结果表明,在pH6.0的条件下,采用KMnO4改性可提高活性炭对Cr(Ⅲ)的吸附去除率,尤其是在低pH下提高得更为明显;当KMnO4浓度为0.04mol/L时,得到的改性活性炭AC-4的吸附性能最好;在pH=6.0的条件下,与未改性活性炭相比,改性活性炭对Cr(Ⅲ)的吸附速率明显提高,25℃时AC-4的饱和吸附量提高了43%;升高温度能明显提高改性活性炭对Cr(Ⅲ)的吸附能力,40℃时AC-4对Cr(Ⅲ)的饱和吸附量是25℃时的3.61倍。改性活性炭对Cr(Ⅲ)的吸附符合Langmuir单分子层吸附规律。     

改性膨润土吸附处理含Cr（Ⅵ）废水的研究

用阳离子表面活性剂十六烷基三甲基溴化铵（CTMAB）对钙基膨润土进行活化改性,并用制备的改性膨润土对含Cr（VI）模拟废水进行吸附实验,研究了改性膨润土去除模拟水样中重金属Cr（VI）的适宜条件。结果表明,用质量分数为5%的CTMAB溶液改性后的膨润土去除Cr（VI）效果较好,当改性膨润土用量为10g/L、搅拌时间30min、pH值为3～5时、有机膨润土对含Cr（VI）废水的去除率超过85%。     

改性膨润土去除水中Cr(Ⅵ)的研究

研究了膨润土的改性方法及改性膨润土对水中Cr(Ⅵ)的吸附性能,结果表明,改性膨润土较原土具有更高的离子交换能力和吸附能力,溴化十六烷基三甲铵(CTMAB)改性膨润土综合效果最好,水中残留的CTMAB对处理水未造成二次污染。     

石墨烯负载零价纳米铁材料的合成及去除水中Cr(VI)的研究

以石墨粉为原料,采用改良Hummers方法合成石墨烯,然后通过液相还原法制备出石墨烯负载纳米铁材料(Graphene-supported nanoscale zero-valent iron,G-nZVI),借助扫描电子显微镜(SEM)、红外光谱分析仪(FTIR)进行表征,并以G-nZVI为反应材料,研究其对水体中Cr(VI)的去除效率,结果显示:室温下,当G-nZVI投加量为0.4g/L,Cr(VI)的初始浓度为20 mg/L,初始pH值为3.0时,Cr(VI)的去除率在2h内可以达到95%以上。G-nZVI具有磁性,使用后可通过外加磁力除去,以防对水体的二次污染,具有较好的应用前景。     

膨润土对重金属离子Pb~(2+),Zn~(2+),Cr(VI),Cd~(2+)的吸附性能

试验研究了pH值、吸附时间和吸附剂用量对膨润土吸附重金属离子Pb2 ,Zn2 ,Cr(VI)和Cd2 的影响.结果表明,在本试验的pH值、吸附时间及吸附剂用量条件下,膨润土对Pb2 ,Zn2 ,Cd2 的吸附效果均优于其对Cr(VI)的吸附效果;pH值是影响上述吸附的重要因素,离子交换和表面络合是上述吸附的主要形式.     

改性沸石对废水中锰的吸附研究

采用吸附法去除水体中重金属锰,以NaOH对天然沸石改性,对含Mn的水体进行处理,通过单因素实验系统考察了改性沸石用量、吸附时间、初始浓度、温度对吸附效果的影响,研究结果表明在25℃,吸附剂用量为1.0 g,吸附时间120 min,对初始浓度为1.0 mg/L时,锰的去除率可达到99.3%,最大吸附容量达到9.93 mg/g。     

改性沸石吸附处理氨氮废水试验研究

在静态条件下研究了改性沸石对氨氮的吸附特性,考察了不同条件下改性沸石对含氨氮废水的处理能力。结果表明：热改性温度为500℃、pH值为7、改性沸石加入量为30g／L、吸附时间120min条件下,改性沸石对氨氮的去除率可达95％以上。     

十二烷基苯磺酸钠改性沸石吸附甲基橙的研究

以表面活性剂十二烷基苯磺酸钠改性天然沸石,对废水中甲基橙进行吸附,以紫外可见分光光度计分析最佳吸附条件,结果表明：在改性沸石的用量为20g/L、吸附时间为100min、温度为35℃、pH值为4.2时,十二烷基苯磺酸钠改性沸石对甲基橙溶液（10g/L）的吸附率达到了92.8%,吸附符合Langmuir等温方程。     

优势菌的EPS还原去除Cr(Ⅵ)的机理分析

以前期研究得到的一株还原Cr(Ⅵ)的优势菌Brevibacillus sp.为研究对象,并利用超声波法获得其胞外多聚物(EPS),分析了EPS对Cr(Ⅵ)的还原吸附贡献。试验结果表明:优势菌的EPS对Cr(Ⅵ)和总Cr的吸附去除率分别为18.58%和21.12%,吸附贡献率分别为48.49%和64.75%。对于完整菌体而言,EPS是发生Cr(Ⅵ)吸附的主要位点,其对Cr(Ⅵ)具有较好的还原作用。研究成果对于推动优势菌还原去除Cr(Ⅵ)机理的进一步探究奠定了基础。     

Batch Cr(VI) removal by polyacrylamide-grafted sawdust: Kinetics and thermodynamics

Batch sorption studies have been carried out to determine the effect of adsorbent dose, initial sorbate concentration and pH on the adsorption of Cr(VI) on polymer-grafted sawdust. The process was found to be pH, temperature and concentration dependent. An empirical relationship has been obtained to predict the percentage Cr(VI) removal at any time for known values of sorbent and initial sorbate concentration under observed test conditions. The effect of diverse ions has been studied and it is found that there is very little effect on the sorption of Cr(VI). The process was found to be exothermic with a maximum adsorption of 91.0% at 30°C for an initial concentration of 100 mg l⁻¹ at pH 3. The process follows first-order kinetics and the data fits the Freundlich adsorption isotherm. Thermodynamic parameters were also evaluated. Desorption studies confirmed that adsorbent can be effectively regenerated using 0.2 M NaOH and 0.5 M NaCl and can then be reused.     

氯化钠改性沸石吸附水中苯酚的研究

在ｐＨ为５￣７的条件下,经氯化钠改性后的钠型沸石对水中的苯酚有较强的吸附能力,该吸附剂市备工艺简单、价格低廉,可用于微污染含酚水的处理。     

A study of Cr(VI) and NH4+adsorption using greensand (glauconite) as a low‐cost adsorbent from aqueous solutions

This paper investigates the removal of Cr(VI) and NH⁴⁺ from aqueous solutions using greensand (glauconite). The effects of adsorbent dosage, contact time, initial Cr(VI) and NH⁴⁺ concentrations, and pH were investigated in batch experiments. The results show that these parameters influenced Cr(VI) and NH⁴⁺ removal using glauconite considerably. Pseudo‐first‐order, pseudo‐second‐order and intraparticle diffusion kinetic models were applied to explain the kinetic data, and the pseudo‐second‐order model achieved good agreement. The equilibrium isotherm data are coordinated with the Freundlich, Langmuir models, Temkin and Dubinin–Radushkevich; the Freundlich model proved most best suitable. The removal efficiency of Cr(VI) and NH₄⁺ were 12.21 mg/g (54% at pH 3) and 19.24 mg/g (77.08% at pH 7). All in all, the results showed that the adsorption process on glauconite could be used as an effective method for removing Cr(VI) and NH⁴⁺ from aqueous solutions.     

磁性锆铁改性沸石吸附疏浚余水中磷酸盐的特性

采用共沉淀法制备了磁性锆铁改性沸石,在研究其对疏浚余水中磷酸盐吸附特性的基础上,采用X射线衍射仪(XRD)表征其结构,探讨吸附磷的特性。结果表明,Langmuir等温吸附模型、准二级动力学模型和颗粒内扩散模型均可以较好地描述磁性锆铁改性沸石对疏浚余水中磷酸盐的吸附特征。当吸附剂投加量为18 mg/L、pH值为7时,疏浚余水中磷酸盐的饱和吸附量为11. 4 mg/g(以磷计);当pH值为5～7时,磁性锆铁改性沸石对磷酸盐的吸附效果较好,偏碱性条件下吸附量明显下降;当水温在10～30℃时,对磷酸盐的吸附效果随温度的升高而增加;磁性锆铁改性沸石吸附水中磷酸盐的过程属于化学吸附。     

Mn(II)、Cr(III)在黄土上共存吸附特性研究

重金属是土体污染中最重要的污染物质之一,土中的重金属污染往往是复合污染的形式。通过一系列室内试验,研究了锰铬重金属共存时在黄土上的吸附特性。在Mn(II)、Cr(III)重金属复合体系中,Mn(II)在黄土上的吸附明显受到抑制,吸附量减小14.6%~46.5%,而Cr(III)在黄土上的吸附基本不受Mn(II)的影响。Mn(II)的吸附能较好地符合Langmuir模型,受Cr(III)的抑制而不能很好地符合Fredunlich、D-R模型,Cr(III)的吸附仍能较好地符合Fredunlich、D-R模型。在pH=5~7酸性条件下Cr(III)促进了Mn(II)在黄土上的吸附,Mn(II)对Cr(III)的吸附稍有抑制;在碱性条件下,Cr(III)基本不受影响能完全被去除,而Mn(II)的吸附受到很大的抑制作用。重金属本身的物理属性比如水解常数大小以及黄土中的矿物成分都对Mn(II)、Cr(III)在黄土上吸附特性发挥了重要作用。     

Estimating the dual-enzyme kinetic parameters for Cr (VI) reduction by Shewanella oneidensis MR-1 from soil column experiments

Hexavalent chromium (Cr (VI)) contamination of soil and groundwater is considered a major environmental concern. Bioreduction of Cr (VI) to trivalent chromium (Cr (III)) can be considered an effective technology in remediating Cr (VI) contaminated sites. Among the Cr (VI) reducing bacteria, Shewanella oneidensis MR-1 (MR-1) is relatively effective. Reduction of Cr (VI) by MR-1 is defined by the dual-enzyme kinetic model. The feasibility of bioreduction of Cr (VI) is usually evaluated by performing batch experiments which may not accurately represent the subsurface environment. The objective of this paper is to present a rational approach to determine the dual-enzyme reaction kinetics of Cr (VI) reduction by MR-1 from continuous flow soil column experiments which more accurately simulate the subsurface environment. Kinetic parameters obtained from soil column data were found to be much smaller than that obtained from batch data. The stable enzyme induced reaction rate was found to be 127th and the average deactivating enzyme induced reaction rate was 117th of the corresponding values obtained from batch reactor data as reported in literature.     

水化硅酸钙对氯离子的吸附

通过化学分析法测定了水化硅酸钙(C-S-H)吸附氯离子的能力;通过核磁共振法和拉曼光谱法测定了水化硅酸钙的结构.结果表明:水化硅酸钙吸附氯离子的能力与其结构密切相关,水化硅酸钙平均链长约为4时,其吸附氯离子的能力最强;氯盐阳离子促进了水化硅酸钙链长的增加,使其吸附氯离子的能力增强;与钠离子相比,钙离子更能促进水化硅酸钙链长的增加,从而使其吸附更多的氯离子.     

Removal and recovery of Cr(VI) from polluted ground waters: a comparative study of ion-exchange technologies

The focus of this work has been the study of Cr(VI) removal from ground waters and the simultaneous concentration for its reuse using three different technological alternatives: anion-exchange resins, liquid-liquid extraction assisted by hollow fibre membranes and emulsion pertraction. The viability of the considered objectives, i.e., Cr(VI) separation (<0.5 g/m3) and concentration for reuse (>20,000 g/m3) has been checked and a comparative analysis of the three technologies has been performed. Although the flexibility and ease of operation of non-dispersive solvent extraction, anion-exchange resins and emulsion pertraction lead to higher velocities of chromium removal, yet still maintaining similar concentration efficiencies.