共查询到20条相似文献,搜索用时 140 毫秒
1.
2.
土壤有机质对镉在土壤中吸附-解吸行为的影响 总被引:33,自引:2,他引:31
研究了Cd^2+在红壤、黄泥土、乌栅土及去除有机质后的三种土壤中的吸附-解吸行为.结果表明,有机质的去除显著降低了三种土壤体系Cd^2+吸附-解吸平衡液的pH值,ApH范围为0.51到3.05.三种土壤中Cd^2+的吸附量大小为:乌栅土〉黄泥土〉〉红壤,与土壤有机质含量的顺序一致;去除有机质后土壤对Cd^2+的吸附量均明显下降,尤其是有机质含量高的黄泥土和乌栅土;三种土壤有机质对Cd^2+吸附的贡献率平均值分别为红壤43.75%、黄泥土544.77%、乌栅土993.76%.Cd^2+在所有土壤中的吸附均可用Freundlich方程来描述,相关系数均大于0.991,吸附亲和力的变化与吸附量大小的变化一致,n值在0.350到0.975之间变化.三种土壤中Cd^2+解吸量依次减少,红壤中Cd^2+解吸率均在50%以上,而黄泥土和乌栅土中解吸率最高为42%和19%;去除有机质后解吸率均在50%以上,且解吸量相差不大. 相似文献
3.
制备了锆氧化物(ZrO_2)含量分别为2.98%、7.81%、13.73%和33.70%的4种锆镁改性膨润土,并考察了锆负载量对锆镁改性膨润土吸附水中磷酸盐的影响.结果表明,较高的吸附剂投加量有利于水中磷酸盐被锆镁改性膨润土所吸附去除.锆镁改性膨润土吸附水中磷酸盐的动力学过程符合准二级动力学模型.锆镁改性膨润土对水中磷酸盐的吸附等温行为可以采用Langmuir、Freundlich和Dubinin-Redushckevich (D-R)等温吸附模型进行描述.增加溶液pH值不会导致锆镁改性膨润土对水中磷酸盐吸附能力的下降.锆镁改性膨润土对水中磷酸盐的吸附能力随其锆含量的增加而增加.但是,从总体上,锆镁改性膨润土中单位质量ZrO_2对水中磷酸盐的最大吸附量则随其锆含量的增加而降低.研究结果说明,锆镁改性膨润土适合作为一种吸附剂去除水中的磷酸盐,较高的锆负载量有利于增强锆镁改性膨润土吸附水中磷酸盐的能力,而较低的锆负载量则有利于提高锆镁改性膨润土中单位质量ZrO_2对水中磷酸盐的吸附能力. 相似文献
4.
5.
将吸附结晶紫后的废弃膨润土在氮气保护下600℃加热3 h,用HF和HCl洗掉其中的膨润土片层,得到了一种新型碳纳米材料.对碳材料进行了XRD、TEM、N2吸附-脱附表征,研究结果显示,该材料石墨化程度较高,其2θ角在26.1°处有明显的峰衍射,接近于石墨烯在26.48°的峰;TEM表征结果显示碳材料为薄层皱褶结构.N2-BET测得所制材料比表面积为77.6 m2·g-1.对比了该碳材料和十六烷基三甲基溴化铵(CTMAB)改性膨润土以及减电荷四甲基氯化铵(TMA)改性膨润土常温下吸附硝基苯的效果,发现该材料对硝基苯吸附效果远胜于两种改性膨润土.吸附热力学实验显示吸附过程为放热和熵减少的自发过程. 相似文献
6.
有机膨润土吸附垃圾渗滤液中苯酚的研究 总被引:17,自引:0,他引:17
以溴化十六烷基三甲铵为改性剂制备有机膨润土,研究了有机膨润土吸附垃圾渗滤液中典型有机污染物苯酚的性能、条件及改性条件对吸附效果的影响。结果表明,有机膨润土对苯酚有很好的吸附效果,实验条件下对苯酚的去除率可达90%以上,pH值是影响有机膨润土吸附能力的主要因素,绘制了不同初始浓度的苯酚溶液在平衡浓度达国家工业废水的第二类污染物三级排放标准时,改性膨润土的用量曲线及吸附等温线,并得到投样量方程:y=0.1959x-0.2458,R^2=0.9751。 相似文献
7.
粘土改性条件的研究Ⅰ.膨润土的改性 总被引:12,自引:2,他引:12
考察了改性膨润土的致孔剂加入量、溴化十六烷基三甲胺 (CTMAB)加入量、CTMAB溶液浓度和吸附时间对CTMAB吸附量的影响 .测得加工后的膨润土对CTMAB的饱和吸附容量为 34 0 0± 30 0mg·1 0 0g- 1膨润土 .膨润土对CTMAB的吸附表现出Lang muir吸附特征 .6 0℃ ,当CTMAB的加入量为膨润土饱和吸附容量的 1 3— 1 5倍 ,CTMAB溶液浓度≥ 2mg·ml- 1,吸附时间超过 2 0h时 ,膨润土基本达到饱和吸附 .并考察了有机膨润土对于水中苯、甲苯、乙苯、邻二甲苯 (BTEX)的去除效果 . 相似文献
8.
膨润土负载壳聚糖修复土壤镉污染的效果 总被引:1,自引:0,他引:1
随着重金属污染土壤日益加剧,污染土壤修复和控制技术的研究越来越迫切.为利用膨润土原位修复土壤镉污染提供理论依据,采用平衡吸附试验研究了Cd2 在膨润土负载壳聚糖上的吸附行为.以90%脱乙酰度壳聚糖为原料,制备了膨润土负载壳聚糖颗粒吸附剂,用于吸附溶液中Cd2 .试验探讨了壳聚糖质量浓度对负载率的影响,结果表明,质量浓度3%的壳聚糖负载量最大,壳聚糖最大负载率达32.6%.吸附Cd2 最佳工艺条件是:壳聚糖与膨润土质量比为1∶20,膨润土负载壳聚糖颗粒吸附剂用量为15 g·L-1,溶液中Cd2 含量不大于200 mg·L-1, pH 值为6~8,吸附平衡时间为8 min,Cd2 去除率为99%.动态吸附Cd2 试验结果表明:质量浓度为 200 mg·L-1的含Cd2 溶液,流速为4~6 m(h-1,经壳聚糖-膨润土吸附剂一次处理后,溶液中Cd2 的残留量为0.7 mg(L-1. 相似文献
9.
膨润土对土壤腐殖质特性的影响 总被引:1,自引:0,他引:1
砂质土壤腐殖质含量低,影响了土壤肥力.文章通过田间条件下砂滤管试验,利用膨润土的吸附和粘结功能,研究了膨润土不同用量对土壤腐殖质特性的影响.结果表明:膨润土在促进松结态腐殖质分解、加速紧结态腐殖质合成方面发挥了重要作用,有利于增加土壤系统的内稳性.施用膨润土促进了紧结态和稳结态腐殖质中HA的积累,提高了HA/FA比.胡敏酸红外吸收光谱表明,膨润土能使其脂肪族物质增多、芳化度降低.膨润土具有提高土壤腐殖质含量,改善土壤腐殖质特性,从而提高了土壤肥力. 相似文献
10.
11.
12.
ABSTRACTNatural polymer Moringa oleifera seed as coagulant and bentonite clay as adsorbent were used for preparing novel composite coagulant. Results obtained from FTIR, SEM, TEM and P-XRD show that the bentonite clay and M. oleifera seed biopolymers physico-chemically interact with each other during the preparation of clay-polymer composite. The FTIR results show that the major functional groups present in bentonite clay and M. oleifera seed are integrated at nano levels in the novel composite to remove heavy metals from aqueous systems. The coagulo-adsorption using clay-polymer composite may be used for the adsorption of heavy metals ions from the aqueous systems. It becomes possible due to the structural characteristics of the clay crystallites together with the functional attraction of the biopolymer and it results in the formation of clay-polymer metal complexes. The clay-polymer nano-composite of M. oleifera seed and bentonite clay showed considerable cadmium, chromium and lead removal property. 相似文献
13.
Fr d rique Barbier Fr d ric Plassard G rard Duc Michelle Petit-Ramel 《Chemistry and Ecology》2002,18(3):177-186
In order to prevent contamination of subsoil and groundwater by leachates containing heavy metals, montmorillonite linings are used on landfill bottoms. It is therefore important to understand ion uptake by this clay. In this study we have performed percolation of lead(II) and cadmium(II) through columns filled firstly with a technical bentonite and then with a reference bentonite. Elution curves provide an evaluation of metals retention. After the percolation step, columns are cut and metal ions are extracted to evaluate influence of side effects and soil depth on metal uptake. Moreover retentions of lead(II) and cadmium(II) are compared. 相似文献
14.
Fre´de´rique Barbier Fre´de´ric Plassard Ge´rard Duc Michelle Petit-Ramel 《Chemistry and Ecology》2013,29(3-4):177-186
In order to prevent contamination of subsoil and groundwater by leachates containing heavy metals, montmorillonite linings are used on landfill bottoms. It is therefore important to understand ion uptake by this clay. In this study we have performed percolation of lead(II) and cadmium(II) through columns filled firstly with a technical bentonite and then with a reference bentonite. Elution curves provide an evaluation of metals retention. After the percolation step, columns are cut and metal ions are extracted to evaluate influence of side effects and soil depth on metal uptake. Moreover retentions of lead(II) and cadmium(II) are compared. 相似文献
15.
为揭示苏云金杆菌(Bacillus thuringiensis,简称Bt)富集重金属的可行性,考察重金属对Bt发酵的影响,以生物毒性较大的重金属镉(Cd)为研究对象,以城市污泥为培养基,研究了添加Cd(II)对Bt生长和晶体蛋白合成的影响,分析了Bt发酵过程中Cd有效态质量浓度的变化,利用傅立叶红外光谱(FTIR)和X线光电子能谱(XPS)初步探讨了Cd(II)在Bt表面吸附的作用机制。结果表明:培养基中外加Cd(II)对Bt生长的影响主要取决于Cd有效态质量浓度,污泥培养基在支持Bt生长和降低重金属有效态质量浓度上均明显优于常规培养基;Bt对Cd(II)有较好的耐受性,当Cd有效态质量浓度在20 mg.L-1以下时,Bt能较好地完成生长代谢过程;光谱学分析表明Bt对Cd(II)有少量吸附,吸附位点主要为羟基,少量C=O基团也可与吸附反应,可有效降低重金属的生物有效性。 相似文献
16.
17.
ABSTRACTVery important in adsorption processes is the preparation of material sorbents and from this reason, the impact of washing agent of raw sorbent was analysed. The adsorption capacity was studied in relation to the function of the equilibrium time, the amount of biosorbent and the initial metal(II) ions concentration. In this research for the sake of comparison, the sorptive properties of out-of-date coffee were compared to coffee washed with different agents (mineral acids and water). The scanning electron microscopy and Fourier transform infrared spectroscopy were used to characterise the biosorbents and to identify the functional groups that participated in metal(II) ions bonding. The obtained results clearly indicate that the out-of-date coffee are effective biosorbent for cadmium(II) and nickel(II) ions from aqueous solution. However, for metal(II) ions removal efficiency could influence sorbent preparation and nickel(II) ions were best adsorbed on coffee washed with water, but cadmium(II) ions on raw biosorbent (out-of-date coffee). The best results of sorption were achieved after the contact time of 30 and 60?min, respectively for cadmium(II) and nickel(II) ions. 相似文献
18.
19.
20.
The influence of pH, competitor ions (NaNO3) and aerobic and anaerobic stabilization of activated sludge on the cadmium uptake by activated sludge solids was investigated. Above 0.08 mg L‐1 cadmium in solution, biosorption was found to follow the Freundlich isotherm. Active cellular uptake of soluble cadmium does not appear to be a significant mechanism of the biosorption. In addition, the cadmium uptake is not completely reversible. The adsorption of cadmium by activated sludge seems to involve a physico‐chemical mechanism with especially weak electrostatic interactions with ion‐exchange reaction. The optimum adsorption pH was 7.5. Adsorption is influenced by sodium ion concentrations up to an equivalent conductivity of 10 000 μS cm‐1. Aerobic and anaerobic stabilization of activated sludge increase systematically the initial adsorption capacities. Respirometric measurements were done to evaluate the inhibitive effects of cadmium on activated sludge. Monod's equation and the equation of non‐competitive inhibition were used to describe the toxicity related to cadmium uptake. These two equations appear to be complementary. 相似文献