阴-阳离子有机膨润土协同吸附作用及其机理研究

 合成并研究了一系列阴-阳离子有机膨润土对水中苯酚、苯的吸附作用及其机理.结果表明,阴-阳离子有机膨润土对水中有机物具有协同吸附作用,其作用大小与改性时所用表面活性剂的种类、组成、配比及有机物本身的性质有关;对苯酚的吸附符合Langmuir和Freundlich吸附等温式,是分配作用(partition)和表面吸附(adsorption)共同作用的结果,分配作用的贡献率随改性时阴离子表面活性剂加入量的增大而增大;对水中苯的吸附以分配作用为主,分配系数大于原土及单阳离子有机膨润土,且与有机碳含量呈正相关.     

阴-阳离子有机膨润土吸附水中苯胺、苯酚的性能

首次用阴、阳离子表面活性剂改性膨润土 ,制得一系列阴 -阳离子有机膨润土 ,表征了有机膨润土的结构特征 ;研究了阴 -阳离子有机膨润土吸附水中苯酚、苯胺等有机物的性能及影响因素 ,并初步探讨了其吸附机理 .结果表明 ,阴 -阳离子有机膨润土的层间距和有机碳含量与改性时阴、阳离子表面活性剂的组成和配比有关 ;阴 -阳离子表面活性剂在有机膨润土中形成了增溶 (分配 )作用较强的有机相 ,从而对水中的有机污染物产生协同去除效应 .     

有机膨润土吸附水中有机物的盐效应及其机理

 实验室模拟研究了一系列双阳离子有机膨润土对水中不同浓度的对硝基苯酚的吸附性能.结果表明,土样有机碳含量越高,对硝基苯酚初始浓度越低,有机膨润土对其吸附性能越好.试验了多种无机盐对有机膨润土吸附性能的影响,发现盐效应与离子荷径比和膨润土改性表面活性剂有关.无机盐阳离子相同时,盐效应与阴离子荷径比成反比;无机盐阴离子相同时,与阳离子荷径比成正比.单阳离子有机膨润土的盐效应呈负效应,长短碳链比例相当的双阳离子有机膨润土的盐效应呈正效应.     

双阳离子有机膨润土吸附处理水中有机物的性能

 分别用长碳链季铵盐（ 如溴化十二烷基三甲铵、溴化十四烷基苄基二甲铵、溴化十六烷基三甲铵、溴化十八烷基三甲铵） 和短碳链季铵盐（ 如溴化四甲基铵） 按一定配比混合改性膨润土，制得一系列双阳离子有机膨润土．研究了双阳离子有机膨润土吸附水中对硝基苯酚、苯酚、苯胺的适宜条件、性能、作用机理．结果表明，双阳离子有机膨润土的层间距、有机碳含量和对有机物的吸附性能与改性时长、短碳链季铵盐的组成及配比有关，水中有机物的去除效果还与其本身的性质有关；所用的双阳离子有机膨润土对有机物的吸附符合 Freundlich或 Langmuir等温式，是表面吸附作用和分配作用共同作用的结果．     

苯酚、苯在水／阴离子有机膨润土界面的环境行为研究

研究了苯酚在水／阴离子有机膨润土界面的吸附行为，初步探讨了阴离子有机膨润土对苯酚、苯的吸附性能、机理及影响因素。结果表明，阴离子表面活性剂改性后，膨润土中有机碳含量增加了10～38倍，对苯酚、苯的吸附能力大大提高。水中苯酚、苯在水／阴离子有机膨润土界面的吸附行为主要分配作用所致，其吸附等温线呈线性。     

改性膨润土粉末对克百威的吸附

分别用季铵盐阳离子表面活性剂十六烷基三甲基溴化铵(CTMAB)和阴离子表面活性剂十二烷基苯磺酸钠(SDBS)改性钠基膨润土,研究改性膨润土吸附水中氨基甲酸脂类农药克百威的效果、机理及主要影响因素。结果表明,改性膨润土的有机碳含量和用土量影响其对克百威的吸附去除率。表面活性剂通过插层进入膨润土间,有效扩张了膨润土的层间距,有机插层效果明显。100CTMAB-10SDBS膨润土为最佳的吸附剂类型,最佳用土量20.00 g/L,吸附平衡时间为3 h,平衡去除率为92.60%。改性膨润土对克百威的吸附符合Freundlich模型,变形公式的相关系数在98%以上。     

阳-非离子混合表面活性剂对沉积物吸附硝基苯的影响

研究了非离子表面活性剂Triton X-100、阳离子表面活性剂氯化十六烷基吡啶(CPC)及其混合物在沉积物上的吸附行为,探讨了它们对沉积物吸附硝基苯的影响.结果表明,CPC和Triton X-100在沉积物上的吸附等温线均为非线性,吸附量随着平衡浓度的增加急剧增加,并迅速达到最大吸附量.低浓度CPC能明显增加Triton X-100在沉积物上的吸附,而高浓度的CPC则显著降低Triton X-100在沉积物上的吸附.Triton X-100略微降低CPC在沉积物上的吸附.在表面活性剂浓度较低的实际环境中,无论是阳离子或非离子表面活性剂,将主要被土壤或沉积物吸附并固定.硝基苯在沉积物上的吸附等温线为线性.CPC和Triton X-100促进沉积物对硝基苯的吸附,CPC-Triton X-100混合表面活性剂溶液能进一步增强沉积物对硝基苯的吸附.因此,阳离子和非离子混合表面活性剂可增强土壤或沉积物对有机污染物的吸附固定能力,也可以用来制备有机膨润土以提高其吸附处理废水的性能.     

苯蒸气在有机膨润土上的吸附性能及机理研究

 对比研究了膨润土和有机膨润土的结构及其对苯蒸气的吸附性能.绘制了不同温度下 苯蒸气在有机膨润土(空气中干燥)上的吸附等温线,计算出苯蒸气的吸附系数及吸附热,并初 步推测其吸附机理.结果表明,苯蒸气在原土上的等温吸附曲线呈非线性,其吸附热为(30.6kJ /mol,主要吸附机理为矿物质表面吸附.表面活性剂改性后,膨润土的吸附能力远大于原土,苯 蒸气在有机膨润土上的吸附等温线呈线性,其吸附热在-29.7～ -20.8kJ/mol之间,吸附作用中 有机质的分配作用贡献率较大,吸附系数(K_d)与有机碳含量(_foc)成正相关.     

双阳离子有机膨润土吸附水中有机物的特征及机理研究

研究了双阳离子有机膨润土吸际水中硝基苯酚，苯酚，苯胺的特征及机理。结果表明，双阳离子有机膨润土对水中有机物的等温吸附曲线符合Ｌａｎｇｍｕｉｒ和Ｆｒｅｕｎｄｌｉｃｈ吸附等温式，是分配作用和表面吸附共同作用的结果。首次定量描述了分配作用和表面吸附在双阳离子有机膨润土吸附有机物中的相对贡献率；     

苯蒸气在有机膨润土上的吸附行为研究

探讨了苯蒸气在膨润土原土、单阳离子有机膨润土及阴－阳离子有机膨润土上的吸附性能、机理及影响因素。结果表明，有机膨润土对苯蒸气有良好的吸附性能，两种阴－阳离子有机膨润土对气态苯的吸附能力大于单阳离子有机膨润土，表现出较强的协同吸附作用；有机膨润土对气态苯的吸附作用主要由分配作用所致，等温吸附线呈线性，吸附系数（Kd)与有机膨润土的有机碳含量（foc）成正相关，与温度及比表面积成负相关，吸附速率（r)与有机碳含量成正相关。有机膨润土具有较大的开发、应用潜力。     

Partition of polycyclic aromatic hydrocarbons on organobentonites from water

ＩｎｔｒｏｄｕｃｔｉｏｎＴｈｅａｌｕｍｉｎｏｓｉｌｉｃａｔｅｓｈｅｅｔｓｏｆｂｅｎｔｏｎｉｔｅｐｏｓｓｅｓｓａｎｅｔｎｅｇａｔｉｖｅｅｌｅｃｔｒｉｃａｌｃｈａｒｇｅｃｏｍｐｅｎｓａｔｅｄｆｏｒｂｙｉｎｏｒｇａｎｉｃｅｘｃｈａｎｇｅａｂｌｅｃａｔｉｏｎｓ(ｅ.ｇ.,Ｎａ+ａｎｄＣａ2+),ｗｈｉｃｈｓｔｒｏｎｇｌｙｈｙｄｒａｔｅｄｉｎｔｈｅｐｒｅｓｅｎｃｅｏｆｗａｔｅｒ.Ｓｕｒｆａｃｅｐｒｏｐｅｒｔｉｅｓｏｆｎａｔｕｒａｌｂｅｎｔｏｎｉｔｅｃａｎｂｅｍｏｄｉｆｉｅｄｂｙｓｉｍｐｌｅｉｏｎｅｘｃｈａｎｇｅｗｉ…     

CTMAB/CPAM复合改性膨润土吸附水中苯酚和硝基苯

用十六烷基三甲基溴化铵(CTMAB)和阳离子型聚丙烯酰胺(CPAM)改性膨润土,制得系列CTMAB-膨润土(C-Bt)、CPAM-膨润土(P-Bt)和复合改性膨润土(C/P-Bt).采用XRD分析了各类有机膨润土的底面间距,并比较了它们吸附水中苯酚和硝基苯的性能.结果显示,C/P-Bt的底面间距大于相应的C-Bt和P-Bt,表明CTMAB与CPAM能同时层插到膨润土层间.C/P-Bt吸附性能优于C-Bt及C-Bt加P-Bt,在相同平衡浓度下(苯酚为7 045 mg/L,硝基苯为409 mg/L),60C/4%P-Bt对苯酚和硝基苯的吸附量分别为150 mg/g和69 mg/g,吸附量比60C-Bt分别提高了26%和28%,比60C-Bt加4%P-Bt分别提高了22%和26%,表现出明显协同吸附效应.这说明CTMAB在C/P-Bt层间的排列模式受CPAM的影响,形成了对有机物亲和能力更强的吸附介质.该新型有机膨润土在有机污染控制中有良好的应用前景.     

Chemical behavior of organic compounds in the interface of water/dual-cation organobentonite

The sorption behavior of polar of ionizable organic compounds,such as p-nitrophenol,phenol and aniline,in the water/organobentonite systems is investigated.Both adsorption and partition occur to the sorption of organic compounds to dual-cation organobentonites.The separate contributions of adsorption and partition to the total sorption of organic compounds to dual-cation organobentonites are analyzed mathematically in the first time.The factors to the contributions are also discussed.The results indicated that the contribution of adsorption and partition is related to the composition and ratio of dual-cation surfactants exchanging onto the bentonite.The sorption of organic compounds to dual-cation organobentonite is dominated by adsorption at low concentrations and by partition at high concentrations,making the organobentonites powerful sorbents for organic contaminants over wide range of concentrations.     

Adsorption of mixed cationic-nonionic surfactant and its effect on bentonite structure

The adsorption of cationic-nonionic mixed surfactant onto bentonite and its effect on bentonite structure were investigated. The objective was to improve the understanding of surfactant behavior on clay mineral for its possible use in remediation technologies of soil and groundwater contaminated by toxic organic compounds. The cationic surfactant used was hexadecylpyridinium bromide (HDPB), and the nonionic surfactant was Triton X-100 (TX100). Adsorption of TX100 was enhanced significantly by the addition of HDPB, but this enhancement decreased with an increase in the fraction of the cationic surfactant. Part of HDPB was replaced by TX100 which decreased the adsorption of HDPB. However, the total adsorbed amount of the mixed surfactant was still increased substantially, indicating the synergistic effect between the cationic and nonionic surfactants. The surfactant-modified bentonite was characterized by Brunauer-Emmett-Teller specific surface area measurement, Fourier transform infrared spectroscopy, and thermogravimetric-derivative thermogravimetric/differential thermal analyses. Surfactant intercalation was found to decrease the bentonite specific surface area, pore volume, and surface roughness and irregularities, as calculated by nitrogen adsorption-desorption isotherms. The co-adsorption of the cationic and nonionic surfactants increased the ordering conformation of the adsorbed surfactants on bentonite, but decreased the thermal stability of the organobentonite system.     

Sorption of BTEX mixtures to organobenonites

Organobentonites synthesized by replacing the metal ions in bentonite with cetyltrimethylammonium (CTMA) or tetramethylammonium cation(TMA) were investigated for their behaviors to sorb benzene, toluene, pxylene from water. The results served to distinguish the sorption mechanisms (adsorption or partition) of the two types of organobentonites. Bentonites modified with short-chain alkyl functional groups(e, g., TMA) sorb organic contaminants primarily by an adsorption process, in which the sorbed amount decreases with increasing steric hindrance of the organic compound and the process exhibits a competitive effect because of steric hindrance in multisolute systems. In contrast, the sorption of contaminants to organobentonites modified with long-chain alkyl groups (e. g., CTMA) occurs by partition process without exhibiting a competitive effect, and the additional organic compounds may induce a cosorptive effect. In the latter case, the measured distribution coefficients of organic compounds between organobentonites and water( log Kd ) are positively correlated with the octanol-water partition coefficients of the compounds (logKow) and the sorption process exhibits no competitive effect in multi-solute systems.