有机改性凹凸棒石对养猪废水中有机物的吸附研究

研究表征了十二烷基二甲基甜菜碱和十六烷基三甲基溴化铵改性凹凸棒石的结构,探讨了改性凹凸棒石对猪粪废水中的有机污染物的吸附性能及机理,并考察了改性剂修饰比例、废水p H、吸附剂的投加量对吸附过程的影响.结果表明,两种改性剂成功结合到了凹凸棒石表面,有机改性凹凸棒石的晶体结构未发生改变,但对有机污染物的吸附能力显著高于原土.两性和阳离子改性凹凸棒石吸附有机污染物的最佳参数为:修饰比例为100%,吸附剂浓度为16 g·L~(-1),p H=4(阳离子改性为6),对猪粪废水中COD的去除率分别达到88%和92%,吸附量分别达到79 mg·g~(-1)和82 mg·g~(-1).吸附过程均符合二级动力学模型(R20.998),两性和阳离子改性凹凸棒石对有机物的吸附分别符合Freundlich和Langmuir等温式.有机改性凹凸棒石的疏水性增强,提高了对有机污染物的吸附能力,其沉降性能良好,这使其作为一种吸附剂用于实际养猪废水的处理成为可能.

The adsorption of organics in swine wastewater by organo-attapulgite

The structure of attapulgite modified with dodecane-betaine (BS-12) and cetyltrimethylammonium bromide (CTMAB) was characterized. The adsorption for the organic contaminants in swine effluent by organo-attapulgite were studied, and the modified ratio, pH and the dosage of adsorbent were discussed. The results show that the surfactants were grafted on the surface of attapulgite, whose crystal structure was unaffected. The adsorption of organic contaminants by attapulgite was enhanced significantly when modified with BS-12 and CTMAB. The optimal conditions for adsorbing organic contaminant with amphoteric and cationic attapulgite were obtained:modified ratio was 100%, dosage of adsorbent were 16 g·L^-1.Meanwhile, when pH was 4 (pH of attapulgite modified with CTMAB was 6), the COD removal efficiencies in swine effluent with amphoteric and cationic attapulgite reached 88% and 92%, corresponding to the adsorption capacity of 79 mg·g^-1 and 82 mg·g^-1, respectively. The adsorption could be described by pseudo-second-order kinetics (R²>0.998).The adsorption features of amphoteric and cationic attapulgite was well fitted with Freundlich isotherm model and Langmuir isotherm model, respectively. When modified with BS-12 and CTMAB, the hydrophobicity of attapulgite increases, enhancing its adsorption to organic contaminant. Furthermore, the sedimentation of organo-attapulgite was good. Therefore, good adsorbability and settleability of organo-attapulgite make it practical in swine effluent treatment.