改性明矾浆吸附剂的制备及其除镉性能研究

Alum plasma modification and its adsorption characteristics of cadmium

以明矾生产中产生的废弃物明矾浆为原材料,采用热酸改性、热碱改性、焙烧改性和巯基化改性4种方法进行活化处理,得到新型除镉(Cd)吸附剂.同时,考察了Cd2+初始浓度、pH值和吸附剂投加量对改性明矾浆吸附去除Cd2+的影响,并采用扫描电镜(SEM)、比表面积(BET)、用红外光谱(IR)等仪器对吸附剂进行表征.结果表明,热碱改性明矾浆具有较好的吸附Cd2+的性能,其饱和吸附量为5.41mg·g-1,而原明矾浆的饱和吸附量仅为0.40mg·g-1;热酸改性、焙烧改性和巯基化改性3种明矾浆对Cd2+的吸附性能与原明矾浆相比没有显著差异.改性明矾浆对Cd2+的吸附规律符合Langmuir等温方程式,其吸附机制主要为表面吸附.溶液pH值会显著影响改性明矾浆对Cd2+的吸附量和吸附率.综合而言,在pH≥7时,热碱改性明矾浆具有较好的去除Cd2+能力.

This research was devised to modify alum from alum production so that the cadmium removal adsorbents can be obtained. First, Alum plasma, a waste tailing of alum production, was employed as raw materials and processed via four experimental approaches, which include heat acid activation, heat alkali activation, heat activation and thiol modified activation sorbents. Then, the obtained Cd removal sorbents were examined, and their impacts onpH values, input of alum plasma and initial Cd^2＋ concentration on the sorption capacity were assessed. Furthermore, the modified alum plasmas were characterized using scanning electron microscopy microanalysis （SEM） , specific surface area （BET） and infrared spectra （IR）. The research outcomes demonstrated that the heat alkali activation alum plasma enhanced Cd^2＋ removal capacity substantially, with the maximum Cd^2＋ adsorption capacity of the alum plasma of 5.41 mg·g^-1 , a lot higher than the original alum plasma of 0.40 mg·g^-1. Moreover, the Cd^2＋absorption capacity of the heat alkali activation alum plasma complied with the Langmuir isotherm, showing as surface complexation. Likewise, solution pH significantly affected the sorption capacity and the removal efficiency. To summarize, heat alkali activation alum plasma has great advantages in dealing with the wastewater of high Cd^2＋ concentration when pH ≥7.