天然和巯基改性沸石吸附水溶液中重金属Hg^2＋的特征研究

Study on characterization of mercury sorption by natural and thiol modified zeolites

为了提高沸石对汞的吸附性,利用半胱胺盐酸盐对天然斜发沸石进行改性,制得巯基改性沸石。研究了吸附剂用量、pH值、温度、Hg2+浓度和吸附时间对沸石和巯基改性沸石吸附Hg2+的影响,并进一步研究了吸附机理。结果表明,巯基改性沸石吸附Hg2+受pH值、温度的影响较小,吸附机制主要是沸石表面的硫与Hg2+的化学反应。而天然沸石对Hg2+的吸附主要是离子交换作用,受温度、pH值等的影响较大,随温度的升高吸附量下降。整个吸附过程以较快的速度进行。天然沸石在吸附时间为1 h、巯基改性沸石在0.5 h时基本达到吸附平衡。吸附条件试验和Langmu ir等温吸附模型都表明,巯基改性沸石对Hg2+的吸附能力得到了很大的提高,吸附容量由8.06 mg/g提高到19.88 mg/g,提高了146.65%。

This work, using cysteamine hydrochloride to modify natural clinoptilolite zeolites, results in great enhancement of absorption capacity. The effects of absorber dosage, pH values, temperature, adsorption time and Hg^2＋ concentration on Hg^2＋ adsorption and adsorption mechanism are researched. The result shows that the mercury retention by the modified zeolite is attributed to the metal-chelating S functionality, while the one by the natural zeolite is cation exchange. The pH and temperature factors that have slightly effect on the modified zeolite adsorption could significantly affect the natural zeolite; the higher the temperature is, the lower the sorption rate is. Within a high rate of the adsorption process, the modified zeolite takes 0.5 h to reach the adsorption equilibrium, while the natural zeolite takes 1 h. The Langmuir isotherm model and the adsorption conditions experiment both indicate that the modification has greatly enhanced the adsorption capacity for Hg^2＋ , the maximum capacity is increased by 146.65% , from 8. 06 mg/g to 19.88 mg/g Hg.