改性秸秆膨胀床与固定床吸附去除SO_4^(2-)

Removal of sulphate ions from aqueous solution by modified rice straw expanded- and fixed-bed columns

含硫酸根离子(SO42-)废水可对环境造成危害,在排放之前需降低SO42-浓度.本文利用改性秸秆阴离子吸附剂制备吸附柱,分别在膨胀床和固定床操作下进行动态吸附实验,研究改性秸秆阴离子吸附柱去除SO42-的性能.结果表明,在改性秸秆膨胀床操作中,膨胀率随流速提高而线性增大;随膨胀率的增加,膨胀床去除SO42-的穿透时间缩短,柱吸附量降低,膨胀率不宜大于25%;在改性秸秆固定床操作中,随高径比的增加,吸附柱去除SO42-的穿透时间延长;而随进水SO42-浓度和流量的增加,床层工作时间显著缩短;在实验流量下,膨胀床的处理效果略优于固定床.SO42-解吸实验表明,0.1 mol/L NaOH溶液解吸效果最佳,是合适的吸附柱再生液.

Sulphate（SO42-） in wastewater should be reduced before discharge because high concentration of SO42- could cause pollution problems to surrounding environment. In present study, the modified rice straw as anionic sorbent was used to prepare expanded- and fixed-bed columns for sulphate removal. The breakthrough curves were analyzed by Thomas model to investigate the column adsorption performance. The results showed that, for expanded-bed operation, the expansion ratio linearly increased with upflow volecity. The maximum expansion ratio of less than 25% was recommended because the breakthrough time and column adsorption amount both decreased with the rise of expansion ratio. For fixed-bed operation, either increase of influent sulphate concentration or flow rate would shorten the breakthrough time. However, with the increase of of height-diameter ratio of the column, the fixed-bed service time was extended. Under experimental flow rate, expanded-bed provided better adsorption of sulphate than fixed-bed. Additionally, 0.1 mol/L NaOH solution was the most appropriate regeneration agent under experimental conditions.