茶叶基水合氧化铁吸附水体中Pb(Ⅱ)的性能

Sorption Characteristics of Tea Waste Modified by Hydrated Ferric Oxide Toward Pb( Ⅱ) in Water

采用原位沉积技术将水合氧化铁(HFO)负载于废弃茶叶渣表面制备了复合材料茶叶基水合氧化铁(HFO-TW),研究了HFO-TW对水溶液中Pb(Ⅱ)的吸附特性,探讨了溶液pH值、时间、共存碱土离子、温度、Pb(Ⅱ)初始浓度等因素对Pb(Ⅱ)的吸附效果的影响.结果表明酸性范围内,Pb(Ⅱ)的吸附量随溶液pH升高而增大;Pb(Ⅱ)的吸附速度较快,100 min内便可达吸附平衡,且动力学曲线较好地符合伪一级和伪二级动力学模型,拟合系数可达98.8%;在竞争离子Ca(Ⅱ)/Mg(Ⅱ)的浓度高于Pb(Ⅱ)50倍时,HFO-TW对Pb(Ⅱ)仍具有较强的吸附能力,Pb(Ⅱ)的吸附量仅分别下降12.1 mg·g-1和8.1 mg·g-1;Pb(Ⅱ)的吸附过程较好地符合Langmuir等温模型,理论最大吸附容量为89.43 mg·g-1,远高于未经改性的茶叶渣和其他生物吸附剂.所有结果均证实HFO-TW在净化实际铅污染水体中有着较为广阔的应用潜力.

Hydrated ferric oxide was successfully impregnated onto tea waste by precipitation to obtain a new sorbent named HFO-TW, the adsorption characteristics of which toward Pb(Ⅱ) in aqueous solution was investigated by evaluating the effects of pH value, contact time, coexisting ion, temperature, and initial concentration of Pb(Ⅱ) . The Pb(Ⅱ) sorption onto HFO-TW was pH-dependent, and the higher pH value was more helpful for Pb(Ⅱ) adsorption onto HFO-TW in the pH range of 2. 5-7. Lead sorption speed was quick and could reach equilibrium within 100 min, and the kinetics curve could be fitted well by both pseudo-first and pseudo-second models. The related coefficient was 98. 8%. HFO-TW exhibited highly selective lead retention and the adsorption capacity of Pb(Ⅱ) onto HFO-TW was declined by only 12. 1 mg·g -1 and 8. 1 mg·g-1 in the presence of competing Ca(Ⅱ) , Mg(Ⅱ) at 50 times of the target ion. In addition, Pb(Ⅱ) sorption onto HFO-TW could be described satisfactorily by Langmuir model, and the maximal sorption capacity calculated by Langmuir equation was 89. 43 mg·g-1 , which was much higher than the unmodified tea waste and other bio-sorbents. All the results validated that HFO-TW was a promising sorbent for removal of lead from waters.