采用热化学改性法分别在30℃和65℃下制备了聚乙烯亚胺(PEI)改性荔枝果皮(MLP30和MLP65),用于去除废水中的Cr(Ⅵ)。结果表明,PEI上的胺基和亚胺基通过与果皮含氧官能团反应成功接枝到天然荔枝果皮吸附剂(LP)表面,增强了对废水中Cr(Ⅵ)的吸附能力。MLP对Cr(Ⅵ)的吸附符合Elovich动力学和Langmuir吸附等温模型,pH为4.0时,MLP30和MLP65对Cr(Ⅵ)的理论吸附容量分别为122.95mg/g和156.82mg/g,相较于LP(66.41mg/g)分别提高了85.1%和136.1%。MLP吸附Cr(Ⅵ)的主要机理包括静电吸引相互作用、氧化还原和表面络合。在酸性和弱酸性条件下MLP65都能有效去除水中的Cr(Ⅵ),且循环利用性能良好,是一种具有潜在利用价值的生物质吸附剂。研究结果可为废弃荔枝果皮的资源化与Cr(Ⅵ)污染控制提供理论依据和技术参考。
Polyethylenimine (PEI) modified lychee pericarp (MLP30 and MLP65) were prepared by thermochemical modification method at 30℃ and 65℃,then used to remove Cr(Ⅵ) from wastewater.The Cr(Ⅵ) adsorption capacity was enhanced due to the amines and imines on PEI successfully grafted to the surface of LP by reacting with the oxygen-containing functional groups.The adsorption of Cr(Ⅵ) by MLP30 and MLP65 agreed well with Elovich kinetic model and Langmuir isotherm model.The theoretical adsorption capacity of MLP30 and MLP65 for Cr(Ⅵ) was 122.95mg/g and 156.82mg/g respectively which increased by 85.1% and 136.1% when compared to LP (66.41mg/g) at pH 4.0.The mechanisms of Cr(Ⅵ) adsorption mainly included electrostatic attraction,oxidation-reduction reaction and surface complexation.MLP65 had good adsorption capacity under acidic and weak acidic conditions and good recycling performance,so it could be regarded an adsorbent with great potential utilization value.The research can provide theoretical foundation and technical reference for the resource utilization of pericarp waste and Cr(Ⅵ) pollution control in wastewater.
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基金资助
国家自然科学基金(41977114);广东省基础与应用基础研究基金(2020A1515011113);广州市科技计划项目(202002030455)
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