4种秸秆类农业废弃物对废水中Pb^(2+)去除效率

Removal Efficiency of Pb^(2+) from Wastewater by Four Straw-based Agricultural Wastes

为研究西红柿秆、草莓秆、胡豆秆和豌豆秆对废水中Pb2+的吸附性能和最佳去除条件,采用静态吸附实验考察了吸附剂投加量、pH、反应时间和初始Pb2+浓度对其吸附Pb2+性能的影响。研究其吸附动力学特性并对材料表面性质进行表征,同时讨论了其对金属制品加工厂所产生实际废水中Pb2+吸附能力。结果表明,Pb2+吸附量随投加量的增加而减少;在pH为3.54.0时,Pb2+吸附量较高,其中西红柿秆的吸附量最大达26.72 mg/g;在25℃,pH 4.0时,4种材料能在90 min内达到吸附平衡,准二级动力学模型(R2:0.8260.939)较准一级动力学模型(R2:0.5590.897)更符合其去除过程。Langmuir模型能较好地描述4种材料对Pb2+的等温吸附过程,表明它们对溶液中Pb2+的吸附以单层吸附为主。扫描电子显微镜-能谱仪和傅里叶变换红外光谱观察表明,材料表面具有丰富的羧基、羟基和氨基等官能团,有利于Pb2+的吸附。这4种材料是具有前景的处理Pb2+污染废水的吸附剂。

Batch experiments were carried out to study the removal properties and the optimum adsorption conditions of Pb2+from aqueous solution by the straw-based agricultural wastes(SAWs)including tomato stalk,strawberry stalk,broad bean stalk,and pea stalk,and the effects of influencing factors such as adsorbent dose,pH,reaction time,and initial concentration on Pb2+adsorption were investigated.Materials were characterized by Scanning Electron Microscope equipped with Energy Dispersive Spectrometer(SEM-EDS)and Fourier Infrared Spectrometer(FTIR).Simultaneously,the adsorption capacity of Pb2+in the actual metal product processing plants wastewater is discussed.The results showed that with an increase in the dosage,the Pb2+adsorption capacities decreased.The Pb2+adsorption on SAWs was strongly influenced by the pH of the solution.At pH 3.54.0,the adsorption of Pb2+was higher.The maximum adsorption capacities of tomato stalk were26.72 mg/g.Under 25℃and pH 4.0,the Pb2+adsorption by the SAWs could reach equilibrium within 90 min.The pseudosecond-order kinetic model(R2:0.8260.939)was more consistent with their removal process than that of the pseudo-firstorder kinetic model(R2:0.5590.897).The isothermal adsorption of Pb2+on SAWs could be well fitted with the Langmuir isotherm adsorption model,which suggested that the adsorption of Pb2+from solution by SAWs was mainly monolayer adsorption.SEM-EDS and FTIR indicated that these SAWs have rich functional groups such as carboxyl,hydroxyl,and amino groups on the surface,which is conducive to the adsorption of Pb2+.Therefore,they might be promising materials for the treatment of Pb2+polluted wastewater.