四种有机物料对Pb2+的吸附特性

为研究不同有机物料的性质特征以及对重金属离子的吸附能力,选用四种农林废弃物或其加工产物(锯末生物炭、玉米秸秆、鸡粪、食用菌菌渣),利用SEM、FTIR等方法对其形态和官能团进行表征,并通过对Pb~(2+)的批量吸附试验,考察了pH、时间、溶液初始浓度对吸附量的影响。结果表明,四种材料均能够有效吸附Pb~(2+),但吸附特性有一定差异。生物炭、秸秆、鸡粪最佳pH为5,且受pH影响较大;菌渣最佳pH为2,受pH影响不大。25℃、pH 5时四种材料均能较快地达到吸附平衡,且吸附量随时间的变化数据均符合准二级动力学模型,吸附量随初始浓度的变化数据均能较好地拟合Langmuir等温方程,其中生物炭的饱和吸附量远高于其他三种材料,达到411.52 mg·g~(-1),秸秆、鸡粪、菌渣的饱和吸附量分别为40.90、41.82、115.65 mg·g~(-1)。

Adsorption of Pb2+ by different organic materials in aqueous solution

Lead(Pb)is a common pollutant in water and soil, and organic materials have the potential to adsorb heavy metals.The properties and Pb2+absorption capacity of four kinds of agricultural and forestry wastes or processed products there of(sawdust biochar, corn stalks, chicken manure, and mushroom cultivation residue)were studied. The morphology and functional groups of these materials were character-ized using SEM and FTIR methods. Batch adsorption experiments were conducted to investigate the effects of pH, time, and initial Pb2+con-centration on the Pb2+adsorption capacity, and the adsorption kinetics and efficiency were studied by using different kinetic models, as well as Langmuir and Freundlich models, to fit the experimental data. All four organic materials effectively adsorbed Pb2+, but their adsorption properties differed. The adsorption capacity of straw, chicken manure, and biochar was dramatically influenced by pH value, with an opti-mum pH of 5.0. The optimum pH for mushroom cultivation residue was 2.0, and pH value had a weaker effect on its Pb2+adsorption capaci-ty, as the adsorption capacity decreased smoothly as pH increased. At 25℃and pH 5.0, all four materials quickly reached adsorption equi-librium, and the adsorption process could be well fitted by the pseudo-second-order kinetic model and Langmuir isotherm equation;the e-quilibrium adsorption capacity of biochar, at 411.52 mg·g-1, was much higher than that of the other materials. The maximum adsorption ca-pacity of straw, chicken manure, and mushroom cultivation residue was 40.90, 41.82, 115.65 mg·g-1, respectively.