【摘要】 以农业废弃物小麦秸杆为吸附材料,探讨了小麦秸杆对Pb2+、Cd2+的吸附特性,重点研究了吸附时间、离子浓度、溶液pH值等对小麦秸杆吸附Pb2+、Cd2+的影响.结果表明,溶液pH值对吸附的影响大,在pH 2.0～6.0范围内,吸附量随溶液初始pH值的升高而升高.小麦秸杆吸附Pb2+、Cd2+的速度快,吸附动力学过程可以用准二级动力学方程进行描述.金属离子初始浓度在0.01～2.0 mmol.L-1范围时,Langmuir方程可以很好地描述Pb2+、Cd2+的等温吸附行为,拟合得到的理论饱和吸附量分别为0.15 mmol.g-1和0.11 mmol.g-1.小麦秸杆经NaOH水解处理后,对Pb2+、Cd2+的饱和吸附量分别增加至0.31mmol.g-1和0.22 mmol.g-1,为未处理时的2倍左右.而经酯化处理后,对Pb2+、Cd2+的饱和吸附量减小,分别减小至0.08mmol.g-1和0.06 mmol.g-1.红外光谱显示,小麦秸杆经酯化处理后,其表面具有金属离子吸附活性的羧酸根含量减少,而经NaOH处理后,羧酸根的含量增加,羧酸根在小麦秸杆结合金属离子的过程中起着重要作用.更多还原

【Abstract】 Wheat straw was used as biosorbent for lead and cadmium removal from aqueous solution.Especially,the effect of solution pH,contact time and ions concentration on the sorption process was intensively discussed.Result indicated that the metal removal was strongly dependent on solution pH and the sorption capacity increased with the increasing of solution pH in the pH range of 2.0-6.0.The sorption kinetic process fit well with the pseudo-second-order.Langmuir isotherm equation was used to evaluate the sorption capacity of the biomass.The qmax values for Pb2+ and Cd2+ were 0.15 mmol·g-1and 0.11 mmol·g-1 respectively.After NaOH hydrolated,wheat straw showed higher sorption capacity both for Pb2+ and Cd2+,qmax values for Pb2+ and Cd2+ reached 0.31 and 0.22 mmol·g-1 respectively.While the sorption capacity for Pb2+ and Cd2+ on esterified wheat straw decreased greatly.Fourier transform infrared spectroscopy(FTIR) analysis showed that carboxylic groups on the biomass play an important role in Pb2+ and Cd2+ sorption process.更多还原