脱水铝污泥对水溶液中磷的吸附作用研究

ADSORPTION OF PHOSPHORUS IN AQUEOUS SOLUTION BY DEWATERED ALUM SLUDGE

研究了脱水铝污泥对水中磷的等温吸附特征和动力学过程,考察了3个因素对脱水铝污泥吸附磷的影响。结果表明,脱水铝污泥的等温吸附特征符合Langmuir和Freundlich方程,其中Langmuir方程描述更为准确,其最大饱和吸附量为11.1 mg.g-1。脱水铝污泥对磷的吸附作用受脱水铝污泥粒径和初始溶液含量影响较大,受温度影响不大:粒径由小于0.25 mm增大到1.0～2.0 mm时,吸附量由1.847 mg.g-1降低为1.045 mg.g-1;初始磷的质量浓度由5增加到15 mg.L-1时,吸附量由0.857 5 mg.g-1增加到2.396 mg.g-1;25、30、35℃温度下,吸附量分别是1.807、1.854、1.847 mg.g-1。脱水铝污泥吸附除磷的动力学过程符合准2级动力学模型,相关系数均大于0.95;由模型得出的脱水铝污泥对磷的平衡吸附量与试验所得平衡吸附量偏差范围为4%～16%。

The feasibility of using dewatered alum sludge as absorbent for the removal of phosphorus was studied. Phosphorus adsorption isotherm and its kinetics were examined and effect of adsorbent particle size, initial phosphorus concentration and temperature was investigated. The result showed that the date of phosphorus adsorption onto dewatered alum sludge are found to fit both Langmuir isotherm and Freundlicb isotherm well, however, the Langmuir isotherm yields a better fit than the Freundlich isotherm while its saturation adsorption capacity is 11.1 mg·g^-1. The adsorption was influenced by particle size and initial phosphorus concentration but slightly affected by temperature. The capacity of phosphorus adsorption reduced from 1.847 mg·g^-1 to 1.045 mg·g ^-1 when the adsorbent particle size changes from smaller than 0.25 rnm to 1.0-2.0 mm, while the capacity of phosphorus increases from 0.857 6 mg·g^-1 when the initial phosphorus concentration is 5 mg·g^-1 to 2.396 mg·g^-1 when the initial phosphorus concentration is 15 mg·L^-1. Moreover, when temperature was 25, 30, 35 ℃, the capacity of phosphorus adsorption was 1.807, 1.854, 1.847 g·L^-1 respectively. The change of phosphorus concentration with time can be described by the pseudo second-order kinetics with correlation coefficient of 0.95. Accordingly, amounts of phosphorus adsorbed at equilibrium can be calculated with error in the range of 4%- 16%.