学术论文

      pH 值对天然磁铁矿吸附水中Pb2+的影响及吸附机制研究

      Adsorption mechanism of lead (Ⅱ)ions on natural magnetite from aqueous solution and effect of pH value

      摘要:
      以天然磁铁矿作为吸附材料,通过静态批式实验考查了pH 值对磁铁矿吸附 Pb2+的影响,并研究了该吸附剂对Pb2+的等温吸附动力学特性,同时利用XRF和 SEM对吸附前后的磁铁矿进行表征,探讨该吸附剂去除水中Pb2+的作用机制.研究结果表明,随着反应初始pH 值的增加,磁铁矿对 Pb2+的吸附作用不断增加,当pH 值=6时,其最大吸附率为97.80%.磁铁矿对水中 Pb2+的吸附热力学等温线符合 Lang-muir方程.当吸附剂粒径为120~150μm、用量20 g/L时,在温度30℃,pH 值=5,160 r/min 振荡30 min时其饱和吸附量达16.98 mg/g.磁铁矿对 Pb2+的吸附作用可以用准二级动力学模型Y=0.0986X+0.5435描述,其相关系数R2为0.992,吸附速率常数K2为0.018(g·mg-1)/min.研究结果还表明,磁铁矿所吸附的 Pb 以氧化态形式(PbO 和 Pb2 O3)存在,磁铁矿对 Pb2+的去除机制包括表面沉积、离子交换、物理吸附和化学吸附等综合作用的结果.
      Abstract:
      In the present investigation,the natural magnetite was employed in studies on the adsorption effects of pH during the removal of Pb(Ⅱ)ions from aqueous solutions by static batch experiments,and the adsorp-tion kinetics and isotherms were also studied.The magnetite was characterized by SEM and XRF before and af-ter sorption in order to analyze the mechanism on Pb2+ adsorption.The results demonstrated that it had a better efficiency on Pb2+ adsorption as the initial pH value increased and the adsorption rate was 97.8% while pH value was 6.When the conditions were magnetite particle size 120-150μm (100-120 mesh),magnetite initial concen-trations 20 g/L,pH value 5,temperature 30 ℃ and shaker rotational for 30 min at speed of 160 r/min,respec-tively,the saturated adsorption capacity was 16.98 mg/g.It was concluded that the Langmuir isotherm was more suitable to fit equilibrium adsorption data,and the adsorption kinetic data for Pb2+ onto magnetite parti-cles fitted by pseudo-second-order equations withY=0.0986X+0.5435 model,R2=0.9923 and K2=0.0179 (g ·mg-1 )/min.Furthermore,Pb2+ adsorbed onto the magnetite existed in PbO or Pb2 O3 .The removal mecha-nism of Pb2+by natural magnetite contains the coordinated actions of superficial deposit,ion exchange,physical adsorption and chemical adsorption.
      Author: JIANG Bin-hui LI Li ZHAO Yan FANG Ping MA Li HU Xiao-min
      作者单位: 东北大学 资源与土木工程学院,辽宁 沈阳,110004
      刊 名: 功能材料 ISTICEIPKU
      年,卷(期): 2013, (23)
      分类号: T31
      机标分类号: X75 X70
      在线出版日期: 2013年12月19日
      基金项目: 国家自然科学基金资助项目,水体污染控制与治理科技重大专项资助项目