DeMarco Matthew J, SenGupta Arup K, Greenleaf John E
Department of Civil and Environmental Engineering, Lehigh Univeristy, 13 E Packer Avenue, Bethlehem, PA 18015, USA.
Water Res. 2003 Jan;37(1):164-76. doi: 10.1016/s0043-1354(02)00238-5.
A fixed-bed sorption process can be very effective in removing trace concentrations of arsenic from contaminated groundwater provided: the sorbent is very selective toward both As(III) and As(V) species; the influent and treated water do not warrant any additional pre- or post- treatment; pH and composition of the raw water with respect to other electrolytes remain unchanged besides arsenic removal, and the sorbent is durable with excellent attrition resistance properties. In addition, the sorbent should be amenable to efficient regeneration for multiple reuse. This study reports the results of an extensive investigation pertaining to arsenic removal properties of a polymeric/inorganic hybrid sorbent. Each hybrid sorbent particle is essentially a spherical macroporous cation exchanger bead within which agglomerates of nanoscale hydrated Fe oxide (HFO) particles have been uniformly and irreversibly dispersed using a simple chemical-thermal treatment. The new sorbent, referred to as hybrid ion exchanger or HIX, combines excellent mechanical and hydraulic properties of spherical polymeric beads with selective As(III) and As(V) sorption properties of HFO nanoparticles at circum-neutral pH. Comparison of the results of fixed-bed column runs between the new sorbent and the polymeric anion exchanger confirmed that both As(V) and As(III) were removed very selectively with HIX. Equally important, no pH adjustment, pre- or post-treatment was warranted. Besides the absence of arsenic, the treated water composition was identical to that of influent water. HIX was amenable to efficient in situ regeneration with caustic soda and could subsequently be brought into service following a short rinse with carbon dioxide sparged water. During fixed-bed column runs, intraparticle diffusion was identified as the primary rate-limiting step for both As(III) and As(V) sorption. Repeated use of the same HIX particles during various laboratory investigations provided strong evidence that the new sorbent possesses excellent attrition resistance properties and retains its arsenic removal capacity over cycles.
如果满足以下条件，固定床吸附工艺在去除受污染地下水中的痕量砷方面可能非常有效：吸附剂对As(III)和As(V)物种具有很高的选择性；进水和处理后的水无需任何额外的预处理或后处理；除了去除砷之外，原水的pH值和其他电解质的组成保持不变，并且吸附剂耐用且具有出色的耐磨性能。此外，吸附剂应易于进行高效再生以多次重复使用。本研究报告了关于一种聚合物/无机混合吸附剂去除砷性能的广泛研究结果。每个混合吸附剂颗粒本质上是一个球形大孔阳离子交换树脂珠，通过简单的化学热处理，纳米级水合氧化铁（HFO）颗粒的团聚体已均匀且不可逆地分散在其中。这种新型吸附剂，称为混合离子交换剂或HIX，结合了球形聚合物珠的优异机械和水力性能以及HFO纳米颗粒在中性pH值下对As(III)和As(V)的选择性吸附性能。新吸附剂与聚合物阴离子交换剂之间固定床柱运行结果的比较证实，HIX对As(V)和As(III)都有非常高的选择性去除效果。同样重要的是，无需进行pH调节、预处理或后处理。除了不含砷之外，处理后的水成分与进水相同。HIX易于用苛性钠进行高效原位再生，随后用二氧化碳鼓泡水进行短时间冲洗后即可重新投入使用。在固定床柱运行过程中，颗粒内扩散被确定为As(III)和As(V)吸附的主要限速步骤。在各种实验室研究中对相同的HIX颗粒进行重复使用，提供了有力证据，证明这种新型吸附剂具有出色的耐磨性能，并在多个循环中保持其砷去除能力。
