利用天然浓缩丹宁合成新型凝胶吸附剂通过表面沉淀去除水溶液中铅

来源 :中国化学工程学报 | 被引量 : 0次 | 上传用户:long520liang
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Lead has caused serious environmental pollution due to its toxicity, accumulation in food chains andpersistence in nature. In this paper, removal of lead from aqueous solutions is investigated using a novel geladsorbent synthesized from natural condensed tannin. The novel adsorbent performs in aqueous solutions as a weakbase with valid basic groups of 1.2 mmol.g-1 tannin gel particles and therefore results in the elevation of pH valueof aqueous solutions. Even when initial pH is 3.6, final pH at equilibrium can climb up to 6.5 that is above the pHvalue for Pb(OH)2 precipitation formation and then lead can be removed from wastewater by this so-called surfaceprecipitation. The adsorption isotherm can be expressed by the Langmuir equation and the maximum capacity foradsorption of Pb is up to 92mg.g-1(based on dry adsorbent) when initial pH value is 3.6. Hence, the adsorbentdoes offer favorable properties in lead removal with respect to its high adsorption capacity at low initial pH value,which is advantageous to lead removal from acidic wastewater. A model is put forward to describe the individualadsorption phenomenon of the tannin gel adsorbent.
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