定向插层组装联合微波能制备专性大容量钒吸附镁铝水滑石修复地下水钒污染研究

Vanadium in groundwater (in forms of vanadate and its condensation acid radical) is hard to remove. Previous studies show that Mg/Al-Layered Double Hydroxide (MA-LDH) has higher removal capacity than traditional adsorbents. However, the anions other than vanadate in groundwater may compete intercalation sites of MA-LDH with vanadate, and the structure of mental layers may break during the calcination removal of interlayer anions. In this study, external-electric field is applied under which the vanadate intercalated MA-LDH can grow on and vertically to the conductive metallic oxide bases, and the distance between two metal layers of MA-LDHs remains unchanged after the vanadate in between is removed. This synthetized MA-LDH can only absorb vanadate again for its intercalation anion when used as an adsorbent in ground water. For the difficulty of metal layer breaks during calcination, microwave was chosen as the heating source which has the function of inner homogeneous heating that can synchronously break down the chemical bonds of interlayer anions without damage the metal layers. For the issue of inconvenient practical usage of powdered LDHs, assembling package method is proposed to synthetize LDHs. The absorption material produced is in a form of macro plate, in which metallic oxide bases are loaded on the surface of a conductive quartz glass in the format of column array and each base is covered with high density LDHs. These plate formed absorbents can be easily used in the field groundwater remediation. In addition, it can be repetitively used after adsorption saturation by microwave calcination removal of vanadate.

地下水中的钒（钒酸根及缩合酸根）较难去除。相比传统吸附剂，镁铝水滑石的去除能力更强。然而，镁铝水滑石吸附钒时面临常规阴离子竞争插层位点、煅烧脱除层间阴离子时层板易损等困难。本项目提出外加电场诱导，在导电金属氧化物基底上定向生长钒酸根插层钒镁铝水滑石方法，并利用碳酸根交换钒酸根，煅烧后插层层板间距不变，只有地下水中的钒酸根能基于“记忆效应”重新进入插层，从而屏蔽竞争阴离子，实现专性吸附。针对煅烧造成水滑石层板破损问题，提出微波热源煅烧脱层技术，通过微波能激发内摩擦均匀受热，利用层板与插层间的微波热稳定性差异，使层间阴离子化学键同步断裂脱除并保持层板完整性，实现大容量吸附。针对水滑石分散粉末较难实用问题，提出集合式组装方法，金属氧化物负载于导电玻璃上形成基底柱阵列，其上密集生长水滑石，从而形成可循环再生的导电玻璃载基底柱阵列载水滑石的组装式板体，推动钒污染地下水修复技术的实用化。

针对金属钒的理化特性为五价钒[V(V)]的毒性大且迁移性强，纳米零价铁（nZVI）和微米零价铁（mZVI）应用于钒污染地下水时易团聚钝化、价格昂贵、不适于实际污染地下水的长期修复应用等关键科学问题，本项目提出通过改性修饰提高其对污染物的去除能力，研究改性材料在多孔介质中的迁移机制和修复效果的研究思路，为实际钒污染地下水原位反应带修复技术提供技术参数。结合纳米零价铁（nZVI）高活性，制备水滑石负载纳米零价铁材料（nZVI@LDH），探究零价铁对钒的去除机理，验证零价铁材料原位修复钒污染地下水的适用性。结合微米零价铁（mZVI）造价低更适用实际修复工程的特性，对mZVI改性，提高其对钒的去除能力和自身迁移性能，通过模拟柱实验模拟原位反应带修复技术，探究改性零价铁在含水介质中的迁移机制和除钒性能。结合原位反应带修复技术的要求，对S-mZVI进行黄原胶的稳定化，制备S-mZVI@XG，提高其在地下水中的迁移能力，以此制备兼具钒高效去除能力和优良迁移性能的零价铁改性材料。模拟原位反应带修复技术，研究S-mZVI@XG在多孔介质中的迁移机制和修复效果，为实际钒污染地下水原位反应带修复技术提供技术参数。