Dipartimento d'Ingegneria dei Materiali e della Produzione, Università Federico II, Piazzale V. Tecchio 80, 80125 Naples, Italy.
J Environ Manage. 2011 Jul;92(7):1821-7. doi: 10.1016/j.jenvman.2011.03.012. Epub 2011 Apr 1.
This work presents an unconventional procedure for the recovery of spent Al-rich caustic soda solutions from the pickling of dies for the production of aluminium extrusions. Caustic soda was regenerated at roughly 70%, by precipitating aluminate, after addition of a silica source, in the form of zeolite A, a microporous material that is widely used in many technological sectors. It was shown that the process is reliable and can be repeated for several cycles, provided the concentration of the caustic soda solution is suitably restored. The by-product obtained, zeolite A, proved to be a high-grade material with performance as a cation exchanger and physical sorbent that is certainly comparable to that reported in literature (e.g., cation exchange capacity equal to 5.14 meq g(-1) vs. 5.48 meq g(-1) and water vapour adsorption capacity of 26.5% vs. 27.6% at 16 torr and 298 K). The economics of the process, although not examined yet, would appear generally favourable, considering that zeolite A is a valuable by-product which widely covers the costs for the recovery of the spent solutions. There are, therefore, significant prospects for the use of zeolite A, particularly as a builder in detergent formulation.
本工作提出了一种从铝挤压制品生产用模具的酸洗中回收富铝苛性碱溶液的非常规方法。在添加硅源沸石 A（一种广泛应用于许多技术领域的微孔材料）后，通过沉淀铝酸盐，苛性碱可在 70%左右得到再生。结果表明，该工艺可靠且可重复进行多次循环，只要适当恢复苛性碱溶液的浓度即可。所得副产物沸石 A 是一种高品质的材料，具有阳离子交换剂和物理吸附剂的性能，其性能与文献报道的相当（例如，在 16 托和 298 K 时，阳离子交换容量为 5.14 meq g(-1)，而水蒸汽吸附容量为 26.5% vs. 27.6%）。尽管尚未对该工艺的经济性进行研究，但考虑到沸石 A 是一种有价值的副产物，可广泛覆盖回收废溶液的成本，因此该工艺的经济性似乎总体上是有利的。因此，沸石 A 具有很大的应用前景，特别是作为洗涤剂配方中的助剂。
