The removal of azo dyes is a critical issue in current textile industry wastewater treatment. In contemporary wastewater management, many structures that are in direct contact with wastewater are constructed with concrete. In this contribution, the removal of Congo red from aqueous solutions by the material in the surface of hardened binder paste was studied in multiple exposure experiments. Flat prisms made with ordinary Portland cement and ground granulated blast-furnace slag were stored in different aqueous solutions. The powdered surface material of these flat prisms was used as a substrate for the removal of Congo red from aqueous solutions. Storage in sodium sulfate solution lead to the formation of hydrotalcite nanosheets on the surfaces of hardened binder pastes rich in magnesium provided by the granulated blast-furnace slag. These nanosheets resulted in a large specific surface area and increased the discoloration capacity with respect to binder mass. The results also suggest that the carbonation of C-S-H can provide fresh calcite that can act as a secondary adsorbent. The results of this study suggest that cementitious binders with high magnesium contents could contribute to the removal of azo dyes from industrial wastewater by providing economically attractive treatment materials.

偶氮染料的去除是当前纺织工业废水处理中的关键问题。在当代废水管理中，许多与废水直接接触的结构都是用混凝土建造的。在这一贡献中，在多次曝光实验中研究了硬化粘合剂糊状物表面材料从水溶液中去除刚果红的方法。用普通波特兰水泥和磨碎的高炉矿渣制成的平面棱镜储存在不同的水溶液中。这些扁平棱柱的粉状表面材料用作从水溶液中去除刚果红的基质。在硫酸钠溶液中的储存导致在水滑石纳米片上形成了硬化的，富含镁的硬化的粘合剂糊状物，该糊状物是由粒状高炉矿渣提供的。这些纳米片导致大的比表面积并相对于粘合剂质量增加了变色能力。结果还表明，CSH的碳酸化可以提供新鲜的方解石，其可以用作辅助吸附剂。这项研究的结果表明，通过提供经济上有吸引力的处理材料，高镁含量的水泥基粘结剂可以有助于从工业废水中去除偶氮染料。