Preparation and application of porous materials from coal gasification slag for wastewater treatment: A review

In recent years, coal gasification has been gradually promoted as clean technology, and coal gasification slag (CGS) emissions have increased accordingly. CGS, including coarse slag and fine slag, is rich in SiO2 and Al2O3 and has pozzolanic activity, and thus CGS can be regarded as a cheap source of aluminosilicate. Also, CGS, especially the fine slag, usually contains higher contents of residual carbon which has a large specific surface area and low volatility and hence can be considered as a favorable precursor of activated carbon. Benefiting from these characteristics, CGS can be used to prepare high value-added porous materials, such as zeolite, mesoporous silica, carbon-silicon composite, and porous ceramics, and the obtained structures accommodate both sufficient adsorption capacity and low cost. Here, we review the research advances in characteristics of CGS and preparation methods of CGS-based porous materials, as well as their adsorption performance of heavy metal ions, organic dyes, ammonia nitrogen, and other water pollutants. The current studies indicate that CGS-derived adsorbents are effective and economical alternatives for removing aqueous pollutants. In addition, further research prospects on CGS-based porous materials are proposed.