Observation of dissolution behavior of dredged sediment in NaOH-activated system to evaluate potential activity for precursor usage

Abstract

Understanding the dissolution mechanism of dredged sediment (DS) is of great importance for the usage of aluminosilicate precursor and sustainable utilization of solid waste. In this paper, a new method was proposed for evaluating the activity of a complicated system with multi-minerals. From the perspective of solid phases, the dissolution of DS detected by TESCAN Integrated Mineral Analyzer (TIMA) was characterized by the reduction of mineral phase area and element variation of individual phases. Meanwhile, the dissolved element in medium was monitored by Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES) from the aspect of solution. It was found that the dissolution of DS preferentially occurred at the locations with high surface energy and resulted in the reduction of phase area, and the area with low surface energy was also dissolved to a limited extent. Plagioclase and zeolite exhibit higher activity, and phyllosilicates are generally more reactive than framework silicates. The inconsistency between dissolved Al and Si from solid and those into solution reveal that the formation of initial geopolymer unit requires a higher consumption of Si than Al. This study opens up a new way of DS utilization and provides a theoretical basis for the development of a widely obtained and environmentally friendly precursor of geopolymer.