Diisobutylamine mediated CO2 mineralization and CaCO3 production from municipal solid waste incineration fly ash as raw ingredient and regeneration reagent

Abstract

The CO2 mineralization technology involving Ca leaching and subsequent mineralization has emerged in recent years. It is still plagued by slow mineralization rate and frequent pH swings, requiring the consumption of exogenous substances. In this study, a leaching-mineralization-regeneration process for CO2 sequestration and CaCO3 production from municipal solid waste incineration fly ash (MSWIFA) mediated by diisobutylamine was proposed. Ca could be effectively extracted into the leaching solution with a concentration of 37420 mg/L from fly ash while heavy metals could be left in the leached residue. Diisobutylamine, acted as an H+ extractant and a crystal form regulator, was mixed with 1-octnaol to form a novel extraction system. When diisobutylamine/1-octanol/leaching solution ratio was at 1:2:3, almost full precipitation of Ca and a high CaCO3 yield of 282.4 g/kgfly ash was achieved. The crystal form of the CaCO3 product was confirmed by scanning electron microscope to be spherical and identified by X-ray diffraction as vaterite. The product purity (99.1 %) met the standard requirement (HG/T 2226–2019) for industrial use. Fly ash acted as a regenerant and was able to fully regenerate the extraction system. The mineralization performance of the regenerated extraction system remained relatively stable in multiple cycles of mineralization-regeneration process. Given the fundamental nature of this research, it would provide a potential route for future CO2 mineralization and Ca-containing waste utilization.