Experimental Study on Solidification of Pb2+ in Fly Ash-Based Geopolymers

Fang Liu,Ran Tang,Baomin Wang,Xiaosa Yuan

doi:10.3390/su132212621

Fang Liu, Ran Tang + Show 2 more

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https://doi.org/10.3390/su132212621

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Abstract

Fly ash from the incineration of domestic waste contains heavy metals, which is harmful to the environment. To reduce and prevent their contamination, heavy metal ions need to be sequestered. In this study, the geopolymer prepared by fly ash, a kind of power plant waste, is used to cure the heavy metal Pb2+, and to investigate the effect of different concentrations of Pb2+ on the compressive strength of the solidified body at different ages; the curing effect is judged by the toxic leaching concentration of heavy metals; the resistance of the solidified body to immersion is evaluated by comparing the change in strength before and after leaching; the fly ash-based geopolymer solidified body is compared with the cement solidified body in terms of curing effectiveness; the properties of the geopolymer and its mechanism of curing heavy metals are explored by microscopic tests. The results show that the fly ash-based geopolymer solidified body has good resistance to immersion; the optimum curing concentration of Pb2+ in fly ash-based geopolymers is 2.0%; compared to pure geopolymers, the strength of the solidified body at 28 d decreases by only 13.0%, and the leaching concentration of Pb2+ is 4.73 mg·L−1, which meets the specification requirements; the curing effect of the fly ash-based geopolymer is better than the cement solidified body; the microscopic test results indicate that the curing of Pb2+ by the fly ash-based geopolymer is a combination of both chemical bonding and physical fixation.

Highlights

IntroductionPublisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations
The compressive strength and its trends in the curing of Pb by the 30.63 fly ash-based geopolymer are shown in Table 5 and Figure 1
Compressive of fly ash-based cluded that the fly ash-based geopolymer solidified body has good resistance to soaking

Summary

Introduction

Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. With the development of society, the discharge of domestic waste increases rapidly. Proper disposal of these wastes has become an important task. There are three common methods: landfilling, composting, and incineration [1], of which incineration is becoming the main method because of its high efficiency, speed, significant volume reduction, and the possibility of converting waste into other energy sources; after waste incineration, most of the heavy metals such as Pb, Cr, and Zn will go into the fly ash that can cause irreversible damage to the environment and humans if handled improperly

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