Synthesis of Pervious Geopolymer from Coal Fly Ash and Bagasse Fly Ash for Copper Removal

Abstract

Geopolymer has recently gained popularity as an eco-friendly material because of its potential to valorize waste. It is a new class of inorganic material formed upon dissolution of aluminosilicate in the presence of an activating solution. The aluminosilicate minerals become reactive and then form into aluminosilicate oligomers. While most of the study in geopolymer research is focused on cement and concrete industry, it also gained attention as an alternative material for solving environmental pollution in water. This study thus explores the use of combining coal fly ash and bagasse fly ash as the aluminosilicate source to produce pervious geopolymer for the treatment of copper-contaminated water. While coal fly ash (CFA) is a by-product of a coal-fired power plant, bagasse fly ash (BFA) is a waste product of the co-generation plant of sugar mills from burning bagasse. These raw materials were mixed with coarse aggregates and activating solution composed of sodium hydroxide and sodium silicate to produce a pervious geopolymer. The effects of the mix proportions of CFA and BFA on the compressive strength, porosity, and permeability of pervious geopolymer were investigated. Moreover, the copper removal efficiency of pervious geopolymer was determined using atomic absorption spectroscopy (AAS). The findings revealed that pervious geopolymer is a promising material that could remove copper at 67–87% efficiency.