Adsorption of Cu2+ to biomass ash and its modified product

Abstract

Ash produced by biomass power plants has great potential for the removal of heavy metal ions from aqueous solution. The pollution of toxic heavy metals to water is a worldwide environmental problem. Discharges containing copper, in particular, are strictly controlled because the excessive copper can cause serious harm to the environment and human health. This work aims to investigate the adsorption characteristics of copper ions in aqueous solution by biomass ash and the modified products, and to evaluate their potential application in water pollution control. The biomass ash was modified with a mesoporous siliceous material and functionalized with 3-aminopropyltriethoxysilane. The surface properties of the biomass ash and the newmatrixwere studied to evaluate their adsorption property for Cu2+ ions at different pHs, initialmetal concentrations and the thermodynamic and kineticwere studied. The chemical and morphological properties of this modified material are analyzed; the specific surface area of themodified biomass ashwas nine times that of the initial ash. Both of the two materials showed a strong affinity for Cu2+, and the Langmuirmodel could best represent the adsorption characteristics of Cu2+ on the two kinds ofmaterials. The adsorption capacity of copper on thematerial increased with the increase of pH and pH 6 was the optimum pH. Thermodynamic analysis results showed that the adsorption of Cu2+ was spontaneous and endothermic in nature. The adsorptions of Cu2+ onto the modified biomass ash followed pseudo-second-order kinetics.