Engineered microwave biochar from sago bark waste for heavy metals adsorption

Abstract

Microwave pyrolysis is an energy, time, and cost-saving process for conversion of biowaste from agricultural sector into biochar. Sago bark waste was microwave pyrolyzed at 400 °C to produce sago bark microwave biochar (M−B), which was then treated with NaOH and HCl to generate acid-base modified sago bark microwave biochar (M−Bab). FTIR analysis evidenced the changes in functional groups in M−B and M−Bab. SEM analysis found that microwave pyrolysis resulted in the formation of open structures and pores on the M−B and acid-base modification increased the porous structure in M−Bab. BET surface area increased from 29.547 m2/g of (M−B) to 119.040 m2/g of (M−Bab) after acid-base modification. M−Bab demonstrated higher removal at low initial heavy metal concentrations in batch experiments. Best model to illustrate Cr (III), Ni (II), and Pb (II) adsorption by M−Bab best represented by Freundlich isotherm, while Cu (II) adsorption by Temkin isotherms. Conversion of sago bark waste to M−Bab is a potential solution for both water pollution remediation and the issue of sago bark waste overabundance.