High surface area acid-treated biochar from pomegranate husk for 2,4-dichlorophenol adsorption from aqueous solution

Abstract

In the present study, zinc chloride (ZnCl₂) followed by acid treating was employed for the fabrication of activated biochar from pomegranate husk (APHBC) for 2,4-dichlorophenol (2,4-DCP) adsorption from an aqueous solution. The batch adsorption experiments were carried out as a function of solution pH, APHBC dose, initial 2,4-DCP concentration, contact time, and ionic strength. The APHBC showed a well-developed pore with specific surface areas of 1576 m²/g due to explosive characteristics of ZnCl₂. In addition, the XRD analysis showed that the diffraction peaks between 15 and 35° corresponded to amorphous carbon. The pore size distribution results showed that APHBC was dominantly mesoporous materials. The pH_pzc value of APHBC was 6.15 ± 0.15. According to batch experiments, the optimum adsorption conditions were pH of 3.0, contact time 60 min, APHBC dose of 1.75 g/L and without ionic strengths. The absorption capacity of 2,4-DCP at the initial concentration of 150.0 mg/L promptly decreased from 259.5 ± 12.9 to 74.5 ± 3.7 mg/g as the APHBC dose increased from 0.50 to 2.00 g/L. The isotherm and kinetics study of 2,4-DCP adsorption by APHBC revealed that Liu and Avrami fractional-order well fitted with experimental data, respectively.

Keywords: Adsorption; Bio-based carbon; Biochar; Chemical activation; Pomegranate husk.