Enhancing rubber (Hevea brasiliensis) seed shell biochar through acid-base modification for effective phenol removal from aqueous environments

Abstract

This work encompasses using acid-base modified rubber seed shell biochar (RSSB) as an adsorption approach to eradicate phenol from aqueous mediums. Potassium hydroxide (KOH) was used pre-pyrolysis to modify the RSS, and hydrochloric acid (HCl) was used post-pyrolysis to modify the RSSB. The methodology was divided into three stages: RSS pretreatment, RSS base-modification and pyrolysis, and RSSB acid-modification and processing. Temperature, pH and several other factors were investigated for their impacts on the adsorbent, and optimal conditions were established at pH 6, 1.0 g of rubber seed shell biochar (RSSB), 50 mg/L initial concentration, 120 min contact time, and 30 °C temperature. The highest phenol removal efficiency was recorded at 97.21 % using the RSSB-700 adsorbent. Thermodynamic, kinetic and isotherm studies were carried out on the adsorbents using the non-linear modelling approach. The pseudo-second-order kinetic model was declared optimal because the adsorption rate closely followed it, with minimal difference between the experimental and computed values. The maximum RSSB adsorption capacity is 13.32 mg/g, according to the equilibrium results, which follow the Langmuir isotherm equation. Thus, the aim of this research and all documented objectives have been fulfilled.

Keywords

• Adsorption
• Phenol
• Isotherm
• Kinetic
• Rubber seed shell