Abstract:
Biochar is widely utilized in low-cost water treatment. However, chemicals used in most of the recorded activation techniques are
corrosive, may cause secondary pollution, and not accessible by rural communities, reducing their value of being cost-effective. In this
study, Trema orientalis wood biochar (WB) was successfully activated with natural coconut vinegar employing a facile technique to produce
a green adsorbent for efficient aqueous methylene blue (MB) removal. Batch studies showed a three-fold higher MB adsorption capacity
of coconut vinegar treated wood biochar (CVWB) compared to WB. Percentage removal ranged between 98-79% at lower dye concentrations
(50-100 mg/L) and 79-48% at higher dye concentrations (100-300 mg/L). Isotherm data best fitted to the Freundlich model. Kinetic data
fitted to both pseudo second order and intraparticle diffusion models, suggesting that the adsorption was governed by a pore filling
mechanism with predominant electrostatic attractions, and the reaction rate was diffusion controlled. FTIR, XPS, and water contact
angle measurements confirmed increased surface oxygenated groups of CVWB. XPS showed a three-fold increase in O/C atomic ratio.
BET and AFM studies gave evidence to the increased porosity. Therefore, the enhanced MB adsorption capacity of CVWB was attributed
to both the increased surface oxygenated functional groups and porosity.
