Elephant dung biochar (ED350) prepared by controlled heating at 350 ºC was used to
adsorb methylene blue (MB) in an aqueous solution. The effects of adsorption time, pH,
adsorbent dosage, and initial MB concentration were examined. Kinetic, isotherm, and thermodynamic models were then further analyzed to determine the adsorption. The results show
that ED350 was found to be efficient within 180 min. The optimum pH of MB adsorption
was 11. The Langmuir isotherm model was found to be the most suitable fit for the adsorption
equilibrium data, with ED350 having a homogeneous surface. The calculated equilibrium
parameter (RL) values were greater than zero and less than one, indicating a favorable
adsorption process and that ED350 was an efficient adsorbent for MB removal. The kinetics
of MB adsorption onto ED350 obeys the pseudo-second-order model. The results of thermodynamic data consideration reveal that the adsorption process is spontaneous and exothermic
in nature. This finding suggests that ED350 may prove to be an efficient low-cost adsorbent
of MB from wastewater.