Adsorption of methylene blue from aqueous solutions using activated carbon derived from sand box seed shell (Hura crepitans): Isothermal, thermodynamic, and kinetic studies
Alozie U.H. Mba C.B. Sunday M.C. Onwuka U.F. King L.J. Anukwonke M.C. Uzokwe O.G.
January 2026Springer International Publishing
Journal of King Saud University - Engineering Sciences
2026#38Issue 1
This study explores the use of activated carbon derived from sandbox seed shell (SSS) for the removal of methylene blue (MB⁺) from aqueous solutions. The SSS was impregnated individually with KOH and H₃PO₄ at 85% of the biomass weight using a 1:3 solution ratio to enhance porosity and surface functionality. Carbonisation was performed at 700 °C under nitrogen following a 24-h soaking period. Characterisation using SEM, FTIR, EDS, BET, XRD, TGA, XRF, and PZC verified notable chemical and structural changes. BET surface areas increased from 209.454 m2/g (RSSS) to 543.378 m2/g (SSS-KOHAC) and 433.493 m2/g (SSS-H₃PO₄AC), with corresponding iodine numbers of 482.334, 977.361, and 1142.37 mg/g, respectively. Batch adsorption experiments demonstrated that the removal efficiency of MB⁺ increased with rising pH and peaked near neutral values, consistent with PZC measurements of 6.9, 7.12, and 7.83 for SSS-KOHAC, SSS-H₃PO₄AC, and RSSS, respectively. Thermodynamic modelling indicated spontaneous adsorption for activated samples (ΔG° < 0), whereas RSSS exhibited non-spontaneous behaviour (ΔG° > 0) at elevated temperatures. SSS-H₃PO₄AC showed the highest adsorption energy and selectivity, attributed to phosphate-derived surface groups. Adsorption followed favourable isotherm and kinetic models, confirming the potential of chemically activated biomass as an efficient, low-cost adsorbent for dye removal in water treatment applications.
Activated carbon , Adsorption , Biomass , Methylene blue , Sandbox seed shell , Wastewater
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Department of Mechanical Engineering, School of Engineering Technology, Federal Polytechnic Nekede, Nekede, Imo State, Owerri, 460231, Nigeria
Department of Robotics Engineering, School of Engineering and Digital Sciences, Nazarbayev University, Kabanbay Batyr Avenue 53, Astana, 010000, Kazakhstan
Department of Mechanical and Aerospace Engineering, School of Engineering and Digital Sciences, Nazarbayev University, Kabanbay Batyr Avenue 53, Astana, 010000, Kazakhstan
Department of Mechanical Engineering, Faculty of Engineering, University of Nigeria, Nsukka Road, Ihe Nsukka, Enugu State, Nsukka, 410001, Nigeria
Department of Mechanical Engineering, School of Engineering and Engineering Technology, Federal University of Technology, Imo State, Owerri, 460114, Nigeria
Department of Biochemistry, College of Natural Sciences, Michael Okpara University of Agriculture, Umudike Rd, Abia State, Umudike, 440101, Nigeria
Department of Mechanical Engineering
Department of Robotics Engineering
Department of Mechanical and Aerospace Engineering
Department of Mechanical Engineering
Department of Mechanical Engineering
Department of Biochemistry
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