Activated carbon from H3PO4 -activated Moringa Stenopetale Seed Husk for removal of methylene blue: Optimization using the response surface method (RSM)

Abstract

In this study, an alternative precursor for production of activated carbon was introduced using Moringa Stenopetale Seed Husk (MSSH). Moreover, H 3 PO 4 was used as a chemical activator in the thermal carbonization process to convert MSSH into activated carbon. The prepared adsorbent was characterized using proximate analysis and Instrumental like FT-IR, SEM/EDX, and XRD. The optimization process was developed using the Box-Behnken methodology (BBM) and the response surface method (RSM). Analysis of variance (ANOVA) revealed a good agreement between experimental and predicted value. Investigation of the processing parameters was done using the batch adsorption method. The optimal conditions for removing methylene blue were found to be the initial dye concentration (316 mg/L), contact duration (19.3 min), adsorbent dosage (0.055 g), and shaking speed (176 rpm). Maximum efficacy was found to be 99.4%, and the highest adsorption capacity was 436.68 mg/g. The experimental results have been best fitted well by the Langmuir isotherm model with the higher correlation coefficients of R 2 = 0.954 rather than Freundlich and Temkin adsorption isotherm. This indicates that the process followed homogenous adsorption of adsorbate on the surface of adsorbent. The adsorption kinetics was best fitted with pseudo-second order kinetics. The result of thermodynamic parameters showed that a negative value of ΔG o and positive ΔH o confirms the spontaneous and endothermic nature of the adsorption of MB onto the adsorbents. The positive values of ΔS o indicate the increase in randomness of at the solid-liquid interface during the adsorption process. Generally, the results indicate that activated carbon prepared from MSSH can be used as a low cost, easily applicable and eco-friendly alternative adsorbent for treatment of effluents containing MB dye. • Activated Carbon was prepared form Moringa stenopetale seed husk. • The Activated carbon prepared was characterized by proximate value and analytical instruments. • The Response surface methodology (RSM) and Box-Behnken approach were used to create the optimization procedure. • Different Adsorption parameters and Adsorption models was Conducted. • The highest adsorption capacity was 436.68 mg/g, and maximum efficacy was found to be 99.4%