In this study, the efficiency of activated carbon produced from Henna wood was studied to remove herbicide from aqueous solutions by adsorption. The parameters that affect the adsorption such as contact time, activated carbon dosage, initial concentration of adsorbate, stirring rate, temperature, and pH on bentazon adsorption were studied. The use of Henna wood as a raw material to produce activated carbon by physical activation was investigated. The activated carbons produced were characterized by nitrogen adsorption isotherms and point of zero charge properties. Brunauer, Emmett and Teller (BET) surface area of the activated carbon was determined. The removal of herbicide from aqueous solutions by adsorption on activated carbon produced was studied. The results of the present investigation showed that activated carbons prepared from Henna wood have good adsorption capacity for the removal of bentazon from aqueous solution. The Langmuir model provides the best correlation of the experimental equilibrium data. Adsorption isotherm according to BET classification was of Type I. The adsorption isotherms of bentazon revealed that adsorption increased as the concentration increases up to a saturation point. Enthalpy, entropy and free enthalpy adsorption have a negative value indicating that the adsorption of bentazon on the Henna wood activated was feasible, spontaneous and exothermic at 20 to 40°C.
Key words: Activated carbon, adsorption, thermodynamic parameters, Henna wood, Bentazon.
Abbreviations: b, Enthalpy of adsorption (L/mol); BET, Brunauer, Emmett and Teller; Ci, initial concentrations; Cf, final concentrations; EPA, environmental protection agency; FTIR, Fourier transfer infra-red; HPLC, high performance liquid chromatography; GAC, granular activated carbon; ΔG, free energy change; ΔH, enthalpy change; k1, pseudo 1st order rate constant; k2, pseudo 2nd order rate constant; LWAC, activated carbon prepared from Lawsonia inermis wood; Q, Langmuir adsorption capacity (mmol g-1); qe, the adsorption capacity (molg-1); qt, the amount of adsorbate adsorbed at time t (mol g−1); rpm, rounds per minute; ΔS, entropy change; SEM, scanning electron microscopy; V, volume of sample (mL); μg, micro gram; μL, micro-liter.
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