Paranitrophenol and Methylene blue Adsorption from Synthetic Wastewater on Chemically Activated Carbon Derived from Lemongrass (Cymbopogonnardus)

Bethelhem Teklie
Department of Chemistry, College of Natural and Computational Science, Debre Berhan University, Debre Berhan, Ethiopia,

Amare Ayalew
Department of Chemistry, College of Natural and Computational Science, Debre Berhan University, Debre Berhan, Ethiopia,

Bizuayehu Tadesse
Department of Chemistry, College of Natural and Computational Science, Debre Berhan University, Debre Berhan, Ethiopia,

Abstract

The adsorbent (chemically activated carbon) was ready from Lemongrass (CymbopogonNardus) under chemical activation method. The characterization of chemically activated carbon was done with FT-IR, XRD, SEM techniques, Methylene blue number and pH zero point charge. The scanning electron microscopy image of the adsorbent showed the formation of a highly porous surface. The adsorbent has a high adsorption efficiency at low pH for Paranitrophenol (p-NP) due to cationic surface of adsorbent, whereas the adsorbent has a high adsorption efficiency at large pH for Methylene blue (MB) due to anionic surface of adsorbent results the electrostatic interaction of cationic charge of MB dye. Bach adsorption during optimization adsorption result of p-NP occurs at pH 2, contact time of 90 min, concentration of 10 mg/L and 0.4 g adsorbent dose, and optimum adsorption of MB occurs at pH 6, contact time of 90 min, concentration of 25 mg/L and 0.2 g of adsorbent dose. From isotherm models, adsorption process of p-NP and MB on to activated carbon followed Langmuir model than Freundlich for both adsorbates. The maximum Qo = 3.6 mg/g and 103 mg/g for p-NP and MB respectively was found as adsorption capacity result. The kinetics model revealed that pseudo second order is found to be well fitted which indicated that the adsorption mechanism more favors electrostatic interaction between both adsorbates and activated carbon (AC). Hence, Activated carbon was found to be the best adsorbing material on removal of p-NP and MB dye.

Keywords: Adsorption; Activated carbon; p-NP; Adsorption isotherm; kinetics; MB