Adsorption kinetics, isotherm and reusability studies for the removal of cationic dye from aqueous medium using arginine modified activated carbon

In the present work, we have successfully developed 2-amino-5-guanidinopentanoic acid modified activated car- bon (AGDPA@AC) for the effective removal of methylene blue (MB) dye from aqueous medium. The AGDPA@AC was characterized using different instrumental techniques viz., SEM, EDX, FTIR, TGA and zeta potential. The influ- ence of different parameters viz. pH, initial MB concentration, contact time and temperature on the adsorption capacity was investigated. The maximum adsorption capacity of MB of on AGDPA@AC was found at pH 8 and 120 min. The maximum Langmuir adsorption capacity of AGDPA@AC was 219.9 mg/g at 25 °C. The adsorption followed Langmuir isotherm and pseudo-second order kinetic models well. The result of thermodynamic data showed that the adsorption was spontaneous and exothermic in nature. The binding of MB dye onto AGDPA@ AC surface was through electrostatic interactions. Regeneration studies indicated that the adsorbent could suc- cessfully retain MB, even after four cycles. The adsorption percent of AGDPA@AC for MB dye was 75% even after four adsorption-desorption cycles.