Preparation and characterization of poly (lactic acid)/activated carbon composite bead via phase inversion method and its use as adsorbent for Rhodamine B in aqueous solution

The preparation of porous materials using biodegradable materials has attracted much attention in the field of environmental pollution control. A non-toxic, user-friendly and inexpensive adsorbent bead was prepared from poly (lactic acid) (PLA) and activated carbon (AC) using a phase inversion technique. The porous structure of the PLA/AC bead was characterized by scanning electron microscopy and nitrogen adsorption−desorption methods The removal of the carcinogenic dye Rhodamine B was studied by batch equilibration method and it was found that the monolayer maximum adsorption capacity was 149.57 mg g−1 at 60 °C, pH 4. A study of kinetics adsorption revealed that the Rhodamine B molecules diffused very rapidly into the interconnected pores of the PLA/AC 5% wt. beads and agreed very well with the intraparticle diffusion model. The negative value of Gibb's free energy indicated a spontaneous adsorption process, and the enthalpy change (23.92 kJ mol−1) implied an endothermic adsorption process. Desorption studies showed that the percentage of desorbed Rhodamine B solution increased with a decrease in pH. The results indicated that the PLA/AC bead will provide a new alternative granular adsorbent for the removal of pollutant cationic dyes from water.