Kinetics, thermodynamics, isotherm and regeneration analysis of chitosan modified pandan adsorbent

Abstract

There has been increased interest of chitosan as a dye adsorbent. Nonetheless, the chitosan tends to form bonding between their monomer chains that result in a rigid structure which affects its capability for adsorption. This is prime reason many recent studies modified chitosan through various modifications. However, most modifications involve chemical additive agents as well as complex procedures that are conducted under strong condition. Not much research consider low-cost organic materials as modifying agent. The purpose of this work is to investigate the performance of chitosan modified with pandan leaves in the adsorption of reactive black 5 (RB5). Modified chitosan-pandan (MCP) adsorbent was synthesized by simple wet impregnation under mild conditions. The MCP was characterized using Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and Brunauer-Emmett-Teller (BET) surface area analysis. Batch adsorption was conducted to study the effect of retention time (0–60 min), pH (3–11), initial dye concentration (100–1000 mg/L) and temperature (25–80 °C). Kinetics, isotherm, thermodynamics and regeneration evaluation were also performed on the adsorption data. The kinetics data obtained fitted well to the pseudo-second order model, indicating the role of chemisorption with the influence of intraparticle diffusion. For isotherm study, the data is best fitted to the Langmuir model (R2 = 0.91) with maximum adsorption of 169.49 mg/g. Thermodynamics analysis showed that the adsorption is feasible, endothermic and occurred spontaneously. MCP has been regenerated up to 5 times with percentage removal above 50% by washing with distilled water only. In conclusion, natural polyphenols from pandan leaves have been incorporated into chitosan to prepare high-efficiency adsorbent with satisfactory performance in RB5 removal from aqueous media. The MCP is a new promising biodegradable adsorbent for removal of dyes from textile wastewater.