Novel removal of water-insoluble disperse dye onto a low-cost adsorbent prepared from tropical fruit waste

Abstract

The potential of tropical fruit waste (durio zibethinus husk, DZH) as a low-cost adsorbent for removal of disperse blue 60 (DB 60) from an aqueous medium was studied under various conditions such as effects of adsorbent surface modification, contact time, pH, and temperature. The removal percentage of DB 60 was enhanced by approximately a factor of six when using the DZH treated by mineral acid compared to the untreated DZH. The functional groups of DZH before and after acid treatment were analyzed by Fourier transform infrared spectroscopy to elucidate these results. The surface structure of the DZH before and after adsorption was analyzed by field emission scanning electron microscopy. Adsorption equilibrium isotherms and kinetics of the DZH were studied using Langmuir and Freundlich models, as well as pseudo-first-order, second-order kinetic and intraparticle diffusion equations. The Langmuir isotherm model agreed well with the experimental data with a maximum adsorption capacity (q _max) of 54.6 mg g⁻¹. The data followed the pseudo-second-order equation. Thermodynamic studies showed that the adsorption was endothermic and not spontaneous at low temperature, and was controlled by a chemisorption process. The results show that DZH could be used as a low-cost material to compare with activated carbon for the removal of disperses dyes from effluents.

Keywords:

• Adsorption
• Disperse blue dye
• Tropical fruit waste
• durio zibethinus
• Isotherm
• Kinetic

Acknowledgments

Our gratitude goes to Ministry of Higher Education Malaysia for their financial supports under the Fundamental Research Grant. We are also grateful to the Hitachi Scholarship Foundation and Professor Dr Goto Masahiro from Kyushu University, Japan for their supports.