Fungal bioleaching of WPCBs using Aspergillus niger: Observation, optimization and kinetics

Fariborz Faraji; Rabeeh Golmohammadzadeh; Fereshteh Rashchi; Navid Alimardani

doi:10.1016/j.jenvman.2018.04.043

Fungal bioleaching of WPCBs using Aspergillus niger: Observation, optimization and kinetics

J Environ Manage. 2018 Jul 1:217:775-787. doi: 10.1016/j.jenvman.2018.04.043. Epub 2018 Apr 24.

Authors

Fariborz Faraji¹, Rabeeh Golmohammadzadeh², Fereshteh Rashchi³, Navid Alimardani⁴

Affiliations

¹ School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran, Tehran, Iran.
² School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran, Tehran, Iran; Department of Chemical Engineering, Monash University, Clayton, Victoria 3800, Australia.
³ School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran, Tehran, Iran. Electronic address: rashchi@ut.ac.ir.
⁴ Department of Materials Engineering, Islamic Azad University, South Tehran Branch, Tehran, Iran.

PMID: 29660703
DOI: 10.1016/j.jenvman.2018.04.043

Abstract

In this study, Aspergillus niger (A. niger) as an environmentally friendly agent for fungal bioleaching of waste printed circuit boards (WPCBs) was employed. D-optimal response surface methodology (RSM) was utilized for optimization of the bioleaching parameters including bioleaching method (one step, two step and spent medium) and pulp densities (0.5 g L^-1 to 20 g L^-1) to maximize the recovery of Zn, Ni and Cu from WPCBs. According to the high performance liquid chromatography analysis, citric, oxalic, malic and gluconic acids were the most abundant organic acids produced by A.niger in 21 days experiments. Maximum recoveries of 98.57% of Zn, 43.95% of Ni and 64.03% of Cu were achieved based on acidolysis and complexolysis dissolution mechanisms of organic acids. Based on the kinetic studies, the rate controlling mechanism for Zn dissolution at one step approach was found to be diffusion through liquid film, while it was found to be mixed control for both two step and spent medium. Furthermore, rate of Cu dissolution which is controlled by diffusion in one step and two step approaches, detected to be controlled by chemical reaction at spent medium. It was shown that for Ni, the rate is controlled by chemical reaction for all the methods studied. Eventually, it was understood that A. niger is capable of leaching 100% of Zn, 80.39% of Ni and 85.88% of Cu in 30 days.

Keywords: Aspergillus niger; Bioleaching; Environmentally-friendly; Kinetics; Organic acids; WPCBs.

MeSH terms

Aspergillus niger*
Kinetics
Waste Management*
Water Purification