Date of Award

2018

Document Type

Thesis

Publisher

Edith Cowan University

Degree Name

Master of Engineering Science

School

School of Engineering

First Supervisor

Associate Professor Mehdi Khiadani

Second Supervisor

Associate Professor Guangzhi Sun

Third Supervisor

Professor Hongqi Sun

Abstract

Aqueous solutions are becoming increasingly contaminated in all parts of the world (2015). Heavy metals are toxic contaminants that are mainly distributed in urban stormwater run-off and industrial wastewaters as a result of some mining operations, electronic assembly planting, battery manufacturing, and etching operations (Kadirvelu et al. 2001). Pb (II) is a heavy metal that causes significant damage in the human body. Drinking lead-contaminated water even at low concentrations may cause lifethreatening conditions such as cancer, kidney damage, brain damage, and liver problems (El-Said 2010). Therefore, it is necessary to remove lead from aqueous solutions.

Several conventional physical, chemical, and biological systems have been used to eliminate Pb (II) ions from contaminated aqueous solutions, including membrane filtration (Song et al. 2011), electrolysis (Deng et al. 2010), chemical precipitation (Cort 2005), magnetic base methods (Ma et al. 2017), water filtration (Gohari et al. 2013, Magni et al. 2015), and adsorption techniques (Pehlivan et al. 2009). However, the cost of some of the cited techniques is prohibitively high, while others cannot remove low Pb (II) ion concentrations efficiently (Babel and Kurniawan 2003, Volesky and Holan 1995). Although adsorption is a reasonable process for removing dissolved lead from contaminated water, the cost of using conventional media (e.g. activated carbon and resin) make it cost inhibitive for the treatment of large quantities of wastewater (Cutillas-Barreiro et al. 2016, Demirbas 2008). It also takes a long time in some cases to achieve adsorption equilibrium (Czinkota et al. 2002).

In recent decades, interest in the use of cost-effective adsorbents to reduce the expense of water treatment processes has intensified. Attention has been focused on natural agricultural waste materials such as seeds (Gilbert et al. 2011), fruit peel (Mallampati et al. 2015), nut shells (Taşar et al. 2014) , crop residues (El-Said 2010), and fruit shells (Zein et al. 2010) as low-cost and environmentally friendly adsorbents which are highly efficient and generally available in large quantities (Ibrahim et al. 2010).

Against this backdrop, many agricultural residues are being produced every day, and they need to be managed. Using agricultural wastes to treat contaminated water is a low-cost and effective approach that deal with waste management and water treatment at the same time. This project describes an economically viable and practical way to utilize crop residues as adsorbents to remove toxic Pb (II) ions from lead-contaminated water. These agricultural waste adsorbents have a number of advantages; they are cheap and biodegradable, they have a porous surface, and are able to eliminate Pb (II) ions from contaminated water quickly and effectively.

Therefore, in this research two Western Australian crop residues were used as adsorbents to eliminate lead ions from aqueous solutions. The study was carried out in four phases: the first phase involved the selection and preparation of different local Western Australian agricultural wastes. Lupin straw and canola stalk were collected from local farms and studied for their efficiency as two low-cost natural adsorbents that can remove dissolved Pb2+ ions from synthetic wastewater.

In the second phase, experiments were carried out to understand the equilibria of Pb (II) adsorption onto adsorbents. The effect of various environmental conditions such as contact time, pH, initial adsorbent dosage and adsorbate concentration were investigated.

The presence of different functional groups, chemical compositions, and the surface characteristics of the adsorbents were analysed in the third phase using energy dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) devices. In the final phase, the obtained experimental data were validated using different isotherm models developed by Langmuir, Freundlich, Harkins-Jura, Redlich- Peterson and Halsey to describe the adsorption process based on the homogeneity of the surfaces of the adsorbents. Pseudo-first-order, pseudo-second-order, intra-particle diffusion, Elovich, and fractional power kinetic models were utilized to investigate the dynamic mechanism of lead adsorption onto adsorbents over time.

Access Note

Access to Chapters 5 and 6 and Appendix II of this thesis is not available.

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