Modelling and optimization of competitive bio-sorption of copper and lead ions using fruit peels

A thesis submitted in fulfilment of the academic requirements for the degree of Doctor of Engineering: Chemical Engineering, Durban University of Technology, 2022. ; The application of various agricultural-based materials as adsorbents for the removal of heavy metal ions from aqueous solutions has attracted the interest of many researchers. Many studies have been conducted on the removal of heavy metals from wastewater using the bio-sorption process with a focus on wastewater containing single solutes. In addition, the existing column adsorption models were developed to describe the dynamic behaviour of single solute biosorption processes. However, the application of a linear driving force model which makes use of batch experimental results to describe the bio-sorption process in a fixed-bed has not been reported for binary solute systems. In this study, the performance of orange and banana peels was investigated for the removal of copper and lead ions from wastewater in both single and binary systems. These bio-sorbents were used in their natural form. The characterization of the bio-sorbents before and after adsorption was achieved using analytical techniques. Fourier Transform Infrared Spectroscopy (FTIR) was used to determine the functional groups present on the surface of the bio-sorbents. The results showed that the bio-sorbents contain various functional groups such as carboxyl, hydroxyl, carbonyl, aminyl, and alkyl groups that enhanced the adsorption process. After adsorption, there were significant shifts in the peaks representing hydroxyl and carboxyl groups which were common to both biosorbents. Therefore, it was concluded that ion exchange is the sorption mechanism responsible for the adsorption of metal ions. The Scanning Electron Microscopy with Energy Dispersive X-ray Spectroscopy (SEM/EDS) was used to determine the morphological structure and the elemental composition of the bio-sorbents. The surfaces of the bio-sorbents showed an irregular, and microporous structure while the elemental ...