Material Recovery from Energy Production & Storage Technologies and Water Contaminant Monitoring
Loading...
Authors
Tembo, Prichard M.
Issue Date
2024
Type
Dissertation
Language
en_US
Keywords
Leaching , Lithium-Ion Batteries , Photovoltaics , Recycling , Sensing
Alternative Title
Abstract
Global electrification and global warming have greatly influenced the investigation of alternative power generation options. Several of these are intermittent and/or require some form of energy storage. Solar technologies are one of the leading renewable energy generation options, with silicon photovoltaics (Si PVs) having the largest market share. PVs heavily rely on energy storage as they are dependent on the time of day and general weather conditions, and lithium-ion battery (LIB) technologies are amongst the frontrunner energy storage options. Several considerations have arisen around PVs and LIBs, notably, raw materials for manufacture and waste management at their end-of-life (EoL). These two concerns can be simultaneously addressed through the recycling of materials from waste PV modules and spent LIBs. Apart from treating solid waste, wastewater generation during operations is a major aspect of consideration. It is therefore essential to develop means for rapid water testing to monitor contaminant discharge levels. The main goals of this dissertation are to highlight the work carried out in investigating methods of recovering materials from spent LIBs and waste PV modules. This was achieved through the application of organic and inorganic agents that have never been applied for the treatment and recovery of materials in these domains. A systematic approach for LIB pretreatment followed by leaching studies was developed, thereby contributing to LIB material recovery. A key characteristic is the ability to utilize the highlighted inorganic acids, the hydrohalic acids in the absence of a reducing agent and achieve high metal (Co, Li, Mn and Ni) recoveries of ~90%. Furthermore, based on conducted investigations, the inherent nature of the halide species presents aids in preventing toxic gas evolution. Recovery tests were carried out in which Si PV cells were recovered with minimal damage with the application of hexane as a solvent, presenting an eco-friendly and benign approach to pursue towards a strategic pathway for extending the life of recycled PV modules. Apart from material recovery, work on development of a sensor for water contaminant monitoring was explored, with cyanide as the working industrial contaminant monitored. Titanium dioxide (TiO2) nanotubes were used as the sensor substrate, with suitable and relatively inexpensive additives, achieving sensitive and selective electrochemical detection of cyanide in water. The current-time measurements indicated that i) increasing cyanide concentration could perturb the current proportionally, ii) the differential in the current could be used as a calibration for quantitative detection of cyanide, and iii) the developed sensor was highly selective even in the presence of interfering species. The work presented in this dissertation is expected to impact the materials recycling & recovery market by contributing towards providing more options for materials recovery, particularly regarding EoL LIBs and Si PV modules while also presenting a potential means for water contaminant monitoring during processing and recycling.