Botswana Institute for Technology Research and Innovation
Botswana
Problem Statement
The United Nations Environment Programme (UNEP, 2024) reported that 2.3 billion people are living in countries categorized as “water-stressed”. This water stress emanates from water scarcity or water being contaminated by toxic ions, drug metabolites, salinity, etc. The project seeks to develop water filtration materials (membranes) derived from biomass cellulose for use at household and community levels. The identified biomass are invasive plant species that are a menace to the environment, and elephant dung is waste from the high population of elephants found in Botswana, making cellulose a sustainable resource.
Progress Highlights
Cellulose was successfully extracted from elephant dung, honey mesquite, and sisal plants (invasive species) and characterized. It is currently being appropriately functionalized to impart metal ions, anions, quaternary ammonium compounds, and salinity removal abilities in preparation for membrane fabrication and testing.
Key Findings
Cellulose was chemically extracted from elephant dung, honey mesquite, and sisal leaf fibers. The amounts of cellulose extracted from honey mesquite and sisal leaf fibers were 37% and ≈50%, respectively. Elephant dung also furnished ≈50% cellulose. The results show that the 3 biomasses are good cellulose sources.
Potential Impact
Elephant dung, honey mesquite, and sisal leaf fibers are good sources of cellulose, which can be appropriately modified for various applications, replacing non-biodegradable synthetic polymer fibers. These biomasses are abundant and renewable, making them attractive as sustainable cellulose feedstocks. In our case, cellulose is used to develop materials for water filtration.
Summary
The presence of contaminants in several water sources in Africa makes water unpalatable and significantly reduces the amount of clean safe water available for human consumption. Dr Keroletswe’s research will develop methods of making filtration membranes that can be incorporated into water filters to enable households and/ or communities to clean contaminated water for themselves thereby increasing their access to clean safe water.
Grantee Description
Dr Keroletswe is an ARISE fellow and a Researcher at Nanomaterials Division, Department of Natural Resources and Materials at Botswana Institute for Technology Research and Innovation (BITRI) in Botswana. Dr Ngonye graduated in 2015 from the University of Botswana with a Ph.D. in Chemistry. Her Ph.D. research focussed on extraction of secondary metabolites from medicinal plants, their bioactivity studies and synthesis of heterocycles with antimicrobial activities.
Dr Keroletswe’s research interests include among others tapping into indigenous knowledge systems to inform research in chemistry of medicinal plants and membrane technology where she develops protocols for making sustainable filtration membranes from natural polymers as well as chemical modification of polymers for application in water filtration. This is driven by her desire to improve human lives through science, impart knowledge onto young scientists, inspire female African children by demonstrating that a girl/woman is capable and to contribute to advancement of technology in Africa.
Project: Sustainable Water Filtration Using Cellulose Based Membranes Derived From Local Biomass.
The project that Dr Keroletswe is researching on is focussed onto developing cellulose based water filtration membranes derived from abundant local biomass such as plants and animal excreta. The challenge with the current synthetic polymer membranes is that they are not only unsustainable (because of their non-renewability), but they are expensive and their waste cause environmental havoc that has adverse effect on natural ecosystems. Also, it has been difficult to upscale most of the membranes for treatment of large bodies of water for use by large communities. The protocols that Dr Keroletswe is developing will open a doorway for further research into the use of cellulose to other applications besides water filtration. Cellulose materials are viewed as the future of materials science. Thus, changing the size of cellulose from micron to nanoscale usher in attractive properties such as enhanced absorbent properties, high tensile strength, and elastic modulus, tuneable and gas impermeable of which may be of interest in other applications. Ngonye will chemically modify the extracted cellulose to target different water contaminants like toxic ions and salinity among others.
