Tebogo Phetla Mashifana

University of Johannesburg | uj · Department of Chemical Engineering Technology

Environmental negotiations are complex, and conveying the interaction between science and policy in traditional teaching methods is challenging. To address this issue, innovative educational approaches like serious gaming and role-playing games have emerged. These methods allow students to actively explore the roles of different stakeholders in env...

Global water availability has been affected by a variety of factors, including climate change, water pollution, urbanization, and population growth. These issues have been particularly acute in many parts of the world, where access to clean water remains a significant challenge. In this context, preserving existing water bodies is a critical priori...

Enzymes have revolutionized conventional industrial catalysts as more efficient, eco-friendly, and sustainable substitutes that can be used in different biotechnological processes, food, and pharmaceutical industries. Yet, the enzymes from nature are engineered to make them adapt and enhance their durability in the industrial environment. One promi...

Acid-based geopolymers (ABG) have gained attention as eco-friendly alternatives to Ordinary Portland cement. This study synthesized ABG by activating fly ash with commercial H3PO4 and an alternative P leachate from sewage sludge. The ABG was synthesized at different molar concentrations of 4M, 6M, 8M, 10M, and 12M, while P-leachate geopolymer (PFA)...

High-grade copper ores have been depleted over the years, making it a challenge in the mining industry. This investigation focused on a methodology to recover iron (Fe) and copper (Cu) from a copper/nickel slag obtained from the Bamangwato Concession Limited (BCL) mine in Botswana. In this modified flotation approach, the Response Surface Methodolo...

Iron-laden tailings have received a lot of attention in recent years, especially for their potential use in civil engineering projects. Alkaline activation was studied as a method to use iron sludge from cable wire manufacturing industry (CWI). Two reagents, namely sodium silicate and sodium hydroxide concentrations of 1 M, 5 M, and 10 M were studi...

This review provides an overview of recent progress in the development of layered covalent organic frameworks (LCOFs) for the adsorption and degradation of pollutants in water and wastewater treatment. LCOFs have unique properties such as high surface area, porosity, and tunability, which make them attractive adsorbents and catalysts for water and...

This paper reports a synergic binding technique of dye and cadmium/lead ions onto freeze-dried modified chitosan beads (GCCS), in this work modified chitosan beads was applied in binary solution. Chitosan beads (CS) composite was produced and polyethyleneimine was grafted onto the backbone of the developed composite. The beads were analyzed utilizi...

The SARS-CoV-2 pandemic has resulted in the infection and death of many South Africans. This is in part due to a lack of testing facilities, equipment, and staff in many areas, particularly those with low population densities. The study focused on the infection dynamics of the virus in the Northern Cape province in all five municipalities investiga...

In line with the recent environmental concerns due to waste, researchers focus has been shifted to finding ways of recycling the waste in a most sustainable way. Accumulation of plastic waste, and rubber tyres in the environment is a concern and a threat to the environment. The current waste management has raised public awareness to look for new te...

The research investigated the chemical, mechanical and durability of composites developed from aluminum slag. Aluminum slag is a hazardous residue product of secondary Aluminum smelting. The objective of this research was to study the chemical and geotechnical properties of Al slag. To investigate the stabilization of Al slag with fly ash and GBFS...

The presence of heavy metal ions and emerging pollutants in water poses a great risk to various biological ecosystems as a result of their high toxicity. Consequently, devising efficient and environmentally friendly methods to decontaminate these waters is of high interest to many researchers around the world. Among the varied water treatment and d...

South Africa's production of wet flue gas desulfurization (WFGD) gypsum and fly ash (FA) has increased significantly owing to the country's dependence on coal power plant for electricity. These wastes are mainly dumped in landfills, which contributes to environmental pollution. Recycling WFGD gypsum to generate value-added products may benefit the...

The influx of emerging, prescribed, and FDA approved pharmaceutical contaminants (PCs) in the environment is continuously affecting human health and human cycle (even at trace amount) via contaminating water and aquatic life. Among them, non-degradable water-soluble residues which have been integrated with water streams and groundwater is a serious...

Copper slag is a hard material produced from smelting copper-bearing ores. Over the years, research has prioritized utilizing slag as a secondary source of base metals. This paper focuses on the grinding/milling of copper slag collected from the BCL Mine in Botswana to obtain a maximum amount of material in the desired size class with minimal energ...

Antibiotics, as pollutants of emerging concern, can enter marine environments, rivers, and lakes and endanger ecology and human health. The purpose of this study was to review the studies conducted on the presence of antibiotics in water, sediments, and organisms in aquatic environments (i.e., seas, rivers, and lakes). Most of the reviewed studies...

It is essential to develop a simple, applicable, and reliable assay to anticancer drug raloxifene (RAF) because of its significant usage and side effect due to entering residue in the environment. Fluorescence sensors developed and widely used because of them high selectivity, fast-response, and highly-sensitivity. The gold nanoparticles using chit...

Galvanized sludge (GS) generated from the cable wires manufacturing industry, waste foundry sand (WFS) from steel manufacturing and granulated blast furnace slag (GBFS), are the wastes that pollute the environment. This study investigated the use of these three materials to develop a value-added composite that can be utilized in the building and co...

Waste generation and management in industries is a major problem worldwide. In this study, granulated blast furnace slag (GBFS), fly ash (FA) + cement (CM), and de-silicated foundry sand (DFS) based geopolymers were developed and their leachability studied. The elemental composition showed that the raw materials studied had the highest compositions...

The accumulation of gold mine tailings (GMT) and polyethylene terephthalate plastic waste (PW) continue to impact the ecosystem negatively, and strategies are required to counteract these issues to maintain a sustainable environment. This study investigated the use of PW as a binder to mobilize heavy metals in GMT. Plastic was used as a binder to d...

The objective of this study was to synthesize a sustainable concrete material from readily available waste and by-products; Ground Granulated blast furnace slag (GGBFS) and waste foundry sand (WFS). GGBFS was alkali-activated using NaOH solution and used as a binder to completely replace Ordinary Portland cement (OPC). Concurrently, WFS was used as...

Copper slag is generated when copper and nickel ores are recovered from their parent ores using a pyrometallurgical process, and these ores usually contain other elements which include iron, cobalt, silica, and alumina. Slag is a major problem in the metallurgical industries as it is dumped into heaps which have accumulated into millions of tons ov...

In South Africa, coal represents the primary source of energy used for electricity generation. Coal power plants use the wet flue gas desulfurization (WFGD) process to remove sulfur dioxide (SO2) from their flue gas. However, this technology produces a large amount of synthetic gypsum, resulting in waste disposal and environmental pollution. This s...

Fly ash (FA) and granulated blast furnace slag (GBFS) are waste materials that are readily available. The purpose of this study was to develop a cementitious material (CM) through geopolymerization and utilize it with GBFS to stabilized FA to produce sustainable building material. The strength development of CM stabilized FA was studied over the cu...

Utilisation of industrial waste-based material to develop a novel binding material as an alternative to Ordinary Portland Cement (OPC) has attracted growing attention recently to reduce or eliminate the environmental footprint associated with OPC. This paper presents an experimental study on the synthesis and evaluation of alkali activated Ground g...

The mining industry generates large quantities of waste as tailings. The tailings have an adverse environmental impact. This study explored the utilization and stabilization of Barberton gold mine tailings (GMTs) and basic oxygen furnace slag (BOFS) to synthesize geopolymers for other applications. The geochemical, chemical, and geotechnical proper...

Gold tailings (GT) and slag disposed of in the landfill affect the environment. This study investigated the green process for the utilization of non-radioactive gold tailings and granulated blast furnace slag (GBFS) to synthesize a green and sustainable backfill material. The following mix design ratios of GBFS:GT were investigated; 100, 10:90, 20:...

Before disposal of any metallurgical waste to the environment, it is the responsibility of mining institutes to adhere to the permissible metal content limits. Base metals, especially iron and copper, have adverse effects of reducing the soil pH and excessive concentrations of these in the disposed waste may result in soil pollution and toxicity, w...

Waste phosphogypsum (PG) was treated with citric acid, oxalic acid, sodium carbonate and sodium bicarbonate to reduce the contaminants in the material and render the material applicable for other applications. The chemical composition revealed that the material was laden with contaminants such as fluorides and phosphorous which have a detrimental e...

This study was conducted to recover silica (desilication) as a valuable metalloid from waste foundry sand (WFS) by a leaching process and to find application for desilicated foundry sand (DFS). The leaching time applied was 5 h; 3 M of potassium hydroxide (KOH) was used as a leaching reagent. The agitation speed of 200 rpm and the liquid/solid rati...

This article investigated the feasibility to synthesise geopolymer bricks from Granulated Blast Furnace Slag (GBFS) using alkaline activators without addition of sodium silicate or silica reactive source. Sodium hydroxide (NaOH) is a typical alkaline solution used in geopolymerisation compared to KOH with addition of silicate solution used as a cat...

Gold mine tailings (GMT) generated from gold mining processes are readily available in South Africa. The generated GMT is disposed to the environment by land filling. This occupies considerable land area, which subsequently results into environmental pollution. Numerous industries use paper for a number of applications on daily basis and its genera...

Si and Al were leached from gold mine tailings (GMT) in order to determine if the GMT could be used as precursors for the synthesis of geopolymers. Possible synthesis of geopolymers from GMT would help reduce their potential pollution effects through heavy metal immobilisations. The effect of type of alkali (NaOH/KOH), alkali concentration, tempera...

Si and Al were leached from gold mine tailings (GMT) in order to determine if the GMT could be used as precursors for the synthesis of geopolymers. Possible synthesis of geopolymers from GMT would help reduce their potential pollution effects through heavy metal immobilisations. The effect of type of alkali (NaOH/KOH), alkali concentration, tempera...

The aim of this project was to develop a basic oxygen furnace slag (BOFS) and fly ash (FA) based geopolymer. The developed geopolymer were required to have strength to withstand hydraulic load. In respect to BOFS and FA, there are two main ways in which they can be handled following the best practices of conserving the environment. The two are disp...

The Voluminous quantity of phosphogypsum waste is generated by phosphoric acid manufacturing industry and end up being landfilled, resulting into environmental pollution. This study was done to determine applications for raw and treated waste phosphogypsum in building and construction, to determine the best conditions to produce the final product....

The objective of this study was to develop basic oxygen furnace slag (BOFS) blended with Fly Ash (FA) based masonry blocks that can be used in building and construction. The effect of variation of FA, potassium hydroxide (KOH) concentration, curing temperature, solid-liquid ratio on the Unconfined Compressive Strength (UCS) was investigated. The op...

The mining industry generates large quantities of waste as tailings. The tailings have an adverse environmental impact. This study explored the utilization and stabilization of Barberton gold mine tailings (GMTs) and basic oxygen furnace slag (BOFS) to synthesize geopolymers for other applications. The geochemical, chemical, and geotechnical proper...

Stabilization of gold mine tailings for application in the building and construction industry, provides a significant solution to the shortage of building and construction materials for the country’s growing population. The use of gold mine tailings in the production of building blocks / bricks, is examined in this study. The tailings used in the s...

Phosphogypsum (PG), a waste material readily available in large quantities, is generated in the wet process of phosphoric acid production. Due to the contaminants in the material and the radioactivity of PG, the use of this material has limitations. South African phosphogypsum (from Phalaborwa) contains high levels of thorium that could be recovere...

For over 200 years of gold mining, little has been done to minimize the negative impact of gold mine tailings to the environment. The overall generation of tailing by South African gold mining industry is approximately 300 million tons of slimes. This study was conducted to develop an effective chemical treatment process to reduce major heavy metal...

South Africa is a mineral-rich country with numerous metals and minerals such as gold, copper, and platinum group metals which are exploited to a significant extent. In this study the leaching of heavy metals from gold tailings was studied using sodium carbonate using gold tailings from Sibanye gold. The effect of the key leaching parameters were s...

Phosphogypsum is a by-product generated from phosphoric acid production processes. Due to the negative impact posed to the environment by the material, a chemical treatment process was developed to reduce the hazardous constituents in the material and render the final product useful for other applications. The treatment of phosphogypsum produced an...

A million tons of Phosphogypsum (PG) is stacked in the environment every year and is progressively considered an asset. South African construction industry is expanding as a result of infrastructural developments in the country, the reuse of PG in this industry is considered for recycling and reducing the stacks in landfills. Phosphogypsum is known...

This study investigated the use of a chemical treatment process to treat phosphogypsum waste generated from a phosphoric acid production plant and render the final product useful for building and construction applications. Four reagents namely; citric acid, oxalic acid, sodium carbonate and sodium bicarbonate were used for the reduction and removal...

The removal of contaminants from process effluent streams is very important, as the demand for water continue to increase. The contaminants in the effluent also pose an environmental pollution challenge and result in affecting human health. The objective of this study was to investigate the reduction of nickel in the presence of hydrazine (reducing...

This study investigated the removal of phosphorus from waste phosphogypsum by using citric acid as a leaching reagent, evaluated the potential environmental effect of the final product produced and provide recommendations for the application of developed products. A dissolution process was applied and three variables were studies namely, concentrat...

The use of industrial waste as a potential stabilizer of marginal construction materials is cost effective. Phosphogypsum and fly ash are industrial wastes generated in very large quantities and readily available in South Africa. In order to explore the potential stabilization of vastly abundant expansive soil using larger quantity phosphogypsum wa...

+e use of industrial waste as a potential stabilizer of marginal construction materials is cost effective. Phosphogypsum and fly ash are industrial wastes generated in very large quantities and readily available in South Africa. In order to explore the potential stabilization of vastly abundant expansive soil using larger quantity phosphogypsum was...

Residual deposits of Phosphogypsum are readily available in large quantities in South Africa and currently are landfilled or pumped into the sea, as there are limitations to engineering applications due to the radionuclides content. In this study, mild acid treated residual phosphogypsum was stabilized with Lime Fly Ash (LFA) binder, and the geotec...

The removal and recovery of metals from wastewater has been a subject of significant importance due the negative impact these toxic metals have on human health and the environment as a result of water and soil pollution. Increased use of the metals and chemicals in the process industries has resulted in generation of large quantity of effluents tha...

The Gold mining generates large volumes of tailings, with consequent disposal and environmental problems. Iron tends to react with sulphur to form pyrite and pyrrhotite which then react with rain water forming acid rain. The study focuses on the removal of iron (Fe) from Gold Mine tailings; Fe was leached using citric acid as a leaching reagent. Th...

The removal and recovery of metals from wastewater has been a subject of significant importance due the negative impact these toxic metals have on human health and the environment as a result of water and soil pollution. Increased use of the metals and chemicals in the process industries has resulted in generation of large quantity of effluents tha...

The work demonstrates the performance of polyamide membrane in the removal of manganese ions from single salt aqueous solution simulating real acid mine drainage. The membrane was tested using a dead-end filtration cell with manganese sulphate was used to prepare a feed solution. The membrane flux and metal rejection was evaluated. Effect of operat...

The worldwide known treatment processes of acid mine drainage result into the formation of hydrous ferric oxides that is amorphous, poorly crystalline and into the generation of hazardous voluminous sludge posing threat to the environment. Applicable treatment technologies to treat hazardous solid material and produce useful products are limited an...

Removal and recovery of heavy metals from effluent are major concerns due to diminishing fresh water resources, depletion of exploitable ores and human and environmental health concerns. The objective of this work was to efficiently recover heavy metals from effluent in their elemental form as metallic powder by reduction crystallization. This meth...

Due to the fast depletion of water reserves globally, the toxicity of heavy metals and the negative impact posed to the environment; the current focus in wastewater treatment is now on the removal and re-use of these heavy metals rather than removal and disposal in landfills. This study investigated the use of hydrazine as a reducing agent to remov...

This study was carried out to develop a flotation procedure for an oxide copper ore from a Region in Central Africa for producing an 18% copper concentrate for downstream processing at maximum recovery from a 4% copper feed grade. The copper recoveries achieved from the test work were less than 50% despite changes in reagent conditions (multistage...

This study investigated possible ways to improve the efficiency of the platinum precipitation process using ammonium chloride by reducing the platinum content reporting to the effluent. The ore treated consist of five platinum group metals namely, ruthenium, rhodium, iridium, platinum, palladium and a precious metal gold. Gold, ruthenium, rhodium a...