Showing items 1 - 13 of 13

Your selections:

Absorption of heavy metals and neutralisation of acid mine drainage using clay minerals

- Falayi, Thabo

Activated carbon from maize tassels and polymer composites for water decontamination

- Olorundare, Oluwasayo Folasayo

  • Authors: Olorundare, Oluwasayo Folasayo
  • Date: 2014-07-15
  • Subjects: Carbon, Activated , Water - Purification - Adsorption , Agricultural wastes , Composite materials
  • Type: Thesis
  • Identifier: uj:11657 , http://hdl.handle.net/10210/11380
  • Description: Ph.D. (Chemistry) , This study presents work on the preparation, characterisation and application of agricultural waste residue, maize tassel in the production of activated carbon (AC) using both physical and chemical methods of activation in their production. The activated carbon produced from maize tassel (MTAC) or steam-produced activated carbon (STAC) were later added as a filler – together with beta-cyclodextrin (β-CD), and raw tassel (RT) – in the production of polyurethane composite adsorbent (PUCAD) material for the removal of selected inorganic (such as Cd2+, Cr3+, Pb2+) and organic pollutants (phenolic compound - bisphenol A (BPA), ortho-nitrophenol (O-NTP), para-chlorophenol (PCP), polychlorinated biphenyl (PCB), and methylene blue (MB) as adsorbate/analytes from aqueous medium. Both batch and solid-phase extraction adsorption methods (SPE), were used for separation and preconcentration. The investigations included reactivity using Fourier transform infrared (FT-IR) spectroscopy, surface morphology analysis using scanning electron microscopy (SEM), thermal stability using thermogravimetric analysis (TGA), heat flow using differential scanning calorimetry (DSC), and crystallinity using X-ray diffraction (XRD) coupled with energy dispersive X-ray spectrometry (EDX). The FT-IR analysis revealed that there was interaction between the polymeric material and all the fillers. The hydrogen bonding and N-H group interaction between all the materials and the polyurethane polymer composite (PCAD) showed compatibility between the polymeric materials and the fillers.
  • Full Text:

Comparative study for the removal of natural organic matter from different raw waters by ion exchange

- Lobanga, K.P., Haarhoff, J., Mamba, B.B., Van Staden, S.J.

Hybrid ion exchanger supported metal hydroxides for the removal of phosphate from wastewater

- De Kock, Luéta-Ann

  • Authors: De Kock, Luéta-Ann
  • Date: 2015-11-12
  • Subjects: Phosphatee - Synthesis , Composite materials , Sewage disposal plants , Sewage - Purification - Biological treatment , Water - Purification - Adsorption
  • Type: Thesis
  • Identifier: uj:14560 , http://hdl.handle.net/10210/15093
  • Description: Ph.D. (Chemistry) , Phosphorus in the form of phosphate needs to be removed from the aqueous environment as it is primarily responsible for eutrophication of water bodies. In an attempt to limit the discharged of phosphorus into the aqueous environment, the phosphate discharge limits for wastewater treatment plants have been decreased. These limits are not easily or economically met by current phosphorus removal technologies. In addition phosphorus is a non-renewable resource. To ensure the ongoing quality of water bodies and security of food production it is vital that phosphate in water be removed and recovered. In order to address these issues, novel hybrid metal oxide ion exchange resins based on Fe(III), Cu(II), Mn(IV and Ti(IV) oxides have been prepared and their phosphate adsorption characteristics determined.
  • Full Text:

Mixed-metal oxide conducting polymer nanocomposites for the removal of fluoride and chromium(VI) from aqueous solution

- Chigondo, Marko

  • Authors: Chigondo, Marko
  • Date: 2018
  • Subjects: Nanocomposites (Materials) , Water - Purification - Adsorption , Water - Purification - Chromium removal , Water - Purification - Fluoride removal
  • Language: English
  • Type: Doctoral (Thesis)
  • Identifier: http://hdl.handle.net/10210/292685 , uj:31810
  • Description: Abstract: Water is an indispensable natural resource for sustaining life which is undoubtedly not free in all places. The chemical composition of surface or underground waters is one of the principal aspects upon which the relevancy of water for domestic, industrial or agricultural purposes hinges upon. Inorganic anions are commonly in existence in water; nonetheless, some of these including oxy-anions, are undesirable and continually accountable for the grave environmental and health problems. Such ions like arsenic (As(V)), hexavalent chromium(Cr(VI)), fluoride (F‒) phosphate (PO43‒) and nitrate (NO3‒) when in exceeding maximum limits, constitute some of the most hazardous water pollutants. Fluoride, at low a concentration of 0.8-1.5 mg/L as recommended by World Health Organisation (WHO) can prevent tooth decay and contribute to the development of strong bones, especially in young children. However, at higher concentrations it has catastrophic health effects ranging from dental related problems to debilitating skeletal fluorosis as well as affecting body parts like the muscles, brain, lungs, kidneys, thyroid, reproduction and enzymes. Its high concentration in ground water is primarily owing to the weathering of fluoride rich minerals, high ash volcanic eruptions and many anthropogenic activities. On the other hand, industrial activities such as electroplating, leather tanning, dye production, ferrochrome production, wood preservation, mining and paints manufacture have indirectly led to the discharge of Cr(VI) ions into environmental water. Cr(VI) is one of the most toxic, highly soluble and mobile anions in the environment which causes health problems in the form of dermatitis, damage to the liver, lung and skin cancer, skin irritation and internal haemorrhage. The WHO recommended level of Cr(VI) is 0.1 mg/L in surface waters and 0.05 mg/L in drinking water. Consequently, sustainable technologies have been developed to remove fluoride and Cr(VI) ions from water ranging from chemical precipitation, reverse osmosis, electrochemical methods, adsorption, membrane processes, ion exchange and phytoremediation. Among these techniques, adsorption has shown superiority, attributed to its simplicity in design, low operating costs, efficiency and reversibility. Several adsorbents have been utilised for adsorption successfully. However, some drawbacks such as high cost, low selectivity, narrow pH ranges, low adsorption capacity, slow adsorption and poor mechanical strength have been encountered with some of the adsorbent materials. Nano-metal oxides (NMOs) and conduction polymers have a better potential as adsorbents physical and chemical properties. However they have problems of agglomeration, hence low adsorption capacity and difficult to separate from aqueous media. More studies on modification and... , Ph.D. (Chemistry)
  • Full Text:

Natural organic matter removal from surface waters by enhanced coagulation, granular activated carbon adsorption and Ion exchange

- Lobanga, Kaluka Paul

  • Authors: Lobanga, Kaluka Paul
  • Date: 2014-09-17
  • Subjects: Water - Purification - Adsorption , Water - Purification - Organic compounds removal , Carbon, Activated , Organic water pollutants
  • Type: Thesis
  • Identifier: uj:12322 , http://hdl.handle.net/10210/12109
  • Description: M.Ing. (Civil Engineering) , Natural organic matter (NOM) is a complex mixture of organic compounds resulting from the decay of plants and animals. When not properly removed, NOM reacts with disinfectants to form disinfection by-products, of which some are known to be carcinogenic. Regulations have become more and more stringent about the maximum level of NOM in drinking water. Different water treatment processes can be applied to remove NOM. However, because each process targets specific fractions of NOM, this results in the existence of recalcitrant NOM fractions that are not removed, for each treatment process. The main objective of the study was thus to investigate NOM removal by using three advanced water treatment processes alone and in combination. The processes used were enhanced coagulation, granular activated carbon adsorption and ion exchange resin processes. Strong and weak base ion exchange resins were used. Although NOM removal methods have been investigated intensively, little attention is given to a so-called “multi-barrier” approach of NOM removal through enhanced coagulation, granular activated carbon adsorption and ion exchange resin that could be applied in practice. In order to take the seasonal and geographical variability of NOM into account, water samples were collected at eight geographical areas over five to seven seasons from 2010 to 2013. Results showed that different treatment processes remove different NOM fractions with different efficiency. Results also confirmed that EC performs better than the adsorptive treatment processes. But the literature shows that NOM removal by EC is difficult for water with high alkalinity and low SUVA values, which is common with SA waters. The adsorptive processes used for NOM removal revealed that they are not viable options, because even low percentage of NOM removal would require high adsorbent dosages, which removes this approach as a practical option.
  • Full Text:

Polymeric nitrogen donor macro(meso)porous sorption materials for selected transition metals

- Mphanje, Kelebohile

Quaternized photocatalytic polymeric adsorbents for selective Cr(VI) and cyanide removal from simulated wastewater

- Masinga, Thobile

  • Authors: Masinga, Thobile
  • Date: 2018
  • Subjects: Chromium , Polymers - Absorption and adsorption , Water - Purification - Adsorption
  • Language: English
  • Type: Masters (Thesis)
  • Identifier: http://hdl.handle.net/10210/279554 , uj:30023
  • Description: M.Tech. (Chemistry) , Abstract: The dissertation reports on the preparation, characterization and applications of quaternized adsorbents for the adsorption and subsequent reduction of Cr(VI) and cyanide ions (CN-). The quaternized materials were based on poly(vinyl pyridine) and its polyacrylic acid copolymer deposited on activated carbon. The quaternization of the PVP-based adsorbents was done in order to modulate the charge on the nitrogen atom of the pyridine ring for better selectivity towards the anionic pollutants (Cr(VI) and CN- ions). Further modulation of the cationic centre was achieved through copolymerization of vinylpyridine and acrylic acid via radical polymerization to form 4PVP-co-PAA. On the other hand, these adsorbents were incorporated with TiO2 for the photo-reduction and photo-oxidation of Cr(VI) and CN- respectively. The main findings of the research are outlined below.  All the prepared materials were characterized using a variety of techniques. Characterization using FTIR confirmed the formation of the polymer adsorbents and their subsequent quaternization as indicated by the appearance of new bands at certain specific wavenumbers. The XRD and Raman spectroscopy showed the presence of both TiO2 and activated carbon, which proves the successful incorporation of the photocatalyst in the adsorbent materials. Microscopy (SEM and TEM) studies showed that TiO2 particles were uniformly dispersed when incorporated in activated carbon and polymeric materials.  The adsorbents were tested for the removal of Cr(VI) and its photo-reduction. It was found that the use of quaternized adsorbents for adsorption of Cr(VI) was optimal at pH 3 with up to 93%, e.g. removal of 93% and 90% were observed for AC/QP4VP (activated carbon supported quaternized poly-4-vinylpyridine) and AC/QP4VP-co-PAA (activated carbon supported quaternized polyvinylpyridine-co-polyacrylicacid) respectively. The adsorption was due to the positively charged nitrogen, which interacted with the negatively charged HCrO4- ion through electrostatic attraction. Using photo-reduction, the removal of Cr(VI) in solution was increased to 98% within 180 minutes. The chemistry between the 4-VP with Cr(VI) ions was interrogated using the UV-Vis spectroscopy. The coordination of the chromate ions to the...
  • Full Text:

Recovery of base metals from nitric and sulphiric solutions using carbon nanotubes

- Mgwetyana, Unathi

  • Authors: Mgwetyana, Unathi
  • Date: 2014-01-27
  • Subjects: Nanotubes , Extraction (Chemistry) , Heavy metals - Absorption and adsorption , Water - Purification - Adsorption
  • Type: Thesis
  • Identifier: uj:7961 , http://hdl.handle.net/10210/8861
  • Description: M.Tech. (Extraction Metallurgy) , For many decades, carbon nanotubes (CNTs) have been used as adsorbents for the removal of pollutants from wastewaters because of their unique properties such as inert surface, resistance to acid and base environment, rigidity and strength. Herein is a report of application of functionalised CNTs on the adsorption of metal ions from aqueous solutions and mine leachates. The CNTs were first synthesised in-house, purified, functionalised and characterised with various characterisation techniques: FTIR (Fourier Transform Infrared), SEM (Scanning Electron Microscopy, TEM (Transmission Electron Microscopy), EDS (Energy Dispersive Spectroscopy), Raman Spectroscopy, TGA (Thermal Gravimetric Analysis) and BET (Brunauer-Emmet-Teller). Together, these techniques gave substantiation for structure, surface and chemical modification of the synthesised moieties. After characterisation, the functional groups were attached to the walls of the tubes and this implies successful functionalisation...
  • Full Text:

Removal of hexavalent chromium using lignocellulosic tea factory waste as low cost adsorbent

- Sello, Julius M.

  • Authors: Sello, Julius M.
  • Date: 2016
  • Subjects: Factory and trade waste - Purification , Water - Purification - Adsorption , Sewage - Purification - Chromium removal
  • Language: English
  • Type: Masters (Thesis)
  • Identifier: http://hdl.handle.net/10210/85044 , uj:19295
  • Description: Abstract: Chromium has emerged as one of the extremely toxic heavy metals whose pollution has raised a lot of concerns globally. Due to the adverse impacts that hexavalent chromium (Cr(VI)) has on human health, a number of techniques such as; chemical precipitation, ion exchange and membrane filtration and so on have been dedicated to the remediation of this metal. However, such techniques generally suffer drawbacks related to low efficiency or high installation and operational costs. The present study was therefore aimed at the use of tea factory waste (TFW) collected from a tea factory in Mpumalanga, South Africa, as a low cost adsorbent for the removal of toxic hexavalent chromium from water. The adsorbent was characterized using ATR-FTIR, FE-SEM, XRD, BET, etc. Batch and fixed bed studies were performed to determine its efficiency of TFW for Cr(VI) adsorption. From batch studies, effect of critical parameters such as pH, temperature, adsorbent dose, initial adsorbate concentration, coexisiting ions and contact time were investigated. The adsorption of Cr(VI) on TFW followed Langmuir model with maximum adsorption capacity of 192.30 mg/g at pH 2, at 25 °C. The adsorption was favored at low pH values due to the nature of functional groups found on the TFW. Thermodynamic parameters such as ΔG°, ΔH° and ΔS° were also calculated, and revealed that the adsorption process is endothermic and spontaneous in nature. Furthermore, the adsorption data were modelled using various kinetic models such as pseudo-first-order, pseudo-second-order and intraparticle diffusion model, and the results indicate that the pseudo-second order model best describes the kinetics of the adsorption of Cr(VI) on TFW. From fixed bed studies, effects of flow rate, initial concentration and bed mass was also investigated to check the performance of the adsorbent. 9.54 L of contaminated water was successfully treated with 6 g of TFW at 50 mg/L influent concentration. The performance of the TFW bed highly depended on initial influent concentration, flow rate and adsorbent bed mass. , M.Sc. (Chemistry)
  • Full Text:

Removal of manganese(II) ion from wastewater using low cost adsorbents and exploration of the reuse of the manganese-loaded adsorbent in the sensing of volatile organic compounds

- Ngobeni, Daisy Delta

  • Authors: Ngobeni, Daisy Delta
  • Date: 2019
  • Subjects: Water - Purification - Adsorption , Sewage - Purification
  • Language: English
  • Type: Masters (Thesis)
  • Identifier: http://hdl.handle.net/10210/418470 , uj:35480
  • Description: Abstract: Manganese (Mn) is one of Earth's crust's most abundant metals. Manganese is present as a divalent ion (Mn2+) in groundwater and it is considered as a pollutant primarily due to its organoleptic properties. Therefore, manganese must be removed from wastewaters. Conventional physical and chemical treatments for the removal of Mn(II) from contaminated effluents are precipitation, filtration, ion exchange , adsorption and oxidation. These methods have several disadvantages, which include excessive requirements for reagents, unpredictable removal of metal ions, toxic sludge generation, etc. It has been discovered that the adsorption technique is one of the most effective methods for removing metal ions from aqueous solution and has, therefore, been used in this study. This dissertation therefore focuses on preparation of low-cost adsorbents for the removal of manganese from aqueous solution. Orange peels are low-cost material of interest due to their large surface areas, high swelling capacities, good mechanical strengths, and convenient use. The potential to use agricultural waste (orange peels) that litter our environment can, therefore, be a valuable resource for removing Mn(II) from aqueous solution... , M.Sc. (Chemistry)
  • Full Text:

Removal of natural organic matter from different raw waters by ion exchange resins

- Lobanga, K.P., Haarhoff, J., Van Staden, S.

Use of Moringa Oleifera seed as a flocculant, anti-microbial agent and metal bio-sorbent in water and wastewater treatment

- Ncube, Pauline

  • Authors: Ncube, Pauline
  • Date: 2016
  • Subjects: Sewage - Purification , Water - Purification - Adsorption , Flocculation , Coagulation
  • Language: English
  • Type: Masters (Thesis)
  • Identifier: http://hdl.handle.net/10210/233212 , uj:23806
  • Description: M.Tech. (Chemical Engineering) , Abstract: Milled Moringa Oleifera (M.O) seeds were characterised and used as a bio-sorbent in the removal of metals from acidic mineral effluents, coagulant/flocculent and antimicrobial agent in water and wastewater treatment. Biosorption experiments were conducted by means of agitation in a thermostatic shaker using synthetic acidic mineral wastewater consisting of 20 ppm Ni, 20 ppm Cu, 100 ppm Mn and 500 ppm Fe. The effects of solid loading, pH, contact time and temperature were investigated. Adsorption isotherms, kinetics and thermodynamics parameters were calculated from the experimental data obtained. The ability of milled spent Moringa seeds to be re-used (without recycling) and to be recycled was also investigated. Jar test experiments were conducted in order to evaluate the coagulation/flocculation process using synthetic turbid water. Optimum M.O dosage and TSS removal efficiency were determined from the experimental data obtained. The antimicrobial activity of M.O seeds was determined through experiments investigating the effect of raw seed extract and aqueous seed extract on coliforms and Heterotrophic Plate Count (HPC) bacteria. Metal removal followed the order: Ni > Cu > Fe > Mn. Metal removal efficiency increased with pH, time, % solid loading and temperature until sorption equilibrium was achieved. Optimum operating conditions achieved were pH = 3, Temperature = 308K, % solid loading = 10% and residence time of 60, 90, 90 and 120 minutes for Ni, Cu, Fe and Mn respectively. The bio-sorption process was feasible and spontaneous for Cu and Ni only as shown by the negative ΔG◦ values. These values increased on the negative scale with temperature (-80.3 to -2926.9 J/mol for Cu and -782.9 to -2647.3 J/mol for Ni) implying increased probability of the sorption process at higher temperatures. For all metals, ΔH◦ and ΔS◦ values were positive signifying the endothermic nature of the adsorption process and the increase in the degrees of freedom on the surface of the sorbent and disorderness of the system. For the adsorption reaction to proceed spontaneously, ΔG◦< 0, ΔS◦ > 0 and ΔH◦ > 0. The Langmuir model and second order kinetics best described the adsorption process for Ni, Cu and Fe. Ion exchange or chemisorption was the possible mechanism of adsorption as suggested by the Temkin model. FTIR spectrum suggested -C=O- to be the predominant functional group that binds and reacts with Me2+ ions. The spent milled seeds could be effectively re-used for metal removal for two cycles without desorption and could possibly be recycled for further use as bio sorbents for metal removal from AMD...
  • Full Text:
  • 1
  • Disclaimer
  • Privacy
  • Copyright
  • Contact