Activated carbon from lignocellulosic waste residues : effect of activating agent on porosity characteristics and use as adsorbents for organic species
- Olorundare, O.F., Msagati, T.A.M., Krause, R.W.M., Okonkwo, J.O., Mamba, B.B.
- Authors: Olorundare, O.F. , Msagati, T.A.M. , Krause, R.W.M. , Okonkwo, J.O. , Mamba, B.B.
- Date: 2014
- Subjects: Activated carbon , Maize tassel
- Type: Article
- Identifier: uj:5492 , http://hdl.handle.net/10210/13613
- Description: This paper reports on the effect of activating agents such as the impregnation ratio of phosphoric acid (1:1–1:5) at constant activation temperature on the performance of porous activated carbon from waste residues (maize tassel). The variation in the impregnation ratio of the produced activated carbon (AC) from 1:1 to 1:5 enabled the preparation of a high surface area (1,263 m2/g) and a large pore volume (1.592 cm3/g) of AC produced from maize tassel (MT) using a convectional chemical activating agent (phosphoric acid). Impregnation ratios (IR) of the precursors were varied between 1:1 and 1:5 in which it was found that the ratio of 1:4 was optimal based on the high surface area, while 1:5 has the optimal pore volume value for the produced activated carbon.
- Full Text:
- Authors: Olorundare, O.F. , Msagati, T.A.M. , Krause, R.W.M. , Okonkwo, J.O. , Mamba, B.B.
- Date: 2014
- Subjects: Activated carbon , Maize tassel
- Type: Article
- Identifier: uj:5492 , http://hdl.handle.net/10210/13613
- Description: This paper reports on the effect of activating agents such as the impregnation ratio of phosphoric acid (1:1–1:5) at constant activation temperature on the performance of porous activated carbon from waste residues (maize tassel). The variation in the impregnation ratio of the produced activated carbon (AC) from 1:1 to 1:5 enabled the preparation of a high surface area (1,263 m2/g) and a large pore volume (1.592 cm3/g) of AC produced from maize tassel (MT) using a convectional chemical activating agent (phosphoric acid). Impregnation ratios (IR) of the precursors were varied between 1:1 and 1:5 in which it was found that the ratio of 1:4 was optimal based on the high surface area, while 1:5 has the optimal pore volume value for the produced activated carbon.
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An exfoliated graphite-based Bisphenol A electrochemical sensor
- Ndlovu, T., Arotiba, O.A., Sampath, S., Mamba, B.B., Krause, R. W
- Authors: Ndlovu, T. , Arotiba, O.A. , Sampath, S. , Mamba, B.B. , Krause, R. W
- Date: 2012
- Subjects: Bisphenol A , Phenol , Electrode fouling , Exfoliated graphite electrodes , Bisphenol A electrochemical sensors
- Type: Article
- Identifier: uj:5795 , ISSN 1424-8220 , http://hdl.handle.net/10210/7803
- Description: The use of an exfoliated graphite (EG) electrode in the square wave voltammetric detection of bisphenol A (a model phenolic pollutant) in water, whereby the phenolic electrode fouling challenge is mitigated, is described. The oxidation peak of BPA was observed at about 0.45 V in phosphate buffer solution at pH 10. The current response exhibited a linear relationship with the concentration over a range from 1.56 μM–50 μM. The detection limit was calculated to be 0.76 μM. The EG electrode surface was renewed after each measurement with excellent reproducibility. A real sample application was also investigated.
- Full Text:
- Authors: Ndlovu, T. , Arotiba, O.A. , Sampath, S. , Mamba, B.B. , Krause, R. W
- Date: 2012
- Subjects: Bisphenol A , Phenol , Electrode fouling , Exfoliated graphite electrodes , Bisphenol A electrochemical sensors
- Type: Article
- Identifier: uj:5795 , ISSN 1424-8220 , http://hdl.handle.net/10210/7803
- Description: The use of an exfoliated graphite (EG) electrode in the square wave voltammetric detection of bisphenol A (a model phenolic pollutant) in water, whereby the phenolic electrode fouling challenge is mitigated, is described. The oxidation peak of BPA was observed at about 0.45 V in phosphate buffer solution at pH 10. The current response exhibited a linear relationship with the concentration over a range from 1.56 μM–50 μM. The detection limit was calculated to be 0.76 μM. The EG electrode surface was renewed after each measurement with excellent reproducibility. A real sample application was also investigated.
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Assessing the effectiveness of a biological recovery of nickel for tailing dumps management
- Mamba, B.B., Barnard, T.G., Mulaba-Bafubiandi, A.F., Fosso-Kankeu, E.
- Authors: Mamba, B.B. , Barnard, T.G. , Mulaba-Bafubiandi, A.F. , Fosso-Kankeu, E.
- Date: 2011-04
- Subjects: Nickel mobilization , Bacillus subtilis , Sulfuric acid , Ore , Biological mobilization , Tailing dumps management
- Identifier: uj:5811 , http://hdl.handle.net/10210/7819
- Description: The mobilization of nickel from sulphide minerals using sulfuric acid and heterotrophic microorganism (Bacillus subtilis) was independently examined. The influences of parameters such as the concentration of acid and bacteria as well as reaction time were considered. Results of the monod-type kinetic study showed faster recovery of nickel from tailings (20 ppm/h) than from ore (8.07 ppm/h) by biological mobilization and similar trend with sulfuric acid.
- Full Text:
- Authors: Mamba, B.B. , Barnard, T.G. , Mulaba-Bafubiandi, A.F. , Fosso-Kankeu, E.
- Date: 2011-04
- Subjects: Nickel mobilization , Bacillus subtilis , Sulfuric acid , Ore , Biological mobilization , Tailing dumps management
- Identifier: uj:5811 , http://hdl.handle.net/10210/7819
- Description: The mobilization of nickel from sulphide minerals using sulfuric acid and heterotrophic microorganism (Bacillus subtilis) was independently examined. The influences of parameters such as the concentration of acid and bacteria as well as reaction time were considered. Results of the monod-type kinetic study showed faster recovery of nickel from tailings (20 ppm/h) than from ore (8.07 ppm/h) by biological mobilization and similar trend with sulfuric acid.
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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.
- Authors: Lobanga, K.P. , Haarhoff, J. , Mamba, B.B. , Van Staden, S.J.
- Date: 2011
- Subjects: Water - Purification - Adsorption , Organic water pollutants , Carbon, Activated , Water - Purification - Organic compounds removal
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/16647 , uj:15793 , Lobanga, K.P. et al.(2011) Comparitive study for the removal of natural organic matter from different raw waters by ion exchange. In: Proceedings of the 4th IWA Specialty Conference on NOM: From Source to Tap and Beyond, held in Costa Mesa, USA. 27-29 July 2011, 9 p.
- Description: Abstract South African water treatment plants mainly utilise surface water sources whose quality is continuously compromised due to indirect reuse and high return flows. In general the methods used by these water treatment plants are based on the removal of turbidity, various chemical contaminants and microorganisms. Recently introduced NOM regulations added the removal of natural organic matter (NOM) as a priority. Basic anion exchange resins are one way of NOM removal, reported on this paper. Due to the variability in the composition of NOM in natural raw water, eight natural raw waters were collected throughout South Africa as representative of the different water types of the country. They were collected three times during a period of eight months. The strong and weak – base anion resins used in the study were chosen for their availability and competitive price at the local market. The removal of the NOM fractions was assessed by measuring ultraviolet absorption at a wavelength of 254 nm (UV254). Freundlich equilibrium isotherms were fitted. It was observed that the Freundlich parameters K and n are related reducing the Freundlich isotherm to a single-parameter model. The two parameters cluster for some waters regardless of season. Two performance indicators, namely 65% initial UV254 removal and absolute level of 6 /m, were adopted. It was found that if the initial UV254 is less than about 15 /m the absolute level of 6 /m is reached first while when the initial UV254 is greater than 20 /m the removal of 65% of UV254 is reached first. It was also observed that the resin usage rate is not only dependent on the initial UV254 value but also on the nature and concentration of the NOM, indicating a need for a better NOM characterization.
- Full Text: false
- Authors: Lobanga, K.P. , Haarhoff, J. , Mamba, B.B. , Van Staden, S.J.
- Date: 2011
- Subjects: Water - Purification - Adsorption , Organic water pollutants , Carbon, Activated , Water - Purification - Organic compounds removal
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/16647 , uj:15793 , Lobanga, K.P. et al.(2011) Comparitive study for the removal of natural organic matter from different raw waters by ion exchange. In: Proceedings of the 4th IWA Specialty Conference on NOM: From Source to Tap and Beyond, held in Costa Mesa, USA. 27-29 July 2011, 9 p.
- Description: Abstract South African water treatment plants mainly utilise surface water sources whose quality is continuously compromised due to indirect reuse and high return flows. In general the methods used by these water treatment plants are based on the removal of turbidity, various chemical contaminants and microorganisms. Recently introduced NOM regulations added the removal of natural organic matter (NOM) as a priority. Basic anion exchange resins are one way of NOM removal, reported on this paper. Due to the variability in the composition of NOM in natural raw water, eight natural raw waters were collected throughout South Africa as representative of the different water types of the country. They were collected three times during a period of eight months. The strong and weak – base anion resins used in the study were chosen for their availability and competitive price at the local market. The removal of the NOM fractions was assessed by measuring ultraviolet absorption at a wavelength of 254 nm (UV254). Freundlich equilibrium isotherms were fitted. It was observed that the Freundlich parameters K and n are related reducing the Freundlich isotherm to a single-parameter model. The two parameters cluster for some waters regardless of season. Two performance indicators, namely 65% initial UV254 removal and absolute level of 6 /m, were adopted. It was found that if the initial UV254 is less than about 15 /m the absolute level of 6 /m is reached first while when the initial UV254 is greater than 20 /m the removal of 65% of UV254 is reached first. It was also observed that the resin usage rate is not only dependent on the initial UV254 value but also on the nature and concentration of the NOM, indicating a need for a better NOM characterization.
- Full Text: false
Fluorescent sensing of chlorophenols in water using an azo dye modified β-cyclodextrin polymer
- Ncube, P., Krause, R.W., Mamba, B.B.
- Authors: Ncube, P. , Krause, R.W. , Mamba, B.B.
- Date: 2011
- Subjects: Chemosensors , Chlorinated phenols , Chlorinated by-products , Spectrophotometry
- Type: Article
- Identifier: uj:5796 , ISSN 1424-8220 , http://hdl.handle.net/10210/7804
- Description: A water soluble azo dye modified β-cyclodextrin polymer 4 was synthesized and used as a chemosensor for the detection of chlorinated phenols, model chlorinated by-products (CBPs) of water treatment for drinking purposes. The characterization of the intermediates and the azo dye modified β-CD polymer was done by UV/Vis Spectrophotometry, FT-IR and 1H-NMR spectroscopies. The chlorophenols were capable of quenching the fluorescence of the polymer. The polymer showed greater sensitivity towards 2,4-dichlorophenol, with a sensitivity factor of 0.35 compared to 0.05 and 0.12 for phenol and 4-chlorophenol, respectively. The stability constants (Ks) of the pollutants were also determined by the Benesi-Hildebrand method to be 2.104 × 103 M−1 for 2,4-dichlorophenol and 1.120 × 102 M−1 for 4-chlorophenol.
- Full Text:
- Authors: Ncube, P. , Krause, R.W. , Mamba, B.B.
- Date: 2011
- Subjects: Chemosensors , Chlorinated phenols , Chlorinated by-products , Spectrophotometry
- Type: Article
- Identifier: uj:5796 , ISSN 1424-8220 , http://hdl.handle.net/10210/7804
- Description: A water soluble azo dye modified β-cyclodextrin polymer 4 was synthesized and used as a chemosensor for the detection of chlorinated phenols, model chlorinated by-products (CBPs) of water treatment for drinking purposes. The characterization of the intermediates and the azo dye modified β-CD polymer was done by UV/Vis Spectrophotometry, FT-IR and 1H-NMR spectroscopies. The chlorophenols were capable of quenching the fluorescence of the polymer. The polymer showed greater sensitivity towards 2,4-dichlorophenol, with a sensitivity factor of 0.35 compared to 0.05 and 0.12 for phenol and 4-chlorophenol, respectively. The stability constants (Ks) of the pollutants were also determined by the Benesi-Hildebrand method to be 2.104 × 103 M−1 for 2,4-dichlorophenol and 1.120 × 102 M−1 for 4-chlorophenol.
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Impact of alkalinity on the removal of natural organic matter from raw waters by enhanced coagulation
- Dlamini, S.P., Van Staden, S., Haarhoff, J., Mamba, B.B.
- Authors: Dlamini, S.P. , Van Staden, S. , Haarhoff, J. , Mamba, B.B.
- Date: 2011
- Subjects: Drinking water - Purification - South Africa , Water - Purification - Coagulation -South Africa , Organic water pollutants - South Africa , Ferric chloride
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/16804 , uj:15810 , Dlamini, S.P. et al.(2011) Impact of alkalinity on the removal of natural organic matter (NOM) on raw waters by enhanced coagulation (EC). 12th Waternet Conference, Maputo, Mozambique, 26-28 October 2011, 13 p.
- Description: Abstract Natural organic matter (NOM) in all soils, ground and surface waters cause negative effects in potable water quality (undesired colour, taste, odour, and bacterial re-growth in distribution systems). Numerous studies have also found that the reaction of NOM with oxidative chemicals during drinking water treatment processes can result to the formation of carcinogenic disinfection by-products (DBPs). Many countries including South Africa, have therefore established regulations to control and minimise NOM and its effects. Enhanced coagulation (EC), a multiple-objective chemical dosing strategy, offers a viable option for NOM removal, and this study explores its use for typical South African raw waters. A consistent and reproducible jar test procedure, simulating the actual coagulation and flocculation pre-treatment steps, was developed and used to investigate the treatability of NOM (measured as UV 254 nm) in all the source waters. Ferric chloride was used as the coagulant due to its extensive application in South Africa. Raw water samples representing the various water types found in the country were seasonally collected for investigation, thus corresponding to a year-long data collection period. Since the removal of NOM is linked to strict control of pH, the coagulant dosage for the jar tests aimed at specific pHs (pH 7.0, 6.0, 5.5, 5.0 and 4.5) with the use of titration curves. The response parameters for the tests were temperature, turbidity, pH and UV 254 nm. Algorithms of finding the optimum dosage for both turbidity and UV 254 nm removal were developed from jar tests and consistently applied to subsequent batch tests. The results of the study suggested that low-alkalinity waters are more amenable to coagulation than high-alkalinity waters. The results also led to the conclusion that the alkalinity and pH of a water are key factors influencing coagulation performance. The optimum pH for the waters fell within the range of 5.0 to 6.5.
- Full Text:
- Authors: Dlamini, S.P. , Van Staden, S. , Haarhoff, J. , Mamba, B.B.
- Date: 2011
- Subjects: Drinking water - Purification - South Africa , Water - Purification - Coagulation -South Africa , Organic water pollutants - South Africa , Ferric chloride
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/16804 , uj:15810 , Dlamini, S.P. et al.(2011) Impact of alkalinity on the removal of natural organic matter (NOM) on raw waters by enhanced coagulation (EC). 12th Waternet Conference, Maputo, Mozambique, 26-28 October 2011, 13 p.
- Description: Abstract Natural organic matter (NOM) in all soils, ground and surface waters cause negative effects in potable water quality (undesired colour, taste, odour, and bacterial re-growth in distribution systems). Numerous studies have also found that the reaction of NOM with oxidative chemicals during drinking water treatment processes can result to the formation of carcinogenic disinfection by-products (DBPs). Many countries including South Africa, have therefore established regulations to control and minimise NOM and its effects. Enhanced coagulation (EC), a multiple-objective chemical dosing strategy, offers a viable option for NOM removal, and this study explores its use for typical South African raw waters. A consistent and reproducible jar test procedure, simulating the actual coagulation and flocculation pre-treatment steps, was developed and used to investigate the treatability of NOM (measured as UV 254 nm) in all the source waters. Ferric chloride was used as the coagulant due to its extensive application in South Africa. Raw water samples representing the various water types found in the country were seasonally collected for investigation, thus corresponding to a year-long data collection period. Since the removal of NOM is linked to strict control of pH, the coagulant dosage for the jar tests aimed at specific pHs (pH 7.0, 6.0, 5.5, 5.0 and 4.5) with the use of titration curves. The response parameters for the tests were temperature, turbidity, pH and UV 254 nm. Algorithms of finding the optimum dosage for both turbidity and UV 254 nm removal were developed from jar tests and consistently applied to subsequent batch tests. The results of the study suggested that low-alkalinity waters are more amenable to coagulation than high-alkalinity waters. The results also led to the conclusion that the alkalinity and pH of a water are key factors influencing coagulation performance. The optimum pH for the waters fell within the range of 5.0 to 6.5.
- Full Text:
Optimized coagulation for the removal of natural organic matter (NOM) from low alkalinity : hardness South African raw waters
- Dlamini, S.P., Van Staden, S., Haarhoff, J., Mamba, B.B.
- Authors: Dlamini, S.P. , Van Staden, S. , Haarhoff, J. , Mamba, B.B.
- Date: 2011
- Subjects: Drinking water - Purification - South Africa , Water - Purification - Coagulation - South Africa , Organic water pollutants - South Africa
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/17129 , uj:15845 , Dlamini, S.P. et al. (2011) Optimized coagulation for the removal of natural organic matter (NOM) from low alkalinity : hardness South African raw waters. In: Proceedings of the 2nd Young Water Professionals of Southern Africa Conference, Pretoria, South Africa, 3-5 July 2011, 11p.
- Description: Abstract This example is to demonstrate the layout of the first page of a paper for Water Science and Technology. The authors’ family names should be given in full; their forenames should be given as abbreviations. The title, authors' names and addresses should be indented 1.5 cm from the left-hand margin of the text area; the abstract is indented 1.5 cm from both margins. The abstract itself, set in 10 pt type like the authors' addresses, should start about 9 cm down from the top of the text area. It should be a single paragraph. Please do not make reference citations in the abstract and keep within the limit of 200 words. It is followed by your choice of up to six keywords, listed alphabetically and separated by semi-colons.
- Full Text:
- Authors: Dlamini, S.P. , Van Staden, S. , Haarhoff, J. , Mamba, B.B.
- Date: 2011
- Subjects: Drinking water - Purification - South Africa , Water - Purification - Coagulation - South Africa , Organic water pollutants - South Africa
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/17129 , uj:15845 , Dlamini, S.P. et al. (2011) Optimized coagulation for the removal of natural organic matter (NOM) from low alkalinity : hardness South African raw waters. In: Proceedings of the 2nd Young Water Professionals of Southern Africa Conference, Pretoria, South Africa, 3-5 July 2011, 11p.
- Description: Abstract This example is to demonstrate the layout of the first page of a paper for Water Science and Technology. The authors’ family names should be given in full; their forenames should be given as abbreviations. The title, authors' names and addresses should be indented 1.5 cm from the left-hand margin of the text area; the abstract is indented 1.5 cm from both margins. The abstract itself, set in 10 pt type like the authors' addresses, should start about 9 cm down from the top of the text area. It should be a single paragraph. Please do not make reference citations in the abstract and keep within the limit of 200 words. It is followed by your choice of up to six keywords, listed alphabetically and separated by semi-colons.
- Full Text:
The response of typical South African raw waters to enhanced coagulation
- Dlamini, S.P., Haarhoff, J., Mamba, B.B., Van Staden, S. J.
- Authors: Dlamini, S.P. , Haarhoff, J. , Mamba, B.B. , Van Staden, S. J.
- Date: 2011
- Subjects: Water - Purification - Organic compounds , Organic water pollutants
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/16567 , uj:15786 , Dlamini, S.P. et al. 2011. The response of typical South African raw waters to enhanced coagulation. In: Proceedings of the 4th IWA Specialty Conference on NOM: From Source to Tap and Beyond, Costa Mesa, USA. 27-29 July 2011, 11 p.
- Description: Abstract: Drinking water treatment plants in South Africa rely almost entirely on surface water sources, which are often compromised due to high return flows and indirect reuse. The typical treatment plants focus on the removal of physical and microbial contaminants which include turbidity, colour, chemical compounds and microorganisms. A relatively new concern to this list is natural organic matter (NOM) which has become a major concern in potable water treatment due to its recent regulation. In this study, eight different raw water samples from the various water types found in the country were seasonally collected and treated for the removal UV absorbance at a wavelength of 254nm (UV254) using enhanced coagulation (EC). The efficacy of EC, which can be employed as a practical technology in the removal of both turbidity and NOM, was evaluated in remaining UV254 from these raw water sources. Jar tests were conducted, with ferric chloride used as the coagulant (due to its extensive use as a coagulant in the water treatment industry in South Africa) and specific pH values (initial water pH, 7.0, 6.0, 5.5, 5.0 and 4.5) were chosen as target values guiding the six different coagulant dosages for the jar tests. The pH of the low-alkalinity (<60mg/l CaCO3) raw waters were adjusted and raised by the addition of sodium carbonate. The response parameters of the tests were turbidity (NTU), pH and UV254. Algorithms for finding the optimum coagulant dosage for UV254 removal were developed and consistently applied to all the results. Results showed large variations in the nature of NOM across the country from SUVA values. From the UV254 values, the concentrations of NOM also varied greatly geographically than temporally. The general trend observed in the EC results suggested that the pH should always be dropped to between 4.5 and 7.0 to lower the amounts of UV254 and turbidity to reasonable levels.
- Full Text: false
- Authors: Dlamini, S.P. , Haarhoff, J. , Mamba, B.B. , Van Staden, S. J.
- Date: 2011
- Subjects: Water - Purification - Organic compounds , Organic water pollutants
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/16567 , uj:15786 , Dlamini, S.P. et al. 2011. The response of typical South African raw waters to enhanced coagulation. In: Proceedings of the 4th IWA Specialty Conference on NOM: From Source to Tap and Beyond, Costa Mesa, USA. 27-29 July 2011, 11 p.
- Description: Abstract: Drinking water treatment plants in South Africa rely almost entirely on surface water sources, which are often compromised due to high return flows and indirect reuse. The typical treatment plants focus on the removal of physical and microbial contaminants which include turbidity, colour, chemical compounds and microorganisms. A relatively new concern to this list is natural organic matter (NOM) which has become a major concern in potable water treatment due to its recent regulation. In this study, eight different raw water samples from the various water types found in the country were seasonally collected and treated for the removal UV absorbance at a wavelength of 254nm (UV254) using enhanced coagulation (EC). The efficacy of EC, which can be employed as a practical technology in the removal of both turbidity and NOM, was evaluated in remaining UV254 from these raw water sources. Jar tests were conducted, with ferric chloride used as the coagulant (due to its extensive use as a coagulant in the water treatment industry in South Africa) and specific pH values (initial water pH, 7.0, 6.0, 5.5, 5.0 and 4.5) were chosen as target values guiding the six different coagulant dosages for the jar tests. The pH of the low-alkalinity (<60mg/l CaCO3) raw waters were adjusted and raised by the addition of sodium carbonate. The response parameters of the tests were turbidity (NTU), pH and UV254. Algorithms for finding the optimum coagulant dosage for UV254 removal were developed and consistently applied to all the results. Results showed large variations in the nature of NOM across the country from SUVA values. From the UV254 values, the concentrations of NOM also varied greatly geographically than temporally. The general trend observed in the EC results suggested that the pH should always be dropped to between 4.5 and 7.0 to lower the amounts of UV254 and turbidity to reasonable levels.
- Full Text: false
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