Beneficiation of pyrolitic carbon black
- Pilusa, Jefrey, Muzenda, Edison
- Authors: Pilusa, Jefrey , Muzenda, Edison
- Date: 2013
- Subjects: Activated carbon , Briquettes , Waste tyre pyrolysis , Crude carbon black
- Type: Article
- Identifier: http://ujcontent.uj.ac.za8080/10210/385444 , uj:4843 , http://hdl.handle.net/10210/12510
- Description: This research investigated treatment of crude carbon black produced from pyrolysis of waste tyres in order to evaluate its quality and possible industrial applications. A representative sample of crude carbon black was dry screened to determine the initial particle size distribution. This was followed by pulverizing the crude carbon black and leaching in hot concentrated sulphuric acid for the removal of heavy metals and other contaminants. Analysis of the refined carbon black showed a significant improvement of the product quality compared to crude carbon black. It was discovered that refined carbon black can be further classified into multiple high value products for various industrial applications such as filler, paint pigment, activated carbon and fuel briquettes.
- Full Text:
- Authors: Pilusa, Jefrey , Muzenda, Edison
- Date: 2013
- Subjects: Activated carbon , Briquettes , Waste tyre pyrolysis , Crude carbon black
- Type: Article
- Identifier: http://ujcontent.uj.ac.za8080/10210/385444 , uj:4843 , http://hdl.handle.net/10210/12510
- Description: This research investigated treatment of crude carbon black produced from pyrolysis of waste tyres in order to evaluate its quality and possible industrial applications. A representative sample of crude carbon black was dry screened to determine the initial particle size distribution. This was followed by pulverizing the crude carbon black and leaching in hot concentrated sulphuric acid for the removal of heavy metals and other contaminants. Analysis of the refined carbon black showed a significant improvement of the product quality compared to crude carbon black. It was discovered that refined carbon black can be further classified into multiple high value products for various industrial applications such as filler, paint pigment, activated carbon and fuel briquettes.
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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.
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- 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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Granular activated carbon performance at three Southern African water treatment plants
- Authors: Olivier, Johan
- Date: 2011-12-07
- Subjects: Water treatment plants , Water purification , Activated carbon
- Type: Thesis
- Identifier: uj:1859 , http://hdl.handle.net/10210/4216
- Description: M. Ing.
- Full Text:
- Authors: Olivier, Johan
- Date: 2011-12-07
- Subjects: Water treatment plants , Water purification , Activated carbon
- Type: Thesis
- Identifier: uj:1859 , http://hdl.handle.net/10210/4216
- Description: M. Ing.
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Modulated synthesized Ni-based MOF with improved adsorptive desulfurization activity
- Mguni, Liberty L., Yao, Yali, Ren, Jianwei, Liu, Xinying, Hildebrandt, Diane
- Authors: Mguni, Liberty L. , Yao, Yali , Ren, Jianwei , Liu, Xinying , Hildebrandt, Diane
- Date: 2021
- Subjects: Modulated synthesis , Ni-MOF , Activated carbon
- Type: Article
- Identifier: http://hdl.handle.net/10210/487856 , uj:44425 , Citation : Mguni, Liberty L., et al. "Modulated synthesized Ni-based MOF with improved adsorptive desulfurization activity." Journal of Cleaner Production 323 (2021): 129196. , DOI: https://doi.org/10.1016/j.jclepro.2021.129196
- Description: Abstract :Metal-organic frameworks (MOFs) are promising adsorbents for adsorptive desulfurization (ADS) because MOF structure can be tuned to match the application. However, data on the ADS of liquid fuels using Ni-BDC are still scarce. In this study, modulated synthesis was used to prepare a group of Ni-doped MOF absorbents using formic acid as the modulator. The activities of these adsorbents for the ADS of model fuels were investigated, with initial sulfur concentrations of 150, 151, and 153 ppm for thiophene (TH), dibenzothiophene (DBT), and 4,6-dimethyldibenzothiophene (4,6 DMDBT), respectively. Although Ni-doping decreased the crystallinity and crystallite size of the MOFs, the addition of formic acid significantly increased both the crystallite size and crystallinity of all the (xNi/Zn)-BDC materials. In addition, it was observed that modulated synthesis reduced the interpenetration of the MOF-5 crystallites. The adsorption experimental results showed that the modulated synthesis of Ni-BDC using formic acid improved the overall adsorptive activity of Ni-BDC almost twofold. This increase in activity was attributed to increased crystallinity and a higher number of atoms with low coordination for modulated Ni-BDC compared with MOF-5 (100). Formic acid as a modulator was observed to have three effects: i) accelerating MOF synthesis, ii) modulating crystallite size, and iii) controlling crystallinity. The most active adsorbent, Ni-BDC treated with formic acid, was observed to have higher activity toward TH than DBT and 4,6 DMDBT. The overall adsorption capacity and partition coefficient for this adsorbent were 4.14 mg/g and 0.053 mg/g/ppm, respectively.
- Full Text:
- Authors: Mguni, Liberty L. , Yao, Yali , Ren, Jianwei , Liu, Xinying , Hildebrandt, Diane
- Date: 2021
- Subjects: Modulated synthesis , Ni-MOF , Activated carbon
- Type: Article
- Identifier: http://hdl.handle.net/10210/487856 , uj:44425 , Citation : Mguni, Liberty L., et al. "Modulated synthesized Ni-based MOF with improved adsorptive desulfurization activity." Journal of Cleaner Production 323 (2021): 129196. , DOI: https://doi.org/10.1016/j.jclepro.2021.129196
- Description: Abstract :Metal-organic frameworks (MOFs) are promising adsorbents for adsorptive desulfurization (ADS) because MOF structure can be tuned to match the application. However, data on the ADS of liquid fuels using Ni-BDC are still scarce. In this study, modulated synthesis was used to prepare a group of Ni-doped MOF absorbents using formic acid as the modulator. The activities of these adsorbents for the ADS of model fuels were investigated, with initial sulfur concentrations of 150, 151, and 153 ppm for thiophene (TH), dibenzothiophene (DBT), and 4,6-dimethyldibenzothiophene (4,6 DMDBT), respectively. Although Ni-doping decreased the crystallinity and crystallite size of the MOFs, the addition of formic acid significantly increased both the crystallite size and crystallinity of all the (xNi/Zn)-BDC materials. In addition, it was observed that modulated synthesis reduced the interpenetration of the MOF-5 crystallites. The adsorption experimental results showed that the modulated synthesis of Ni-BDC using formic acid improved the overall adsorptive activity of Ni-BDC almost twofold. This increase in activity was attributed to increased crystallinity and a higher number of atoms with low coordination for modulated Ni-BDC compared with MOF-5 (100). Formic acid as a modulator was observed to have three effects: i) accelerating MOF synthesis, ii) modulating crystallite size, and iii) controlling crystallinity. The most active adsorbent, Ni-BDC treated with formic acid, was observed to have higher activity toward TH than DBT and 4,6 DMDBT. The overall adsorption capacity and partition coefficient for this adsorbent were 4.14 mg/g and 0.053 mg/g/ppm, respectively.
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Treatability of South African surface waters by activated carbon
- Lobanga, K.P, Haarhoff, J., Van Staden, S.J.
- Authors: Lobanga, K.P , Haarhoff, J. , Van Staden, S.J.
- Date: 2013
- Subjects: Activated carbon , Natural organic matter , Surface water , Ultraviolet absorbance
- Type: Article
- Identifier: uj:4834 , ISSN 0378-4738 , http://hdl.handle.net/10210/12480
- Description: Natural organic matter (NOM) in water resources for drinking purposes can be removed by different methods, including activated carbon adsorption. Due to the variability of NOM in natural waters, both in terms of its nature and its concentration, a study was undertaken to investigate NOM removal for a wide range of South African surface waters, sampled at different periods, by the use of granular activated carbon (GAC). NOM removal was assessed by measuring the ultraviolet (UV) absorbance at 3 wavelengths, namely, 254 nm (UV254), 272 nm (UV272) and 300 nm (UV300). A comparison of data between the three wavelengths showed that any of the three wavelengths can be used to assess NOM removal by GAC, which is well described by the Freundlich equilibrium equation. A treatment target of 40% removal of initial UV254 absorbance was considered. It was observed that, although the GAC dosage was generally a function of the initial UV254 absorbance, differences existed between waters. This suggests that GAC usage rate is not only a function of the initial UV absorbance but also of the NOM composition, indicating a need for improved NOM characterisation. Comparison between the UV absorbance and dissolved organic carbon (DOC) data suggested that for some waters UV254 absorbance can be used as a rapid substitute for DOC. Finally, the high GAC dosage rates required for the target criterion revealed that the process is inadequate for use at the initial stage of raw water treatment; GAC adsorption should be used at later stages of drinking water treatment.
- Full Text:
- Authors: Lobanga, K.P , Haarhoff, J. , Van Staden, S.J.
- Date: 2013
- Subjects: Activated carbon , Natural organic matter , Surface water , Ultraviolet absorbance
- Type: Article
- Identifier: uj:4834 , ISSN 0378-4738 , http://hdl.handle.net/10210/12480
- Description: Natural organic matter (NOM) in water resources for drinking purposes can be removed by different methods, including activated carbon adsorption. Due to the variability of NOM in natural waters, both in terms of its nature and its concentration, a study was undertaken to investigate NOM removal for a wide range of South African surface waters, sampled at different periods, by the use of granular activated carbon (GAC). NOM removal was assessed by measuring the ultraviolet (UV) absorbance at 3 wavelengths, namely, 254 nm (UV254), 272 nm (UV272) and 300 nm (UV300). A comparison of data between the three wavelengths showed that any of the three wavelengths can be used to assess NOM removal by GAC, which is well described by the Freundlich equilibrium equation. A treatment target of 40% removal of initial UV254 absorbance was considered. It was observed that, although the GAC dosage was generally a function of the initial UV254 absorbance, differences existed between waters. This suggests that GAC usage rate is not only a function of the initial UV absorbance but also of the NOM composition, indicating a need for improved NOM characterisation. Comparison between the UV absorbance and dissolved organic carbon (DOC) data suggested that for some waters UV254 absorbance can be used as a rapid substitute for DOC. Finally, the high GAC dosage rates required for the target criterion revealed that the process is inadequate for use at the initial stage of raw water treatment; GAC adsorption should be used at later stages of drinking water treatment.
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Simulation studies on the co-production of syngas and activated carbon from waste tyre gasification using different reactor configurations
- Fajimi, Lanrewaju I., Oboirien, Bilainu O., Adams, Thomas A.
- Authors: Fajimi, Lanrewaju I. , Oboirien, Bilainu O. , Adams, Thomas A.
- Date: 2021
- Subjects: Tyre gasification , Activated carbon , Fluidized bed
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10210/487939 , uj:44435 , Citation: Fajimi, L.I., Oboirien, B.O. & Adams, T.A. 2021. Simulation studies on the co-production of syngas and activated carbon from waste tyre gasification using different reactor configurations.
- Description: Abstract: Gasification is one of the most efficient thermo-chemical conversion processes for transforming waste tyres into syngas and high-valued solid carbon products such as activated carbon (AC). This study evaluated the coproduction of syngas and AC in three reactor configurations: fluidized bed, fixed bed, and rotary kiln at the systems level. A single-stage steam gasification and char activation process was simulated using Aspen Plus V10 software. The effects of gasification parameters such as equivalence ratio (ER) and steam-to-fuel ratio (SFR) were investigated and compared. The best conditions for the co-production of syngas and AC in the reactors were evaluated and compared. Brunauer-Emmett-Teller (BET) computational analysis was used to predict the surface area of the AC. The fluidized bed gasifier has the potential to produce syngas with a low heating value (LHV) of 6.67 MJ/Nm3, cold gas efficiency (CGE) of 82.4%LHV, AC with BET surface area of 698.63 m2/g and a carbon conversion ratio (CCR) of 92.5%, the fixed bed gasifier has a syngas LHV of 6.25 MJ/Nm3, CGE of 85.9%LHV, AC with BET surface area of 432.51 m2/g and CCR of 97.3% and the rotary kiln gasifier has a syngas LHV of 5.96 MJ/Nm3, CGE of 74%LHV, AC with BET surface area of 661.73 m2/g and CCR of 93%.
- Full Text:
- Authors: Fajimi, Lanrewaju I. , Oboirien, Bilainu O. , Adams, Thomas A.
- Date: 2021
- Subjects: Tyre gasification , Activated carbon , Fluidized bed
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10210/487939 , uj:44435 , Citation: Fajimi, L.I., Oboirien, B.O. & Adams, T.A. 2021. Simulation studies on the co-production of syngas and activated carbon from waste tyre gasification using different reactor configurations.
- Description: Abstract: Gasification is one of the most efficient thermo-chemical conversion processes for transforming waste tyres into syngas and high-valued solid carbon products such as activated carbon (AC). This study evaluated the coproduction of syngas and AC in three reactor configurations: fluidized bed, fixed bed, and rotary kiln at the systems level. A single-stage steam gasification and char activation process was simulated using Aspen Plus V10 software. The effects of gasification parameters such as equivalence ratio (ER) and steam-to-fuel ratio (SFR) were investigated and compared. The best conditions for the co-production of syngas and AC in the reactors were evaluated and compared. Brunauer-Emmett-Teller (BET) computational analysis was used to predict the surface area of the AC. The fluidized bed gasifier has the potential to produce syngas with a low heating value (LHV) of 6.67 MJ/Nm3, cold gas efficiency (CGE) of 82.4%LHV, AC with BET surface area of 698.63 m2/g and a carbon conversion ratio (CCR) of 92.5%, the fixed bed gasifier has a syngas LHV of 6.25 MJ/Nm3, CGE of 85.9%LHV, AC with BET surface area of 432.51 m2/g and CCR of 97.3% and the rotary kiln gasifier has a syngas LHV of 5.96 MJ/Nm3, CGE of 74%LHV, AC with BET surface area of 661.73 m2/g and CCR of 93%.
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Granular activated carbon management at a water treatment plant
- Authors: Clements, Michele
- Date: 2009-02-26T12:16:56Z
- Subjects: Water treatment plants , Water purification , Water purification filtration , Activated carbon
- Type: Thesis
- Identifier: uj:8148 , http://hdl.handle.net/10210/2155
- Description: M.Ing. , The Rietvlei Water Treatment Plant was extended with a granular activated carbon (GAC) filtration system after an exhaustive series of tests, which were started in 1994. Upon commissioning towards the middle of 1999, a year of close monitoring followed to measure the GAC performance at full-scale. After verification that the GAC does indeed ensure a high quality product under all conditions, the emphasis shifted to the optimisation of the GAC handling and regeneration system. Frequently moving the entire GAC inventory from the filters to an off-site regeneration plant and back requires significant operational effort and contributes a major part of the total cost of the GAC system. A number of systematic investigations were carried out in response to a number of practical questions that arose at Rietvlei. The first part of the study was directed towards tracking and quantifying the GAC on and off site. The main findings were that 10.0% of the GAC is lost from the filter during backwashing (0.3%) and removal of GAC from the filter for regeneration (9.7%). The sump traps not all this GAC and 2.3% of the total inventory is lost to the river. Inserting a sieve at the outlet of the sump can eliminate this loss. A further 80.3% of the GAC in a filter is removed for regeneration, of which 18.7% is lost during the regeneration process. The minimising off this loss can only be achieved through the optimisation of the regeneration process, which falls within the domain of the regeneration contractor. The second part of the study was directed at the behaviour of the GAC whilst within the filter bed. The porosity and sphericity was determined by laboratory tests and calculations. The porosity was found to be 0.69 for the 12 x 40 size carbon and 0.66 for the 8 x 30 size carbon and the sphericity was found to be 0.67 for the 12 x 40 size carbon and 0.66 for the 8 x 30 size carbon. By using a calibrated bed expansion model, the bed expansion could be calculated at 9°C and 23°C for the two carbons gradings; the maximum temperature range experienced at Rietvlei. The main finding of this part of the study was that the average available freeboard is 650 mm for the 12 x 40 grading and 430 mm for the 8 x 30 grading, and therefore no GAC should wash over the weir at all during backwashing. The third part of the study measured the physical changes of the GAC found at different points in the GAC cycle. The main findings were that the small fraction of GAC washed out of the bed during backwashing and removal has a finer grading, higher apparent density and lower adsorption capacity than the GAC in the filter bed. There seems to be no marked attrition of the carbon or generation of fines during the removal and transport of the GAC to the regeneration plant. After regeneration, there was a 7% decrease in apparent density and a 30% increase in adsorption capacity. The final part of the study correlated the adsorption capacity of the GAC with its time in use as well as UV254 removal. After regeneration, UV254 removal begins at approximately 20% and declines to 14% after 400 days of operation, and to 10% after 600 days. After regeneration, the iodine number begins at approximately 800, declines to 600 after 400 days of operation, and to 500 after 600 days.
- Full Text:
- Authors: Clements, Michele
- Date: 2009-02-26T12:16:56Z
- Subjects: Water treatment plants , Water purification , Water purification filtration , Activated carbon
- Type: Thesis
- Identifier: uj:8148 , http://hdl.handle.net/10210/2155
- Description: M.Ing. , The Rietvlei Water Treatment Plant was extended with a granular activated carbon (GAC) filtration system after an exhaustive series of tests, which were started in 1994. Upon commissioning towards the middle of 1999, a year of close monitoring followed to measure the GAC performance at full-scale. After verification that the GAC does indeed ensure a high quality product under all conditions, the emphasis shifted to the optimisation of the GAC handling and regeneration system. Frequently moving the entire GAC inventory from the filters to an off-site regeneration plant and back requires significant operational effort and contributes a major part of the total cost of the GAC system. A number of systematic investigations were carried out in response to a number of practical questions that arose at Rietvlei. The first part of the study was directed towards tracking and quantifying the GAC on and off site. The main findings were that 10.0% of the GAC is lost from the filter during backwashing (0.3%) and removal of GAC from the filter for regeneration (9.7%). The sump traps not all this GAC and 2.3% of the total inventory is lost to the river. Inserting a sieve at the outlet of the sump can eliminate this loss. A further 80.3% of the GAC in a filter is removed for regeneration, of which 18.7% is lost during the regeneration process. The minimising off this loss can only be achieved through the optimisation of the regeneration process, which falls within the domain of the regeneration contractor. The second part of the study was directed at the behaviour of the GAC whilst within the filter bed. The porosity and sphericity was determined by laboratory tests and calculations. The porosity was found to be 0.69 for the 12 x 40 size carbon and 0.66 for the 8 x 30 size carbon and the sphericity was found to be 0.67 for the 12 x 40 size carbon and 0.66 for the 8 x 30 size carbon. By using a calibrated bed expansion model, the bed expansion could be calculated at 9°C and 23°C for the two carbons gradings; the maximum temperature range experienced at Rietvlei. The main finding of this part of the study was that the average available freeboard is 650 mm for the 12 x 40 grading and 430 mm for the 8 x 30 grading, and therefore no GAC should wash over the weir at all during backwashing. The third part of the study measured the physical changes of the GAC found at different points in the GAC cycle. The main findings were that the small fraction of GAC washed out of the bed during backwashing and removal has a finer grading, higher apparent density and lower adsorption capacity than the GAC in the filter bed. There seems to be no marked attrition of the carbon or generation of fines during the removal and transport of the GAC to the regeneration plant. After regeneration, there was a 7% decrease in apparent density and a 30% increase in adsorption capacity. The final part of the study correlated the adsorption capacity of the GAC with its time in use as well as UV254 removal. After regeneration, UV254 removal begins at approximately 20% and declines to 14% after 400 days of operation, and to 10% after 600 days. After regeneration, the iodine number begins at approximately 800, declines to 600 after 400 days of operation, and to 500 after 600 days.
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