Jerome Andrew | Council for Scientific and Industrial Research (CSIR) (original) (raw)
Uploads
Papers by Jerome Andrew
Bleached hardwood and softwood South African kraft pulps were passed through a commercially avail... more Bleached hardwood and softwood South African kraft pulps were passed through a commercially available micro grinder for varying number of passes and the properties of the resultant pulps were assessed periodically using microscopy, Fourier transform infrared spectroscopy (FTIR), X-ray crystallography (XRD) and Thermogravimetric analysis (TGA). The ultrastructural analysis of the pulp fibres revealed that after 120 passes both hardwood and softwood bleached fibres showed the presence of cellulose nanofibres (CNFs). The FTIR analysis showed no modification to the cellulose structure and side groups upon treatment with the supermasscolloider (SMC). Both hardwood and softwood pulp fibres showed a decline in crystallinity after SMC treatment. For the hardwood pulps there were no major differences between the untreated pulps and those passed through the SMC. In the case of the softwood pulps, the SMC treatment resulted in more thermally stable CNFs compared with the untreated bleached pulps. This was observed at several levels of treatment (40, 120 and 200 passes). After 200 passes both the hardwood and softwood kraft pulp fibres produced CNFs with an average width of 11 nm and lengths with several micrometers.
Waste paper recycling in South Africa has grown to a respectable recovery rate of 43% in 2008. Pe... more Waste paper recycling in South Africa has grown to a respectable recovery rate of 43% in 2008. Pending legislation will further boost the recovery rate of recycled paper. Domestic household waste represents the major remaining source of recycled paper. This source will introduce greater variability into the waste streams entering the recycling mills, which will result in greater process variability, lower quality and operating difficulties. In this study, a typical deinking process was investigated using the techniques of experimental design to determine the relative effects of process chemical additions, pH, pulping and flotation times, pulping and flotation consistencies and pulping and flotation temperatures on the final deinked pulp properties. Samples of newsprint, magazines, and two grades of mixed office waste were pulped and deinked by flotation and washing in the laboratory. Handsheets were formed and measured for brightness, residual ink concentration and yield. A Plackett...
Tappi Journal
Ozone use in conjunction with chlorine dioxide during pulp bleaching offers several advantages ov... more Ozone use in conjunction with chlorine dioxide during pulp bleaching offers several advantages over conventional bleaching sequences that make use of chlorine dioxide only. Despite this, in South Africa, only one mill uses ozone. The current study was a preliminary investigation into the use of ozone in bleaching sequences for kraft pulps produced from South African Eucalyptus grandis wood chips, which typically contained high amounts of kraft pulps produced from South African Eucalyptus grandis wood chips, which typically contained high amounts of technologies used to remove HexA, such as acid hydrolysis (A) and hot chlorine dioxide (DHT) stages. Bleaching sequences using chlorine dioxide (i.e., OAD0ED1D2 and ODHTED1D2) were compared to bleaching sequences using ozone (i.e., OZD0ED1 and OAZD0ED1). The results showed that ozone preferentially reacted with HexA in the presence of lignin. When applied after oxygen delignification, ozone had the same HexA removal efficiencies as the A-...
Environmental scanning electron microscopy coupled with energy dispersive x-ray (ESEM/EDX) was op... more Environmental scanning electron microscopy coupled with energy dispersive x-ray (ESEM/EDX) was optimised to measure the penetration and diffusion of cooking liquor into Eucalyptus grandis wood chips during kraft pulping. The moisture content of the cooked wood chips influenced the ESEM/EDX measurement of sodium and sulphur, whilst the contribution of sodium and sulphur already present in the wood prior to pulping was negligible. Using the optimised ESEM/EDX method, investigations into the use of pulping aids during kraft pulping showed that the penetration and diffusion of sodium and sulphur was enhanced by the use of anthraquinone (AQ) and a combination of AQ and surfactant. As expected, chip thickness was found to influence the penetration and diffusion of cooking liquor into the wood structure during cooking. URI: http://www.tappsa.co.za/html_index_links/html_issue_5_2011/Peer%20Reviewed%20Paper.html http://hdl.handle.net/10204/5344
Nordic Pulp and Paper Research Journal
The removal of ink from recovered papers by flotation deinking is considered to be the “heart” of... more The removal of ink from recovered papers by flotation deinking is considered to be the “heart” of the paper recycling process. Attempts to model the deinking flotation process from first principles has resulted in complex and not readily usable models. Artificial neural networks are adept at modelling complex and poorly understood phenomena. Based on data generated in a laboratory, artificial neural network models were developed for the flotation deinking process. Representative samples of recycled newsprint, magazines and fine papers were pulped and deinked by flotation in the laboratory, under a wide variety of practical conditions. The brightness, residual ink concentration and the yield were measured and used to train artificial neural networks. Regressions of approximately 0.95, 0.85 and 0.79 respectively were obtained. These models were validated using actual plant data from three different deinking plants manufacturing seven different grades of recycled pulp. It was found tha...
Nordic Pulp and Paper Research Journal, 2014
BioResources, 2013
ABSTRACT The feasibility of enhancing the efficiency of the kraft pulping operations while at the... more ABSTRACT The feasibility of enhancing the efficiency of the kraft pulping operations while at the same time evolving the process into a biorefinery, and thus producing hemicelluloses together with paper products, was studied. Hardwood chips (Eucalyptus grandis) were pre-treated with green liquor prior to pulp production. At optimal pre- treatment conditions, the pH of the resulting extract was 7.8, the wood weight loss was 14%, and the hemicellulose extracted was almost 40 kg/ton of woodchips. In the subsequent kraft pulping, the resulting data revealed that the woodchips from which hemicellulose had been pre-extracted could be pulped much faster than woodchips pulped without hemicellulose extraction. As a result, to maintain the target kappa number, a 20% reduction in pulping chemicals was achievable. Hemicellulose pre-extraction led to a 10% reduction in black liquor solid contents. Moreover, the strength properties of the pulps produced with and without hemicellulose extraction were comparable. Industrial acceptance of this concept, however, still requires a more accurate understanding of the effect of specific mill operating conditions on mill energy balance. Careful economic assessment of the options for handling the calcium carbonate scale problem will also be required before the technology can be considered for implementation.
Abstr act An alternative way of fractionating lignocellulose biomass into its individual componen... more Abstr act An alternative way of fractionating lignocellulose biomass into its individual components, hemicelluloses, lignin and cellulose, was investigated. South African Eucalyptus grandis wood chips were fractionated using a combination of hot water and alkaline treatments with or without AQ. Initially, the biomass samples were treated in hot water to remove hemicelluloses. At optimum prefraction conditions, the data acquired revealed that almost 12 % of the E. grandis wood biomass could be recovered as hemicelluloses. When the hemicelluloses preextracted biomass was further treated using sodium hydroxide with or without AQ, the data indicated that the amount of lignin and cellulose that could be recovered was 22 and 36 %, respectively (as % of the wood mass). The substrate was characterised by a higher amount of a -cellulose (91-93 %), lower kappa no (12-13), viscosity (327-450 g mg/L) and DP (1078-1536). It was then presumed that such pulp could meet end-user requirement of the dissolving pulps. Industrial acceptance of this biomass fractionation concept, however, will further require careful assessments of various options for treating and purifying the hemicelluloses and lignin in their respect streams.
Vol 18, No 1 (2016) by Jerome Andrew
Two common Nigerian-grown biomasses, gmelina (Gmelina arborea) and bamboo (Bambusaa vulgaris) hav... more Two common Nigerian-grown biomasses, gmelina (Gmelina arborea) and bamboo (Bambusaa vulgaris) have been pulped and their fibre characteristics and paper properties examined. The results of their chemical compositions showed some fair similarities. The amount of glucose in the pulps of both biomasses indicated their suitability as lignocellulosic materials for pulping. Their pulp yield ranged between 48,0-54,1%, which fell within the acceptable range for good pulpwoods. The analysis of their fibre dimensions revealed that bamboo fibre has a wider fibre length distribution and higher fine length content. Gmelina and bamboo had weighted mean fibre lengths of 0,93 and 2,07 mm and mean fibre widths of 24,1 and 16,9 µm, respectively. The Runkel ratios of the samples were 0,4 (gmelina) and 0,9 (bamboo): this is indicative of their suitability for paper making. Mechanical properties of handsheets obtained from gmelina compared fairly well with South African pulpwoods (Eucalyptus grandis and Pinus paluta). Bamboo exhibited better tear index values than these woods but with lower sheet density and tensile index. These properties were significantly improved in handsheets obtained from blends of gmelina and bamboo, raising the prospect of producing paper from blends of both raw materials in Nigeria.
Bleached hardwood and softwood South African kraft pulps were passed through a commercially avail... more Bleached hardwood and softwood South African kraft pulps were passed through a commercially available micro grinder for varying number of passes and the properties of the resultant pulps were assessed periodically using microscopy, Fourier transform infrared spectroscopy (FTIR), X-ray crystallography (XRD) and Thermogravimetric analysis (TGA). The ultrastructural analysis of the pulp fibres revealed that after 120 passes both hardwood and softwood bleached fibres showed the presence of cellulose nanofibres (CNFs). The FTIR analysis showed no modification to the cellulose structure and side groups upon treatment with the supermasscolloider (SMC). Both hardwood and softwood pulp fibres showed a decline in crystallinity after SMC treatment. For the hardwood pulps there were no major differences between the untreated pulps and those passed through the SMC. In the case of the softwood pulps, the SMC treatment resulted in more thermally stable CNFs compared with the untreated bleached pulps. This was observed at several levels of treatment (40, 120 and 200 passes). After 200 passes both the hardwood and softwood kraft pulp fibres produced CNFs with an average width of 11 nm and lengths with several micrometers.
Waste paper recycling in South Africa has grown to a respectable recovery rate of 43% in 2008. Pe... more Waste paper recycling in South Africa has grown to a respectable recovery rate of 43% in 2008. Pending legislation will further boost the recovery rate of recycled paper. Domestic household waste represents the major remaining source of recycled paper. This source will introduce greater variability into the waste streams entering the recycling mills, which will result in greater process variability, lower quality and operating difficulties. In this study, a typical deinking process was investigated using the techniques of experimental design to determine the relative effects of process chemical additions, pH, pulping and flotation times, pulping and flotation consistencies and pulping and flotation temperatures on the final deinked pulp properties. Samples of newsprint, magazines, and two grades of mixed office waste were pulped and deinked by flotation and washing in the laboratory. Handsheets were formed and measured for brightness, residual ink concentration and yield. A Plackett...
Tappi Journal
Ozone use in conjunction with chlorine dioxide during pulp bleaching offers several advantages ov... more Ozone use in conjunction with chlorine dioxide during pulp bleaching offers several advantages over conventional bleaching sequences that make use of chlorine dioxide only. Despite this, in South Africa, only one mill uses ozone. The current study was a preliminary investigation into the use of ozone in bleaching sequences for kraft pulps produced from South African Eucalyptus grandis wood chips, which typically contained high amounts of kraft pulps produced from South African Eucalyptus grandis wood chips, which typically contained high amounts of technologies used to remove HexA, such as acid hydrolysis (A) and hot chlorine dioxide (DHT) stages. Bleaching sequences using chlorine dioxide (i.e., OAD0ED1D2 and ODHTED1D2) were compared to bleaching sequences using ozone (i.e., OZD0ED1 and OAZD0ED1). The results showed that ozone preferentially reacted with HexA in the presence of lignin. When applied after oxygen delignification, ozone had the same HexA removal efficiencies as the A-...
Environmental scanning electron microscopy coupled with energy dispersive x-ray (ESEM/EDX) was op... more Environmental scanning electron microscopy coupled with energy dispersive x-ray (ESEM/EDX) was optimised to measure the penetration and diffusion of cooking liquor into Eucalyptus grandis wood chips during kraft pulping. The moisture content of the cooked wood chips influenced the ESEM/EDX measurement of sodium and sulphur, whilst the contribution of sodium and sulphur already present in the wood prior to pulping was negligible. Using the optimised ESEM/EDX method, investigations into the use of pulping aids during kraft pulping showed that the penetration and diffusion of sodium and sulphur was enhanced by the use of anthraquinone (AQ) and a combination of AQ and surfactant. As expected, chip thickness was found to influence the penetration and diffusion of cooking liquor into the wood structure during cooking. URI: http://www.tappsa.co.za/html_index_links/html_issue_5_2011/Peer%20Reviewed%20Paper.html http://hdl.handle.net/10204/5344
Nordic Pulp and Paper Research Journal
The removal of ink from recovered papers by flotation deinking is considered to be the “heart” of... more The removal of ink from recovered papers by flotation deinking is considered to be the “heart” of the paper recycling process. Attempts to model the deinking flotation process from first principles has resulted in complex and not readily usable models. Artificial neural networks are adept at modelling complex and poorly understood phenomena. Based on data generated in a laboratory, artificial neural network models were developed for the flotation deinking process. Representative samples of recycled newsprint, magazines and fine papers were pulped and deinked by flotation in the laboratory, under a wide variety of practical conditions. The brightness, residual ink concentration and the yield were measured and used to train artificial neural networks. Regressions of approximately 0.95, 0.85 and 0.79 respectively were obtained. These models were validated using actual plant data from three different deinking plants manufacturing seven different grades of recycled pulp. It was found tha...
Nordic Pulp and Paper Research Journal, 2014
BioResources, 2013
ABSTRACT The feasibility of enhancing the efficiency of the kraft pulping operations while at the... more ABSTRACT The feasibility of enhancing the efficiency of the kraft pulping operations while at the same time evolving the process into a biorefinery, and thus producing hemicelluloses together with paper products, was studied. Hardwood chips (Eucalyptus grandis) were pre-treated with green liquor prior to pulp production. At optimal pre- treatment conditions, the pH of the resulting extract was 7.8, the wood weight loss was 14%, and the hemicellulose extracted was almost 40 kg/ton of woodchips. In the subsequent kraft pulping, the resulting data revealed that the woodchips from which hemicellulose had been pre-extracted could be pulped much faster than woodchips pulped without hemicellulose extraction. As a result, to maintain the target kappa number, a 20% reduction in pulping chemicals was achievable. Hemicellulose pre-extraction led to a 10% reduction in black liquor solid contents. Moreover, the strength properties of the pulps produced with and without hemicellulose extraction were comparable. Industrial acceptance of this concept, however, still requires a more accurate understanding of the effect of specific mill operating conditions on mill energy balance. Careful economic assessment of the options for handling the calcium carbonate scale problem will also be required before the technology can be considered for implementation.
Abstr act An alternative way of fractionating lignocellulose biomass into its individual componen... more Abstr act An alternative way of fractionating lignocellulose biomass into its individual components, hemicelluloses, lignin and cellulose, was investigated. South African Eucalyptus grandis wood chips were fractionated using a combination of hot water and alkaline treatments with or without AQ. Initially, the biomass samples were treated in hot water to remove hemicelluloses. At optimum prefraction conditions, the data acquired revealed that almost 12 % of the E. grandis wood biomass could be recovered as hemicelluloses. When the hemicelluloses preextracted biomass was further treated using sodium hydroxide with or without AQ, the data indicated that the amount of lignin and cellulose that could be recovered was 22 and 36 %, respectively (as % of the wood mass). The substrate was characterised by a higher amount of a -cellulose (91-93 %), lower kappa no (12-13), viscosity (327-450 g mg/L) and DP (1078-1536). It was then presumed that such pulp could meet end-user requirement of the dissolving pulps. Industrial acceptance of this biomass fractionation concept, however, will further require careful assessments of various options for treating and purifying the hemicelluloses and lignin in their respect streams.
Two common Nigerian-grown biomasses, gmelina (Gmelina arborea) and bamboo (Bambusaa vulgaris) hav... more Two common Nigerian-grown biomasses, gmelina (Gmelina arborea) and bamboo (Bambusaa vulgaris) have been pulped and their fibre characteristics and paper properties examined. The results of their chemical compositions showed some fair similarities. The amount of glucose in the pulps of both biomasses indicated their suitability as lignocellulosic materials for pulping. Their pulp yield ranged between 48,0-54,1%, which fell within the acceptable range for good pulpwoods. The analysis of their fibre dimensions revealed that bamboo fibre has a wider fibre length distribution and higher fine length content. Gmelina and bamboo had weighted mean fibre lengths of 0,93 and 2,07 mm and mean fibre widths of 24,1 and 16,9 µm, respectively. The Runkel ratios of the samples were 0,4 (gmelina) and 0,9 (bamboo): this is indicative of their suitability for paper making. Mechanical properties of handsheets obtained from gmelina compared fairly well with South African pulpwoods (Eucalyptus grandis and Pinus paluta). Bamboo exhibited better tear index values than these woods but with lower sheet density and tensile index. These properties were significantly improved in handsheets obtained from blends of gmelina and bamboo, raising the prospect of producing paper from blends of both raw materials in Nigeria.