A preliminary investigation of Nigerian Gmelina arborea and Bambusa vulgaris for pulp and paper production

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 bothbiomasses 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 densityand 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 inNigeria

Pyrolysis oil composition and catalytic activity estimated by cumulative mass analysis using Py-GC/MS EGA-MS

Please read abstract in the article.The Paper Manufacturers Association of South Africa (PAMSA)http://www.elsevier.com/locate/energy2021-11-28hj2021Chemical Engineerin

Dissolution of South African <i>Eucalyptus</i> Sawdust Wood in [Emim][OAc]/Co-Solvent Mixtures

166-172The paper presents a method of obtaining wood cellulose by dissolution of eucalyptus sawdust in a mixture of ionic liquid (IL) 1-ethyl-3-methylimidazolium acetate [Emim][OAc] together with co-solvents; dimethylformamide (DMF) and dimethylsulphoxide (DMSO), as a potential alternative to traditional non-ecological processes involving the use of volatile organic solvents or harsh chemicals. The results showed that a fraction of the wood sawdust dissolved in the mixture of [Emim][OAc] and co-solvents, and cellulose precipitated from the mixture after addition of a water /acetone mixture. The yields for the cellulose precipitates were 32.5, 17.8 % and 7.2 % for the [Emim][OAc]/DMF mixture, [Emim][OAc]/DMSO and neat [Emim][OAc], respectively. Analysis of the cellulose precipitates by FTIR spectroscopy confirmed the presence of the dominant amorphous cellulose II anomer in the regenerated cellulose. The changes in the crystalline structure of the regenerated cellulose was confirmed by comparing the XRD analytical data of the untreated sawdust wood with that of the of the regenerated cellulose samples: and it was found that the cellulose structure transformed from crystalline to amorphous after dissolution and regeneration. Scanning electron microscopy indicated that the surface morphology of the regenerated cellulose samples exhibited a structure that was rather loose, disordered and curly: this was probably due to removal of lignin and decrease in cellulose crystallinity

Screening for cellulases and preliminary optimisation of glucose tolerant β-glucosidase production and characterisation

ABSTRACTThe search for a novel microbial producer of cellulases including a glucose tolerant β-glucosidase is a challenge as most are inhibited by their product glucose. This study aims to screen for cellulolytic fungi using qualitative and quantitative screening methods. Primary screening revealed 34 of 46 fungal isolates with β-glucosidase activity. Eleven and 13 of these also displayed endoglucanase and exoglucanase activities, respectively. During secondary screening, this number was reduced to 26 β-glucosidase producers with 13 also having endoglucanase and exoglucanase activities. Isolate C1 displayed enhanced production of β-glucosidases in the presence of 0.05 M glucose (69% higher activity). Optimisation of growth conditions for β-glucosidase production by one variable at a time experiments improved production for (isolates) PS1 (64%), MB5 (84%), and C2 (69%). Isolate PS1 identified as Chaetomella sp. BBA70074 displayed the highest tolerance to glucose, retaining 10% of β-glucosidase activity in the presence of 0.8 M glucose. Tolerance to glucose increased to 14% when produced under optimal conditions. β-Glucosidase had a molecular weight of 170 kDa with a pH and temperature optima of 6 and 70°C, respectively. Future studies will include optimisation of the production of the glucose tolerant enzyme by Chaetomella sp. BBA70074

Stirred cell ultrafiltration of lignin from black liquor generated from South African kraft mills

Ultrafiltration of lignin from black liquor was carried out in a stirred batch cell using polyethersulfone membranes. Parameters such as operating pressure, feed concentration, stirring rate and membrane cut-off size were varied and their effects on lignin retention and permeate flux were investigated. The operating pressure, feed concentration and stirring rate were varied in the ranges 150–350 kPa, 3–9% and 200–400 rpm, respectively. The membranes used had cut-off sizes of 5 kDa, 10 kDa and 20 kDa. A one-factor-at-a-time experimental design approach was applied in this study. Retention of lignin increased with increases in operating pressure, feed concentration and stirring rate, but decreased with an increase in molecular cut-off size of the membrane. Permeate flux on the other hand increased with increases in pressure, stirring rate and molecular cut-off size of the membrane but decreased with an increase in feed concentration. The extraction of lignin from black liquor was successfully carried out and extraction efficiencies as high as 86% could be achieved depending on the experimental conditions. The study was concluded with the recommendation of conducting additional experiments using a pilot plant in a continuous mode. Significance:&nbsp; The extraction of lignin from black liquor was successfully carried out and extraction efficiencies as high as 86% were obtained. The results can be used to extend the ultrafiltration of black liquor to an industrial scale

Classification of Lipolytic Enzymes and their Biotechnological Applications in the Pulping Industry

In the pulp and paper industry, during the manufacturing process the agglomeration of pitch particles (composed of triglycerides, fatty acids and esters) leads to the formation of black pitch deposits in the pulp and on machinery which impacts on the process and pulp quality. Traditional methods of pitch prevention and treatment are no longer feasible due to environmental impact and cost. Consequently, there is a need for more efficient and environmentally friendly approaches. The application of lipolytic enzymes such as lipases and esterases could be the sustainable solution to this problem. Therefore, an understanding of their structure, mechanism and sources are essential. The microbial sources for the different groups of lipolytic enzymes, differences between lipases and esterases and their potential applications in the pulping industry are reviewed here.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Optimisation of <i>β</i>-Glucosidase Production in a Crude <i>Aspergillus japonicus</i> VIT-SB1 Cellulase Cocktail Using One Variable at a Time and Statistical Methods and its Application in Cellulose Hydrolysis

Pulp and paper mill sludge (PPMS) is currently disposed of into landfills which are reaching their maximum capacity. Valorisation of PPMS by enzymatic hydrolysis using cellulases is an alternative strategy. Existing commercial cellulases are expensive and contain low titres of β-glucosidases. In this study, β-glucosidase production was optimised by Aspergillus japonicus VIT-SB1 to obtain higher β-glucosidase titres using the One Variable at a Time (OVAT), Plackett Burman (PBD), and Box Behnken design (BBD)of experiments and the efficiency of the optimised cellulase cocktail to hydrolyse cellulose was tested. β-Glucosidase production was enhanced from 0.4 to 10.13 U/mL, representing a 25.3-fold increase in production levels after optimisation. The optimal BBD production conditions were 6 days of fermentation at 20 °C, 125 rpm, 1.75% soy peptone, and 1.25% wheat bran in (pH 6.0) buffer. The optimal pH for β-glucosidase activity in the crude cellulase cocktail was (pH 5.0) at 50 °C. Optimal cellulose hydrolysis using the crude cellulase cocktail occurred at longer incubation times, and higher substrate loads and enzyme doses. Cellulose hydrolysis with the A. japonicus VIT-SB1 cellulase cocktail and commercial cellulase cocktails resulted in glucose yields of 15.12 and 12.33 µmol/mL glucose, respectively. Supplementation of the commercial cellulase cocktail with 0.25 U/mg of β-glucosidase resulted in a 19.8% increase in glucose yield

Empowering communities in Zimbabwe - new configurations of power

Moves to empowering communities are now widespread in Zimbabwe. In this paper what happens to the locus of power during empowerment is discussed by drawing on case study material from three areas: Gokwe, Chivi, and Sengwe/Chikwarakwara. These areas differ in the types of resources that are important and the stakeholders involved. In Gokwe and Sengwe/Chikwarakwara the high value timber and wildlife resources, respectively, are dealt with by the rural district council (RDC) and the private entrepreneurs. Empowerment in these cases has meant rise in power of the RDC, and there are numerous examples of where the RDC is in conflict with local people. With lower value resources, the entrepreneurs are more likely to be community members, and any power struggles take place at the local level, highlighting the differences among rich and poor, traditional and modern local structures, etc. The cases illustrate that the concept of ‘community-based’ is extraordinarily difficult to achieve