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Chauhan V.S.,Indian Institute of Technology Roorkee | Bhardwaj N.K.,Thapar Center for Industrial Research and Development
Nordic Pulp and Paper Research Journal | Year: 2013

The inorganic fillers added to the paper interfere in the inter-fibre bonding and decrease the paper strength. They could not be added beyond a certain limit due to decreased paper strength and machine runnability. The talc filler was preflocculated using different doses (0.1 to 0.8%) of commercial amphoteric starch. The cooked amphoteric starch was added to talc slurry under controlled conditions. The preflocculated talcs were added to the bleached mixed hardwood kraft pulp to produce the laboratory handsheets targeting the varying ash content (15 to 24%). The particle size distribution, micro images and colloidal charge of the preflocculated talcs were measured and compared with the native talc. The filler retention, tensile, burst, tear, Z-direction tensile strength, bending stiffness, air permeability, scattering coefficient, opacity and brightness of sheets made using preflocculated talcs were compared to those of native talc. The particle size of preflocculated talc was increased up to 174%. Relatively higher filler retention and paper strength, and comparable opacity were obtained with amphoteric starch preflocculated talc compared to the native talc. SEM images of the sheets were also taken to understand the distribution pattern of preflocculated and native talcs within the sheet. Source


Karn S.K.,Thapar University | Chakrabarti S.K.,Thapar Center for Industrial Research and Development | Reddy M.S.,Thapar University
Biodegradation | Year: 2011

A pentachlorophenol (PCP) degrading bacterium was isolated and characterized from sludge of pulp and paper mill. This isolate used PCP as its sole source of carbon and energy and was capable of degrading this compound, as indicated by stoichiometric release of chloride and biomass formation. Based on morphology, biochemical tests, and 16S rRNA gene sequence analysis this strain was identified as Kocuria sp. CL2. High Performance Liquid Chromatography (HPLC) analysis revealed that this strain was able to degrade PCP up to a concentration of 600 mg/l. This is first time we are reporting the degradation of PCP by the Kocuria species. This isolate was also able to remove 58.64% of PCP from the sludge within two weeks. This study showed that the removal efficiency of PCP by CL2 was found to be very effective and can be used in degradation of PCP containing pulp paper mill waste in the environment. © 2010 Springer Science+Business Media B.V. Source


Chauhan V.S.,Indian Institute of Technology Roorkee | Bhardwaj N.K.,Indian Institute of Technology Roorkee | Chakrabarti S.K.,Thapar Center for Industrial Research and Development
Canadian Journal of Chemical Engineering | Year: 2013

Fillers are essential component of printing papers to increase the opacity, brightness, and to improve formation and printing properties. As a very little work has been reported so far on magnesium silicate (talc), the study was conducted with the filler of different particle size for papermaking. The sheets were made in the laboratory with refined mixed hardwood chemical pulp with five grades of talc, ground calcium carbonate (GCC) and precipitated calcium carbonate (PCC) fillers with 15-24% ash level. Apparent density along with tensile, burst, tear index, Z-direction tensile strength (ZDTS) and bending stiffness index were evaluated for talc filled sheets, and compared with GCC and PCC. Physical strength properties of talc filled sheets were decreased at a faster rate on increasing filler loading in paper and decreasing the particle size of the filler. With same type of filler its particle size determines the physical properties of paper. The postulate was not found to be valid for all the three varieties of fillers viz., talc, PCC and GCC. Shape and geometry of the PCC and GCC fillers determine the individual property. © 2012 Canadian Society for Chemical Engineering. Source


Karn S.K.,Thapar University | Chakrabarty S.K.,Thapar Center for Industrial Research and Development | Reddy M.S.,Thapar University
Journal of Environmental Sciences | Year: 2010

A pentachlorophenol (PCP) mineralizing bacterium was isolated from the secondary sludge of pulp and paper mill and identifi as Pseudomonas stutzeri strain CL7. This isolate used PCP as its sole source of carbon and energy and was capable of degrading th compound as indicated by stoichiometric release of chloride and biomass formation. P. stutzeri (CL7) was able to mineralize a hi concentration of PCP (600 mg/L) than any previously reported Pseudomonad with PCP as sole carbon source. As the concentrati of PCP increased from 50 to 600 mg/L, the reduction in the cell growth was observed and the PCP degradation was more than 90 in all studied concentrations. This isolate was able to remove 66.8% of PCP from the secondary sludge of pulp and paper mill wh supplemented with 100 mg/L of PCP and grown for two weeks. This study showed that the removal efficiency of PCP by CL7 w found to be very effective and can be used in PCP remediation of pulp paper mill waste in the environment. © 2010 The Research Centre for Eco-Environmental Sciences, Chinese Academy of Sciences. Source


Karn S.K.,Thapar University | Chakrabarty S.K.,Thapar Center for Industrial Research and Development | Sudhakara Reddy M.,Thapar University
International Biodeterioration and Biodegradation | Year: 2010

Pentachlorophenol (PCP) degrading Bacillus strains CL3, CL5, and CL11 were isolated from the secondary sludge of a pulp paper mill and characterized. These isolates were identified as Bacillus megaterium, Bacillus pumilus, and Bacillus thuringensis based on their 16S rRNA sequence analysis. These isolates were able to grow and utilize PCP as a carbon and energy source. HPLC analysis and stoichiometric release of chloride in the medium confirmed the degradation ability of these isolates. The removal efficiency of PCP by these bacterial isolates was highly significant and they were able to degrade more than 90% of PCP when grown at high concentration of PCP (600mgl-1). Consortia of these isolates removed 77% of PCP from the sludge. The removal efficiency of PCP by the bacterial isolate used in this study was found to be more efficient than what has been reported with other Bacillus species. These results suggest that the bacterial isolates are very effective PCP degraders and can be used in remediation of PCP-contaminated sites. © 2010 Elsevier Ltd. Source

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