Study On Hydrogen Peroxide Alkaline Pulping Of Bagasse

One of the largest cellulosic agro-industrial by-products is sugar cane bagasse,a fibrous residue of cane stalks left over after the crushing and extraction of the juice from the sugar cane.Bagasse consists of cellulose 32%⁴8%,lignin 23%³2%,hemicellulose 19%²4%,protein 2%,ash 1%.The ash content of bagasse is lower than that of wheat straw and straw,which is beneficial to the recovery of alkali in black liquor.Bagasse is used for each of the four main paper categories,namely packaging and boxes,printing,writing and photocopier paper,tissues,and newsprint.Both chemical and mechanical pulping processes are used,soda and soda anthraquinone?AQ?pulping are commonly used processes for producing bagasse chemical pulp.Pulp yield is typically in the range 48–55%,most of the silicon dissolved in black liquid,black liquor having high viscosity and to cause significant problems with fouling,alkali recovery lower.Pulp and paper industry has been constantly exploring and seeking for high yield pulp production methods that can save raw materials and investment,reduce production costs and reduce environmental pollution.Alkaline hydrogen peroxide pulping is a kind of pulping method with low cost and high yield.The effects of major cooking variables on the hydrogen peroxide alkaline?PA?pulping of bagasse were investigated.The PA pulping can be performed at lower cooking temperature,but moderate amounts of AQ cooking additive should be added to the process,and the time at the cooking temperature also should be prolonged.The better pulping results have been achieved under following conditions:hydrogen peroxide of 2%,AQ of 0.1%,the cooking temperature of130?,time at the cooking temperature of 90 min.Compared with traditional Soda AQ pulping,the PA AQ pulping yield was significantly improved,Kappa number of the brown pulp was decreased,and the pulp brightness was increased.The PA AQ pulp had lower tear index,and the similar tensile index and burst index.The pre-extraction of hemicellulose from bagasse before pulping was studied in this paper.The hydrogen peroxide alkaline pulping properties of bagasse which had been pre-extraced with alkali were studied.The properties of hydrogen peroxide alkaline pulp were emphatically investigated.The experiment results show that:Some hemicellulose,ash and acid-soluble lignin can be extracted by alkali extraction at a certain concentration before cooking,which improves the possibility of alkali recovery from black liquor and reduces the consumption of alkali and hydrogen peroxide in subsequent cooking process.The best alkaline pretreatment conditions were:NaOH 40 g/L,temperature at 25?and extraction time of 1 h,At this conditions before hydrogen peroxide alkaline pulping,the main properties of the pulp were:kappa number 7.19,pulp viscosity 16.85 mPa·s,pulp yield 57.02%and brightness 47.17%ISO.Compared with the pulp without extraction,kappa number decreased by 9.8%.While for the paper,tensile index,tear index and brust index were 85.32 N·m/g,3.01 mN·m²/g and 4.43 kPa·m²/g.Compared with the pulp without extraction,the tensile index and burst index increased by 8.04%and7.79%.The alkaline hydrogen peroxide mechanical pulp of bagasse were studied.Fistly,the effects of the amount of alkali,hydrogen peroxide,temperature and soaking time on the yield and components of pulp were analyzed.Then,the optimum process conditions are explored.The result indicates that the optimum condition of alkaline hydrogen peroxide mechanical pulp of bagasse:NaOH 8%,H₂O₂ 1%,temperature at 110?and soaking time of 1 h.Compared with the waste pulp,the strength property of the bagasse pulp under this condition achieved the ideal result.