Study On The Application Of Lipase And Xylanase In The Deinking

At present, China’s paper industry is facing a shortage of raw materials, severe energyshortages and pollution of the three main issues,Secondary fiber has been widely concernedand studied for the advantage of energy conservation and environment protection. Waste paper-one kind of secondary fiber, as a partial substitute of primary fiber, has been recycled andapplied in the industry and daily life. Deinking is one of the key steps for the retrieval of wastepaper. Traditional deinking method by chemicals has been effectively used, but it easilydestroyed fibers causing a low yield of fiber and some defects in the paper properties, as wellas severe water pollution.Because enzymatic deinking has good deinking effect,higheryield,better paper performances and less water pollution, and then promote the deinking agentused in deinking plants.so received widespread attention.The effectiveness of alkaline lipases ARL and xylanase-S7developed in our lab to oldnewspaper (ONP) deinking was firstly respectively investigated. Paper concentration on ofenzyme dosage, pulping time, flotation time and other parameters that can influence itsdeinking effect were optimized to determine the optimum conditions of ARL and S7,according to the experimental data, one lipase-ARL with higher activity and highereffectiveness was found out.ARL was mixed with xylanase-S7be a compound enzyme. The compound enzyme wasget through determining the ratio of ARL/S7and deinking aid. The effectiveness of ARL/S7on deinking was expected to be better than that by the pure lipases and S7. The compoundenzyme was experimented for waste paper deinking eincluding ONP, book/magazine, laserprinting paper compared with other two commercial enzymes (LWK and SKH) and chemicaldeinking.The result showed that deinking ability of ARL/S7was much more obvious than LWKand SKH. The deinking effects (brightness, ERIC, yield and COD et al.) after ARL/S7treatmentbasically achieved or even exceeded that by chemical deinking for different waste materialswith different ARL/S7ratios.The compound enzyme was experimented by simulating the corresponding productionprocess of three plants.ARL was mixed with S7in deinking of wastepaper includingbook/magazine and food packaging paper. The result found that the deinking effect (brightness,effective residual ink concentration, the physical properties of paper) close to or better than thefactory chemical deinking effect; ARL was mixed with S7in deinking of wastepaper includingbook/offset paper. The results show that there is a synergistic effect between ARL/S7and chemical deinking agent. Achieving the deinking effect that factory requires, the dosage ofsodium hydroxide and sodium silicate was reduced70%e and the dosage of hydrogen peroxidewas reduced50%.It significantly reduces the cost of production and the subsequent cost ofwastewater treatment.