COMPARISON OF ECF-LIGHT,TCF AND CEH BLEACHING OF NON-WOOD FIBRES

A comparative evaluation of DQP, OQP and CEH bleaching of non-wood fibres has revealed that wheat straw, reed, bagasse and bamboo pulps can be bleached to brightness levels of just above 80% ISO, when applying an OQP bleaching sequence and to brightness levels of about 85% ISO when applying the DQP sequence using 10 - 15 kg/tp of ClO2 (aCl.), 15 - 20 kg/tp of H2O2 together with 1 - 2 kg/tp of EDTA. The P.C. numbers of the DQP and OQP bleached pulps are much lower and the viscosity much higher than those of the CEH bleached pulps. Compared with CEH pulps, both the DQP and OQP pulps had better strength properties, particularly Tear Index. In spite of their higher final brightness levels, the DQP pulps show similar or better strength properties than the OQP pulps. A comparison of the CEH and DQP effluents showed that the DQP bleaching could reduce the pollution load (CODCr, BOD5, SS) by 35 to 60% without the need for recirculation of any effluent streams. The AOX levels could be reduced by 87 to 93%.

STUDY ON THE DIGESTION PROCESS OF ASF-AQ WHEAT STRAW PULP

A study on alkaline sulfite anthraquinone pulping of wheat straw indicated that the addition of formaldehyde could improve fine pulp yield effectively, enhance brightness of unbleached pulp, and decrease kappa number. Finally, the optimum conditions of this process were formed.

APPLICATION OF CATIONIC POLYMERIC MICROPARTICLES ON RETENTION AND DRAINAGE

The conditions of preparation and performance of a new structure of cationic organic polymeric micropaticles (CPMP) mainly composed of styrene and DADMAC were studied. And its application on retention and drainage on bleached hardwood pulp was investigated and compared with that of APAM and CPAM. The results show that the retention and drainage of CPMP on pulp is in positive proportion to the rise of the potential of the solution, and the first-pass retention ratio of bleached hardwood pulp goes up with the increase of the CPMP content. The functions of CPMP and CPAM are affected less by the shear force and the pH value of the system compared to that of APAM, and effect on retention of CPMP3 is appropriate to that of CPAM, but superior to that of APAM.

WHEAT STRAW ALKALINE LIGNIN AND ITS DERIVATIVES AS RETENTION AID

In this paper, a new type of retention system of PEO/cofactor retention system is introduced, the cofactors used are phenol-formaldehyde resin, wheat straw alkaline lignin and its derivatives such as hydroxymethylated lignin, sulfited lignin and lignin-based phenol-formaldehyde resin. The first pass retention of newsprint slurry and the properties of handsheet are improved by using the system. The results indicate that a new application field for lignin has been exploited.

STUDY ON THE DECHLORINTION MECHANISMS DURING ANAEROBIC TREATMENT OF PULP BLEACHERY EFFLUENTS

Anaerobic treatment could effectively degrade organic chlorine. Reductive dechlorination mechanisms were confirmed through GC-MS analysis during anaerobic treatment of pulp bleachery effluents, the influence of sulfide biologically produced and pH on the dechlorination revealed that nucleophilic substitution and alkaline hydrolysis were also nonbiological mechanisms.

BIOCHEMICAL PULPING OF REED PRETREATED BY WHITE ROT FUNGI

The Soda-AQ pulps were made from reed pretreated by white rot fungi Panus conchatus, Cyathus stercoreus and Pleurotus florida respectively. It was found that kappa number decreased and the brightness increased for Soda-AQ pulps from the reed treated by Pleurotus florida and Panus conchatus, but it was reverse for the pulp from reed treated by Cyathus stercoreus. The result indicated that white rot fungi Pleurotus florida and Panus conchatus were selective to degrade lignin in reed, which were good for biopulping, but Cyathus stercoreus was preferential to degrade cellulose, which was not good for biopulping.

THE INDUSTRIAL UTILIZATION OF CHEMICAL MODIFIED AGRICULTURAL RESIDUES

Various lignocellulosic materials such as wood, agricultural and forest residues has the potential to be valuable substitute for, or complement to, commercial sorbents for removing heavy metal ions or dyes from waste water or spilled oil from inland water or sea. More than 9 million tons of straw pulp are produced annually in china, which account for about 90% of the world’s total straw pulp. However, huge quantity of remain straw is not used as industrial raw material and is burnt in the fields or on the side of road. These resources can be chemical modified such as acetylation. Modified straws have the characteristics of low cost, high capacity, quick uptake, and easy to desorb. This paper reviews the current status of the technology for modified agricultural residues, which focus on hemicellulose and cellulose. The potential of these natural sorbents in main industry is also indicated.

P-RC APMP PULPING OF THE TRIPLOID OF POPULUS TOMENTOSA

The technology parameters of P-RC APMP process of the triploid of populus tomentosa and the comparison of P-RC APMP with one and two stage of pretreatment were investigated in this paper. The results showed that in the chemical pretreatment the charge of NaOH and H2O2 were the main factors that affected the pulp qualities. The charge of NaOH, especially in the first stage of chemical pretreatment, was related to pulp strength. The charge of H2O2 contributed much to brightness of the resultant pulp. In addition, the ratio of NaOH to H2O2 and the distribution of chemicals in the first and second stage of impregnation also affected the pulp qualities. The comparison of one-stage P-RC APMP pulp and two-stage P-RC APMP pulp illustrated that the two-stage pulp had better brightness and breaking length, lower light scatting coefficient and

POLYETHER POLYURETHANE FROM MODIFIED WHEAT STRAW OXYGEN-ALKALINE LIGNIN

Polyether polyurethane was synthesized from modified wheat straw oxygen-alkaline lignin, polyethylene glycol and two different diisocyanates (diphenylemethane-4, 4’-diisocyanate, tolulene diisocyanate) by solution casting method, its properties were investigated. The results show that modified wheat straw oxygen-alkaline lignin can substitute part of polyethylene glycol to react with diisocyanate to synthesize polyurethane. The molar ratio of NCO to OH and modified wheat straw oxygen-alkaline lignin content affect the properties of lignin-based polyether polyurethane respectively. The addition of plasticizer in the polyurethane synthesis process improves the properties of synthesized polyurethane, especially the elasticity of polyurethane. The synthesized polyurethane from modified wheat straw oxygen-alkali lignin can be used as both engineering plastic and hard foam plastic in future.

STUDY ON THE ELEMENTAL CHLORINE FREE BLEACHING OF BAMBOO KRAFT PULP

The influential factors of DQP bleaching, chlorine dioxide bleaching, chelation and hydrogen peroxide bleaching, of bamboo kraft pulp were studied. The pH value in D stage, dosage of EDTA in Q stage and charge of MgSO4 in P stage were optimized. The results indicated that good results of chlorine dioxide bleaching were obtained under the conditions of ClO2 2.0%,pH 4, and the highest final brightness(86.4%ISO) and the lowest final Kappa number(1.37) were attained when the charge of EDTA in Q stage was 0.4%, charge of MgSO4 in P stage was 0.2%, and the other conditions of P stage : pulp consistency 10%, H2O2 charge 2.5%, NaOH charge 1.4%, temperature 90℃ and time 120 min. A comparison of bleaching results, pulp strength and effluent characteristics of bamboo kraft pulp between DQP and CEH sequences was done. The results indicated that bamboo kraft pulp could be bleached to brightness of above 83%ISO by both DQP and CEH sequences. Compared with CEH bleached pulp, DQP bleached pulp had slightly lower brightness, better brightness stability, higher pulp viscosity, better strength properties and lower pollution loads.

ENZYME-ASSISTED DEINKING AND FIBER MODIFICATION OF MIXED OFFICE WASTE

Three kinds of cellulases with different components were applied to the deinking of mixed office waste paper, MOW. In the process of enzymatic deinking of MOW, not only improvement of toner particle removal was achieved with the addition of enzymes but other properties of the deinked pulps were influenced. Drainage properties of the deinked pulp were improved after treated with enzymes. Higher enzyme dosage was needed compared with that only for deinking purpose if obvious drainage improvement of the deinked pulp were to be achieved. The enzymatic hydrolysis of fibers did not lead to distinct fiber length decrease, but declined the zero tensile strength of the pulp declined with addition of enzymes, which indicating the decrease of individual fiber strength. In addition, enzyme treatment resulted in the enhancement of specific surface area of fibers.