【作者】 张春辉；

【导师】 詹怀宇；

【作者基本信息】 华南理工大学 ， 制浆造纸工程， 2008， 博士

【摘要】 在化学机械浆和脱墨浆生产过程中会有一部分物质分散在过程水或浆水体系中,称之为DCS(Dissolved and Colloidal Substances,DCS)。随着白水系统封闭循环程度的提高,DCS物质会产生积累,对制浆造纸过程和产品质量产生不利的影响。为此,对马尾松化机浆和ONP脱墨浆两种浆水体系中DCS的化学组成、释放机制、稳定性等进行了详细的研究,并探讨了生物酶对DCS的处理效果及作用机理。论文首先对马尾松化机浆和ONP脱墨浆中的DCS物质进行了定性定量分析。结果发现,马尾松化机浆DCS中的脂肪酸主要有油酸、亚油酸等,树脂酸主要有脱氢枞酸、海松酸、枞酸以及脱氢枞酸氧化物等;一段磨后浆、漂前浆、过氧化氢漂后浆DCS中脂肪酸与树脂酸的比例分别约为1:2.8、1.2:1、1:3.8。脱墨浆DCS中树脂酸占脂肪酸和树脂酸总量(RFAs)的近90%,主要是脱氢枞酸和枞酸。DCS中糖类组分的分析结果表明,马尾松化机浆DCS中的碳水化物除了聚半乳糖葡萄糖甘露糖外,还有较多的聚阿拉伯糖葡萄糖醛酸木糖和聚阿拉伯糖半乳糖。经过过氧化氢漂白后,悬浮液DCS中各糖基的浓度均增大,释放出了更多的果胶质。脱墨浆DCS中糖基主要是4-O-甲基-葡萄糖醛酸和木糖。接着对两种浆水体系中DCS的释放规律进行了研究。结果发现,木片挤压机的挤压作用对抽出物组分几乎没有选择性,基本按照原木片中抽出物的比例释放出来。第一段磨浆机出口纸浆中树脂组分不是等比例地分散到水中,枞酸的释放量仅占总RFAs的0.74%。漂前浆DCS中总脂肪酸占总RFAa的比例高达50%。这说明此条件下脂肪酸更容易从纤维中分散到水相中。pH值对漂前浆中DCS的释放影响很大。pH值超过8以后,释放出了更多的树脂组分和果胶质,导致DCS浊度的迅速增大和DS部分CD值的增大。对脱墨浆生产线不同阶段浆料DCS的分析发现,样品中总脂肪酸与总树脂酸的比例基本不变,约为1:9,但漂后浆(4~#)中各树脂酸之间的比例变化较大,由于脱氢枞酸浓度的大幅降低导致了其它树脂酸所占比例的升高。废纸在碱性碎浆过程中产生了较多的半乳糖醛酸。选用有代表性的树脂及合成聚合物模型物,研究了各模型物在金属离子、阳离子聚合物、填料等存在条件下的稳定性以及可溶性聚糖对树脂模型物稳定性的影响。结果发现,加入无机电解质后靠静电斥力而稳定存在的胶体颗粒会失去稳定性而发生聚集。中性的甘油三酯(TG)乳液的残余浊度下降最快,稳定性最差。随着CPAM加入量的增加,体系的残余浊度下降,CPAM加入到一定量时,胶态乳液会完全失稳。当CPAM加入量继续增加,胶体颗粒会重新获得稳定性。PCC和滑石粉可以吸附模型物乳液中的胶体颗粒,导致体系失去稳定性。在pH为7.0时,模型物对滑石粉的稳定性顺序为脂肪酸(O)＞树脂酸(R)＞甘油三酯(TG),对PCC的稳定性顺序为O＞TG＞R。中性聚糖(GM)对三种模型物乳液均有一定的稳定作用。随着聚糖浓度的增大,R和O乳液的稳定性均增强,且可以达到不受金属离子影响的程度。GM的存在只是阻碍/减缓了CPAM与胶体颗粒的接触,而不能抵挡阳离子聚合物对胶体颗粒的进攻。GM与滑石粉之间有一定的亲合力,在一定程度上减少了滑石粉对模型物乳液胶体颗粒的直接吸附,有利于体系的稳定。在酸性聚糖(PGA)-X(X=R,O,TG)-Na~+体系中,PGA对三种树脂模型物乳液都有一定的稳定作用,它可以增加树脂液滴的表面电荷密度。其中,对R乳液的稳定效果最好,O乳液次之,TG最差。钙离子与PGA之间不是简单的电荷中和问题,它会与胶体颗粒表面的PGA的羧基结合生成不溶物,产生共聚沉现象;如果体系中的中性聚糖足以使模型物胶粒稳定,那么酸性聚糖对体系稳定性的影响就会限制在一定范围内。探讨了树脂组分之间的相互作用对体系稳定性的影响。结果发现,乳液的制备方法不同,R,O,TG三者在体系中的相互作用也不同。各自配成乳液再进行混合时(即方案1),在pH为5.0条件下,三者乳液不存在相互作用;但加入钙离子以后,三者在失稳的过程中有一定的相互作用。各模型物的无水乙醇溶液先按比例进行混合再制得相应的乳液时(即方案2),在pH 5.0和7.0条件下,混合物乳液的浊度都不与模型物的比例存在线性关系。在模型物O的比例较小时,R与TG之间存在较强的作用;而在R的比例较小时,O与TG之间有一定的作用,但不及R与TG之间的作用强。在TG浓度较低时,R与O之间也有相互作用,但结果使得体系的浊度低于理论值。组分之间的相互作用使得体系中的胶体颗粒不是单一组分,而是由模型物(R,O,TG)混和物形成的。在pH5.0时,各模型物的无水乙醇溶液先按比例进行混合再制得相应的乳液时(即方案2)制得的混合物乳液中加入钙离子以后,体系的残余浊度基本上与模型物的比例呈线性关系,进一步证实了多组分胶体颗粒模型。在pH 7.0时,模型物两两之间的作用对体系的稳定性是不利的,特别是在TG比例较高时,这种影响更为明显。最后探讨了脂肪酶、果胶酶和漆酶对模型物及DCS物质的处理效果及其作用机理。果胶酸(盐)裂解酶(PGL)降解果胶酸模型物较优的条件为pH 9.0,温度60℃,120min。PGL可以有效地降解脱墨浆和马尾松漂白化机浆DCS中的果胶酸,DCS的CD值下降了约40%。果胶酸类物质只有其平均聚合度超过6时,才会与阳离子聚合物发生较强的反应,降低其使用效率。碱性果胶酶PL可以有效地酶解果胶模型物,当用量为200 U时(果胶模型物为5mg),果胶模型物的CD值下降约80%。较优的处理条件为:温度70℃,pH 9.0,120min。PL可以有效地降低马尾松漂白浆DCS的CD值,对提高DCS的稳定性作用不大,但可以减缓其沉淀的速度。在漂白浆DCS中的果胶类物质主要以果胶酸的形式存在。脂肪酶LP1和LP2可以有效地水解甘油三酯,LP1较优的使用条件为:pH 7.0,温度70℃;LP1较优的使用条件为:pH 6.0,温度60℃。它们可以从甘油的三个位置上释出脂肪酸,最终得到甘油和游离脂肪酸。脂肪酸的存在会抑制脂肪酶的活力。漆酶在ABTS(2,2-连氮-二(3-乙基苯并噻唑-6-磺酸))或紫尿酸存在的条件下可以降解带有共轭双键的树脂酸和不饱和脂肪酸;在不加介体的情况下漆酶处理可以除去马尾松CTMP的DCS样品中的部分长叶松酸和枞酸。更多还原

【Abstract】 During the production of chemi-mechanical pulp and deinked pulp,dissolved and colloidal substances(DCS) are released from the fibers into the process waters or pulp-water systems.The white water systems are increasingly closed,which results in the accumulation of DCS in the water systems.The increased amounts of DCS will affect the pulp and papermaking processes and the paper quality.Thus,the composition,release mechanisms and stability of DCS from Masson pine CTMP(chemi-thermo-mechanical pulp) and ONP (old newsprint) deinked pulps were studied in detail.Additionally,The efficiency and mechanisms of enzymes to treat DCS were investigated.Firstly,the components of DCS from Masson pine CTMP and ONP deinked pulps were analyzed qualitatively and quantitatively.Results showed that the RFAs(resin and fatty acids) in DCS of Masson pine CTMP were mainly composed of oleic acid,linoleic acid,DHA (dehydroabietic acid),pimaric acid,abietic acid and oxidized products of DHA.The ratio of fatty acids to resin acids in FR-DCS(DCS of the first refiner pulps),CTMP-DCS(DCS of unbleached CTMP),BCTMP-DCS(DCS of peroxide bleached pulps) were 1:2.8,1:2.1 and 1:3.8,respectively.About 90%of RFAs in DCS of deinked pulps were resin acids,among which DHA and abietic acid were the predominant ones.Based on the proportion of sugar units determined,the carbohydrates in DCS of Masson pine CTMP contained galactoglucomannans and considerable amounts of arabinolglucoxylans and arabinogalactans.More pectic substances were released during the peroxide bleaching.The main sugar units in DCS of deinked pulps were 4-O-methyl-glucuronic acid and xylose.Secondly,the release mechanisms of DCS from Masson pine pulps and deinked pulps were investigated.It was found that screw press could extrude the wood resins from chips non-selectively.RFAs in the first refiner pulps were not dispersed into the water phase proportionally,and much smaller amount of abietic acid was released.The amount of fatty acids in CTMP-DCS was increased up to 50%of total RFAs.This indicated that fatty acids were more easily released from fibers than resin acids in that condition.The release of DCS from unbleached CTMP fibers was strongly affected by the initial pH value of the suspension. As the pH value was above 8.0,much more wood resins and pectic substance were released, leading to the increase of turbidity and CD value of DCS.The ratio of fatty acids to resin acids in DCS of deinked pulps almost remained the same at 1:9.However,the proportion of resin acids components in No.4 sample(DCS of peroxide bleached pulp) was different from those of another three samples(DCS of unbleached pulps, 1~#-3~#),with DHA being a relative minor component,due to the large decrease of DHA concentration.Then representative models of wood resins,i.e.triglyceride(TG),fatty acid(O) and resin acids(R) and synthetic polymer(PA) were selected to study the stability of resins and synthetic polymer in DCS in the presence of simple electrolytes,cationic polymer,or fillers. Furthermore,effects of polysaccharides on the stability of model emulsions under the conditions mentioned right above were investigated in detail.Results showed that metal ions (sodium ions and calcium ions) could lead to the aggregation of model emulsions stabilized by electrostatic mechanism.The residual turbidity of TG emulsion decreased rapidly upon addition of simple electrolytes,which indicated that TG was much more easily destabilized than R and O emulsions.The residual turbidity of three model emulsions(R,O,TG) decreased with the increasing dosage of CPAM(cationic polyacrylamide).At a certain dosage of CAPM,the model emulsions would be completely aggregated.If more CPAM was added,the emulsion would re-stabilize.Fillers(PCC and talc) could adsorb the colloids in the model emulsions,resulting in the aggregation/flocculation of colloids.At pH 7.0,emulsion O had the best stability against PCC-induced aggregation,with emulsion R being the worst;as for talc,emulsion O were the best with TG being the worst.Neutral polysaccharide GM had a positive effect on the stability of three model emulsions in the presence of simple electrolytes,cationic polymer,or fillers.The stability of emulsion R and O could even be enhanced to a level that metal ions could not induce the aggregation of colloids.GM could slow down/baffle the direct contact of CPAM with colloids to a certain extent,but could not keep the colloids from being attacked by CPAM. There could be an affinity between GM and the added talc particles,which affected the absorption of colloids onto the surface of talc particles.This affinity was favorable for the stability of emulsions.Acidic polysaccharide PGA had positive effect on the stability of three model emulsions (R,O,TG) against sodium-induced aggregation by increasing the surface charge density of colloids.The efficiency of stabilizing emulsion R was the highest,with TG being the lowest. Interaction between calcium ions and PGA could barely be explained by a charge neutralization mechanism.Insoluble aggregates were formed between calcium ions and the carboxyl groups of PGA,leading to a co-aggregation of colloids and the aggregates.However, once the added GM was enough to wrap the colloids,the adverse effect of PGA would be limited within a certain range.Interactions between colloids of three model emulsions and their effects on the mixture stability were investigated.The interactions between colloids depended on the preparation procedure of mixture.There were no observable interactions between colloids at pH 5.0,if pre-emulsified models were mixed together(procedure 1) without addition of calcium ions. However,some interactions might exist when the colloids were de-stabilized upon addition of calcium ions into the mixture.The mixture(procedure 2) made of pre-mixed ethanol solution of model resins and distilled water was different from that of pre-emulsified models.At both pH 5.0 and 7.0,there existed considerable interactions between components(model R,O,TG) without addition of calcium ions.Two-component interactions(R-TG,O-TG,R-O) were relatively strong as the proportion of the third component(O,R,TG) was low.R-TG and O-TG interaction contributions to the total turbidity of mixture were positive,while that of R-O interaction was negative.The absolute contribution of R-TG interaction was the largest,with that of R-O being the smallest.The interactions between components resulted in the formation of two/three-component colloids,but not a single-component ones.At pH 5.0,the residual turbidity of mixtures of procedure 2 was almost linearly correlated to the proportion of three models upon addition of calcium ions,with the interaction contributions to the turbidity being negligible.This further confirmed the structure model of two/three-component colloids.At pH 7.0,two-component interactions had adverse effect on the mixture stability against calcium-induced aggregation,especially as the proportion of TG was high.Finally,the efficiency and mechanism of two lipases and two pectinases as well as to degrade or hydrolyze model substances and DCS from Masson pine BCTMP and deinked pulps were evaluated.The optimal conditions for pectate lyase(PGL) treatment were as follows:pH 9.0,60℃,120min.PGL could effectively degrade the pectic acid in the DCS of Masson pine BCTMP and bleached DIP,resulting in a decrease of about 40 percent in CD value.A minimum average DP(degree of polymerization) of 6 was required for pectic acid to interact strongly with cationic polymers and reduce the efficiency of the latter.Alkaline pectin lyase(PL) could efficiently degrade the pectin model.A decrease of 80 percent in CD value could be achieved at a dosage of 200 U(pectin model 5 mg).The optimal conditions for PL treatment were pH 9.0,60℃,120min.PL could effectively reduce the CD value of DCS from Masson pine BCTMP.Treatment of DCS from Masson pine BCTMP with PL could not prevent DCS from complete aggregation by calcium ions,although the rate of aggregation was lower.Pectic substances in DCS of BCTMP were mainly composed of unmethylated pectic acids.Two lipases(LP1 and LP2) could effectively hydrolyze triglyceride.The optimal conditions for LP1 and LP2 treatment were pH 7.0,70℃and pH 6.0,60℃,respectively.All of three ester bonds in triglyceride could be hydrolyzed by these two lipase,with the final product of glycerol and free fatty acid.The ability of lipases to hydrolyze triglyceride was strongly affected by fatty acids added.Laccase could degrade the conjugated resin acids and unsaturated fatty acids in model emulsions(R,O,TG) to some extend in the presence of ABTS(2,2’-azinobis(3-ethylbenzthiazoline-6-sulfonate)) or VIO(violuric acid).Palustric acid and abietic acid in DCS of Masson pine CTMP could be partially removed by lacaase treatment without addition of external mediator.更多还原