【作者】 王哲；

【导师】 李忠正；

【作者基本信息】 南京林业大学 ， 制浆造纸工程， 2008， 博士

【摘要】 系统研究了麦草亚硫酸铵法制浆废液的固氮技术及超滤技术提取高分子木质素的工艺和木质素的化学结构与物化性能之间的规律性,找到了合适的处理和应用该废液的技术及其规律性。对废液固氮技术的研究解决了氨挥发对环境的污染问题,并提高了缓释氮肥中铵态氮含量。适宜的甲醛用量为10%,此时,残余亚铵已耗尽,游离氨基本固定,反应后的pH值为6.0-6.5。固氮前后的磺酸基分别为1.474 mmol·g^-1和1.918 mmol·g^-1,增加的磺酸铵为30.12%,其中木质素磺酸铵占87.4%。同时表明,温度对固氮规律影响不明显。研究了超滤技术处理麦草亚铵法废液过程中的规律,给出了超滤膜的选择、温度、操作压力等操作参数对超滤过程的影响。研究表明:截留分子量为10kDa的超滤膜较适合于分离此废液,并具有较好的抗污染性;在操作压力200kPa、温度为25℃下进行超滤,随着体积浓缩倍数的增加,灰分的透过率增加,截留液被浓缩。对超滤处理前后的废液进行了物化性能的对比研究表明:超滤后截留液中的木质素高分子量部分比例增加;截留液中的主要官能团—磺酸基、羧基和酚羟基的含量均比废液中的高;组成与结构上的变化对物化性能的影响表现在:截留液在1%水溶液中的表面张力为54.7 mN/m,较原液下降了2.2mN/m;净浆流动度提高了45.7%,即通过超滤能增强废液的应用性能。采用超滤法处理该废液时可以得到不同纯度木质素溶液样品,随着超滤时间的延长,木质素的含量从31.96%提高到68.67%;而灰分含量从23.10%下降到6.25%;糖类物质从45.52%下降到25.08%;超滤使截留液中木质素高分子量部分所占比例增加;截留液中的磺酸基、羧基和酚羟基的含量也都增加,但随着超滤的进一步进行,各基团含量的变化趋势都是先升高后降低;各样品都能降低水的表面张力,并且超滤后截留液的表面张力较原液有所降低;不同纯度木质素截留液对水泥的净浆流动度是原液的1.5倍;各样品都对二氧化钛-水体系有一定的分散能力,随着样品的加入量的增加,对二氧化钛的分散作用提高,除原液外,各截留液的用量达到1.0%时,对二氧化钛-水体系的分散作用稳定,不再增加。废液中木质素分子量对废液的应用性能有很重要的影响。论文讨论了几种改性方法对木质素的分子量分布和性能的影响。氧化反应同时发生了氧化降解和氧化缩合反应,羟甲基化反应过程中也发生了缩合反应,尤其活性基团含量高时缩合反应也越剧烈;氧化反应能提高木质素作为表面活性剂的表面活性,木质素改性用于制备表面活性剂时氧化反应较适合;有适当的相对分子质量是木质素磺酸盐减水剂的必要条件,发现羟甲基化改性效果明显,对水泥的净浆流动度提高幅度较大;但在利用氧化反应制备木素磺酸盐的减水剂时,要控制氧化反应的条件,使它主要以缩合反应为主。通过对磺化度和分子量综合研究发现,提高磺化度和分子量都能提高对水泥的净浆流动度,但在一定的磺酸基含量下,提高分子量对物化性能的影响更大。研究了亚硫酸铵法废液与Fe²⁺的氧化螯合反应及其结构特性。研究表明:木质素磺酸铵较适宜的螯合条件是:pH值3,H₂O₂用量10%,FeSO₄用量40.93%,反应温度50℃,反应时间30 min,此时对Fe²⁺的螯合率为15.08%,此螯合物在碱性条件下不生成Fe（OH）₃沉淀。同时研究了在螯合反应过程中,不同H₂O₂用量对木质素磺酸铵结构特性的影响。发现氧化后木质素磺酸铵中能与金属离子螯合的羧基、酚羟基和共轭羰基的含量增加,因此,木质素磺酸铵对Fe²⁺的螯合能力增强。此外,还发现氧化后木质素磺酸铵高分子量部分比例增加,说明在氧化过程中发生了氧化降解和氧化缩合等反应,但以氧化缩合为主,说明木质素分子量的增加也有利于木质素磺酸铵螯合能力的提高。更多还原

【Abstract】 Nitrogen fixation of the ammonia sulfite pulping spent liquor of wheat straw by using formaldehyde and the amount of ammonium lignosulfonate increased by nitrogen fixation were introduced.The results showed:formaldehyde could make the ammonium fixed in the spent liquor and the ammonium nitrogen transformed into organic nitrogen,so the spent liquor had better developmental prospect as slow release nitrogen fertilizer.The appropriate amount of formaldehyde was 10%,at this time,the residual ammonium sulfite was used up and free ammonia was basically fixed.When the reaction ended up,the pH of the spent liquor was 6.0-6.5. In order to understand the amount of ammonium lignosulfonate by the nitrogen fixation,the amount of ammonium sulfonate before and after nitrogen fixation was investigated.Experimental results indicated that the amount of ammonium sulfonate before and after nitrogen fixation was 1.474 mmol·g^-1and 1.918 mmol·g^-1,respectively.As a result,ammonium sulfonate incresed by 30.12%,in which ammonium lignosulfonate was 87.4%and Carboxymethyl ammonium sulfonate was 12.6%.Meanwhile,we found that the influence of temperature on nitrogen fixation was not obvious.The ammonia sulfite pulping spent liquor of wheat straw by ultrafiltration was introduced. In the ultrafiltration process,the effect of membrane with different cut-offs,temperature,pressure and volume concentration were researched.Experimental results indicated that the membrane with a cut-off of 10kDa was suitable for concentrating wheat straw spent liquor and had good anti-fouling property against the spent liquor.Under the operating pressure 200 kPa,temperature 25℃,following the increasing of the volume reduction,the permeability of ash was higher and the retentate was concentrated as the volume reducing during ultrafiltration of spent liquor. Ultrafiltration treatment of the ammonia sulfite pulping spent liquor of wheat straw and its influence on chemical structure characteristics and physical properties were studied.The results showed:after ultrafiltration,the molecular weight of lignin in retentate was higher than spent liquor;the content of sulfogroup,carboxyl,phenolic hydroxyl groups which are the main functional groups in retentate were all more than that in spent liquor.Meanwhile,after ultrafiltration,the retentate had better performance than spent liquor as surfactant,as additive in concrete and as dispersant,in which compared with spent liquor,surface tension at 1wt%was 54.7 mN/m,dropped 2.2 mN/m;Clean solution’s fluidity improved from 70mm to 102mm.In the spent liquor,the lignin molecular weight had a very important influence to its application performance.The influence of several modified methods to the lignin molecular weight distribution and the performance were discussed.The results indicated that oxidation-degradation and oxidation-condensation took place at the same time in the process of the oxidation,The condensation reaction took place in the hydroxyl methylolation,and the higher active group contents had higher responding activeness.The oxidized reaction could enhance the surface activity of lignosulfonate as surfactant,higher molecular weight was the dominating factors influencing the increase of dispersing and strengthening performance of lignosulfonate as additive in concrete and as dispersant.In the lignosulfonate products after hydroxyl methylolation,clean solution’s fluidity improved greatly.But when the major reaction was oxidation-condensation,oxidation reaction was advantageous as additive in concrete and as dispersant.In addition,higher molecular weight and higher sulfonic group content were the dominating factors influencing the increase of dispersing and strengthening performance of lignosulfonate,but under suitable sulfonic group content,the influence of improving the molecular weight to strengthen performance became much bigger.The chelating reaction and structure properties of ammonium lignosulfonate with Fe²⁺by oxidation were introduced.Experimental results indicated that the suitable chelating reaction condition of ammonium lignosulfonate and Fe²⁺was determined as follows:the pH was 3,the amount of hydrogen peroxide was 10%,the dosage of FeSO₄ was 40.93%,and the reaction was 50℃for 30 min.Under this reaction condition,the chelating rate of Fe²⁺was 15.08%,and the chelating compound of ammonium lignosulfonate with Fe²⁺was stable and no Fe（OH）₃ pricipitation in alkaline water solution.At the same time,The effects of the amount of hydrogen peroxide in the chelating reaction on structure properties of ammonium lignosulfonate were investigated.It was shown that the amount of phenolic Carboxyl group,hydroxyl group and carbonyl group in the chelating compound of oxidized ammonium lignosulfonate which could enhence the chelating performance of ammonium lignosulfonate was more than that of the no-oxidized ammonium lignosulfonate.As a result,the oxidized ammonium lignosulfonate had higher chelating efficiency than that of the no-oxidized ammonium lignosulfonate.In addition, the molecular weight of the oxidized ammonium lignosulfonate more than 4950 was higher than that of the no-oxidized ammonium lignosulfonate by Gel Chromatography.It was found that degradation and condensation took place at the same time in the process of the oxidation,but the major reaction was oxidation-condensation under the reaction condition.更多还原