【摘要】：我國(guó)是紡織工業(yè)大國(guó)，同時(shí)也是紡織品消費(fèi)大國(guó)，每年我國(guó)因此而產(chǎn)生的廢舊紡織品高達(dá)數(shù)千萬(wàn)噸之巨。如今，我國(guó)的的廢舊紡織品再資源化綜合利用才剛剛起步，因此，真正得到再資源化利用的還不足十分之一，而未能得到有效再利用的部分既造成了資源浪費(fèi)，又帶來(lái)了環(huán)保的問(wèn)題。 滌綸（polyester簡(jiǎn)稱PET）織物在廢棄的紡織品中占據(jù)了相當(dāng)大的比重，因此，如何通過(guò)合理有效的辦法使廢舊滌綸織物得以再資源化成了擺在我們眼前亟需解決的難題。近些年來(lái)，我國(guó)的滌綸產(chǎn)量一直呈現(xiàn)有增無(wú)減的態(tài)勢(shì)，2013年我國(guó)滌綸產(chǎn)量為3327.61萬(wàn)噸，占到了全球總產(chǎn)量的七成以上，但用來(lái)生產(chǎn)滌綸的初級(jí)原料對(duì)二甲苯（PX）卻嚴(yán)重依賴進(jìn)口，2013年我國(guó)對(duì)二甲苯的對(duì)外依存度高達(dá)53%，且缺口仍在不斷增加。遺憾的是，當(dāng)前消費(fèi)掉的滌綸織物幾乎全部被當(dāng)做垃圾掩埋或焚燒，綜合利用率不足1%，因此大力開發(fā)滌綸聚酯的回收再利用技術(shù)已經(jīng)成為滌綸聚酯工業(yè)發(fā)展的關(guān)鍵所在。當(dāng)今，PET再資源化利用的方法主要有酸性水解法、堿性水解法、中性水解法、甲醇醇解法以及乙二醇醇解法等，然而中性水解廢舊PET是最具有發(fā)展前景的。 本實(shí)驗(yàn)以經(jīng)過(guò)前處理的廢棄滌綸織物為原料，以亞臨界狀態(tài)下的水為 溶液，在高壓釜內(nèi)使滌綸織物降解。采用氮氮二甲基甲酰胺（DMF）剝色系統(tǒng)對(duì)廢棄的滌綸織物進(jìn)行前期的剝色處理，，討論了投料比（去離子水與滌綸布料的質(zhì)量比）、反應(yīng)溫度、保溫時(shí)間對(duì)PET降解率以及產(chǎn)物的白度、純度、酸度的影響，并對(duì)PET在亞臨界水條件下的水解機(jī)理進(jìn)行了初步摸索，揭示了聚對(duì)苯二甲酸乙二醇酯在水熱條件下的水解過(guò)程以及反應(yīng)機(jī)理，最后還對(duì)降解所得白色固體對(duì)苯二甲酸（TPA）的各項(xiàng)質(zhì)量指標(biāo)進(jìn)行了測(cè)定。 （1）本文討論明確了廢舊滌綸織物的剝色前處理主要分為溶脹劑溶脹、分散染料的剝色以及還原剝色三個(gè)過(guò)程。本文選用的溶脹劑為二甲基亞砜（DMSO），分散染料的剝色劑選為DMF，還原劑為二氧化硫脲（TDO）。確定了最佳剝色工藝條件為：剝色時(shí)間30min，剝色溫度控制在140℃。 （2）采用中性水解法回收再利用廢舊滌綸織物，再資源化產(chǎn)物為TPA和乙二醇（EG），投料比（去離子水和滌綸織物的質(zhì)量比）、反應(yīng)溫度以及保溫時(shí)間是滌綸織物水解的最主要的影響因素；明確了最佳的水解條件：投料比10:1，實(shí)驗(yàn)溫度250℃，反應(yīng)時(shí)間7h。在最佳條件下PET的降解率可以達(dá)到92.9%，TPA的產(chǎn)率為86.4%，TPA純度為98.251%，TPA的酸度可達(dá)657.14mgKOH/g。 （3）明確了PET的水解機(jī)理：在高溫高壓下水會(huì)電離成H+和OH-，H+與-COOR中的羰基作用形成C+，同時(shí)水的H進(jìn)攻-COOR中的C，形成四面體的中間產(chǎn)物。然后，水中的H離去，O上的電子發(fā)生轉(zhuǎn)移，酰氧鍵斷裂，最后降解成TPA和EG。 （4）明確了PET水解生成的TPA的各項(xiàng)質(zhì)量指標(biāo)滿足精對(duì)苯二甲酸（PTA）標(biāo)準(zhǔn)的實(shí)驗(yàn)條件：反應(yīng)溫度≥250℃，反應(yīng)時(shí)間8h，投料比10:1，干燥溫度100℃、干燥時(shí)間8h。
[Abstract]:China is a big country in textile industry and also a big country in textile consumption. The amount of waste textiles produced in our country is tens of millions of tons every year. Nowadays, the comprehensive utilization of waste textiles has just started. Therefore, less than one tenth of the waste textiles have been reused, but they have not been effectively reused. It not only caused the waste of resources, but also brought about environmental problems.
Polyester (PET) fabrics occupy a considerable proportion in the waste textiles. Therefore, how to reuse waste PET fabrics by reasonable and effective means has become a difficult problem to be solved urgently. In recent years, China's polyester production has been showing an increasing trend, in 2013 China's polyester production. The total output is 33.2761 million tons, accounting for more than 70% of the world's total output. However, the primary raw material for producing polyester fibers is heavily dependent on imports. In 2013, China's dependence on paraxylene was as high as 53%, and the gap is still increasing. Unfortunately, almost all of the polyester fabrics currently consumed were buried or burned as garbage. The comprehensive utilization rate of PET is less than 1%. Therefore, the recycling technology of PET has become the key to the development of PET industry. Nowadays, the recycling methods of PET mainly include acid hydrolysis, alkaline hydrolysis, neutral hydrolysis, methanol alcoholysis and ethylene glycol hydrolysis. It is the most promising one.
In this experiment, the waste polyester fabric treated before is used as raw material, and the water in subcritical state is used as the raw material.
Polyester fabric was degraded by solution in autoclave. The waste polyester fabric was stripped by DMF stripping system. The effects of feed ratio (mass ratio of deionized water to polyester fabric), reaction temperature and holding time on the degradation rate of PET, whiteness, purity and acidity of the product were discussed. The hydrolysis mechanism of polyethylene terephthalate in subcritical water was explored. The hydrolysis process and reaction mechanism of polyethylene terephthalate under hydrothermal condition were revealed. Finally, the quality indexes of white solid terephthalic acid (TPA) were determined.
(1) The pretreatment of waste polyester fabrics is divided into swelling agent, stripping of disperse dyes and reducing stripping. The swelling agent is DMSO, the stripping agent of disperse dyes is DMF and the reducing agent is thiourea dioxide (TDO). The optimum stripping conditions are determined as follows: The color time is 30min, and the stripping temperature is controlled at 140 C.
(2) The neutral hydrolysis method was used to recover and reuse waste polyester fabrics, and the recycled products were TPA and EG. The feed ratio (mass ratio of deionized water to polyester fabrics), reaction temperature and holding time were the main factors affecting the hydrolysis of polyester fabrics. Under the optimum conditions, the degradation rate of PET was 92.9%, the yield of TPA was 86.4%, the purity of TPA was 98.251%, and the acidity of TPA was 657.14 mg KOH/g.
(3) The hydrolysis mechanism of PET is clarified: water will ionize into H + and OH-, and H + will react with carbonyl group of - COOR to form C+, and water will attack C of - COOR to form tetrahedral intermediate. Then, H in water will leave, electrons on O will transfer, and the acyloxy bond will break, and then it will be degraded into TPA and EG.
(4) The experimental conditions of TPA produced by hydrolysis of PET were defined as follows: reaction temperature (> 250), reaction time (> 8 h), feed ratio (> 10:1), drying temperature (> 100) and drying time (> 8 h).
【學(xué)位授予單位】：太原理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：X791

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