【摘要】：纖維素是世界上最豐富的天然有機(jī)物,具有很多優(yōu)良特性,如生物可降解性、高親水性、熱化穩(wěn)定性,由纖維素所制備的再生纖維素膜完全保留了其優(yōu)良特性。生物可降解性對環(huán)境友好,符合可持續(xù)發(fā)展戰(zhàn)略;高親水性可大大降低膜的污染;熱化穩(wěn)定性可用于條件更為苛刻的環(huán)境,如酸堿體系、有機(jī)溶劑體系。本論文以棉槳為原料,低溫下溶解在9.5wt%NaOH/4.5wt%硫脲水溶液中,通過改變制膜條件來調(diào)控再生纖維素(RC)膜的結(jié)構(gòu)和性能,并探討了干燥方式對膜結(jié)構(gòu)與性能的影響,最后對RC膜進(jìn)行了耐酸堿性和油水分離應(yīng)用作了初步研究。首先,通過在鑄膜液中加入添加劑、不同凝固浴及溶劑配比條件探究制膜條件對RC膜結(jié)構(gòu)與性能的影響。結(jié)果表明,隨LiCl含量的增加,RC膜水通量、孔徑和結(jié)晶度均增加,而對牛血清白蛋白(BSA)截留率減小,LiCl促進(jìn)孔生成,起致孔作用。RC膜水通量、孔徑和結(jié)晶度隨ZnCl2含量的增加先減小后增加,而BSA截留率一直減小,ZnCl2先抑制后促進(jìn)孔的形成。以DMAc作凝固浴制備的RC膜,孔徑最大,通量最高,NMP凝固浴制備的RC膜,孔徑最小,通量最低,但結(jié)晶度最高。DMAc水溶液作凝固浴時,隨著DMAc含量的增加,水通量增加,BSA截留率降低。不同混合溶劑實驗中,得到RC-LU膜的孔徑、通量、結(jié)晶度和拉伸強(qiáng)度均最小,RC-LTU膜的孔徑和通量最大,RC-NU膜結(jié)晶度和拉伸強(qiáng)度最大。其次,比較了不同干燥方式對RC膜結(jié)構(gòu)的影響。冷凍干燥方式較好地保留了RC膜的多孔結(jié)構(gòu),逐級脫水僅保留了少部分孔結(jié)構(gòu),自然干燥和加熱干燥不能保留RC膜的多孔結(jié)構(gòu)。RC膜在干燥過程中結(jié)晶度會進(jìn)行增長,四種干燥方式下的RC膜結(jié)晶度大小為:冷凍干燥自然干燥逐級脫水干燥加熱干燥。最后,對RC膜進(jìn)行耐酸堿性測定,其在pH1-14的水溶液中浸泡一周后,水通量、面積變化率和重量變化率僅有微小變化。在對不同pH的含油乳液處理過程中,溶液通量與水通量相比,僅有少量降低,對油的截留率都在98%以上,展現(xiàn)了較高的截留性能。經(jīng)過水沖洗10min,水通量恢復(fù)率在90%左右,說明RC膜具有優(yōu)良的抗油污染性。
[Abstract]:Cellulose is one of the most abundant natural organic compounds in the world. It has many excellent properties, such as biodegradability, high hydrophilicity and thermal stability. The regenerated cellulose membrane prepared from cellulose completely retains its excellent properties. Biodegradability is environmentally friendly and consistent with sustainable development strategy; high hydrophilicity can greatly reduce membrane fouling; thermal stability can be used in more demanding environments such as acid-base system and organic solvent system. In this paper, cotton oars were used as raw materials and dissolved in aqueous solution of NaOH / 4.5 wt% thiourea at low temperature. The structure and properties of regenerated cellulose (RC) membranes were regulated by changing the conditions of membrane preparation. The effects of drying methods on the structure and properties of the membrane were discussed. Finally, the acid and alkaline resistance of RC membrane and the application of oil and water separation were studied preliminarily. Firstly, the effects of different coagulation bath and solvent ratio on the structure and properties of RC membrane were investigated by adding additives into the casting solution. The results showed that with the increase of LiCl content, the water flux, pore size and crystallinity of RC membrane increased, while the (BSA) rejection of bovine serum albumin (BSA) decreased, and LiCl promoted pore formation, which resulted in pore formation. The water flux of RC membrane increased. The pore size and crystallinity decreased firstly and then increased with the increase of ZnCl2 content, while the rejection rate of BSA decreased. ZnCl2 inhibited the pore formation first and then promoted the formation of pore. RC membrane prepared by DMAc as coagulation bath has the largest pore size and highest flux. The RC membrane prepared by NMP coagulation bath has the smallest pore size and the lowest flux, but its crystallinity is the highest. With the increase of DMAc content, the water flux increases with the increase of DMAc content. The rejection rate of BSA decreased. The pore size, flux, crystallinity and tensile strength of RC-LU membrane were the smallest, the pore size and flux of RC-LTU membrane were the largest, and the crystallinity and tensile strength of RC-NU membrane were the largest. Secondly, the effects of different drying methods on the structure of RC membrane were compared. The porous structure of RC membrane was well preserved by freeze-drying method, and only a few pore structures were retained by step dehydration. The porous structure of RC film could not be preserved by natural drying and heating drying. The crystallinity of RC film would increase during drying. The crystallinity of RC film under four drying methods is as follows: freeze-drying, natural drying, step by step dehydration, drying, heating and drying. Finally, the acid and alkali resistance of RC membrane was determined. After immersion in pH1-14 aqueous solution for one week, the water flux, area change rate and weight change rate were only slightly changed. In the treatment of different pH emulsion containing oil, the flux of solution is only a little lower than that of water flux, and the rejection rate of oil is above 98%, which shows high retention performance. After water washing for 10 min, the recovery rate of water flux is about 90%, which indicates that RC membrane has excellent resistance to oil pollution.
【學(xué)位授予單位】：浙江工業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TQ051.893

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本文編號：2298142