水中痕量全氟化合物的分析檢測及納濾膜去除特性研究
發(fā)布時間：2018-11-15 21:59
【摘要】：全氟化合物(PFCs)在土壤、水體及生物體內(nèi)廣泛存在,具有持久性、污染性、生物積累性和難降解性等特點,其中全氟辛基磺酸及其鹽已經(jīng)引起了國內(nèi)外學(xué)者的廣泛重視,并且被列為持久性有機(jī)污染物(POPs)。本文將四種全氟化合物作為研究目標(biāo),建立了四種全氟化合物的環(huán)境樣品前處理及儀器分析方法,并通過小型錯流納濾膜過濾裝置研究了無機(jī)鹽、有機(jī)物存在條件下,納濾膜對不同分子量全氟化合物的去除效果。通過試驗研究,得出以下結(jié)果:(1)樣品前處理的最優(yōu)化固相萃取條件為:活化溶液為氨水甲醇和去離子水,滴速為2滴/s,水樣滴速為2滴/s;淋洗液為40%甲醇水(pH=5),滴速為2滴/s;洗脫液為0.1%氨水甲醇溶液,滴速為1滴/s,以上步驟溶劑體積均為4m L。采用超高效液相色譜-質(zhì)譜聯(lián)用(UPLC-MS/MS)對水中痕量PFCs進(jìn)行了測定,方法檢出限為0.06ng/L-0.22ng/L,加標(biāo)回收率為73.1%-91.3%,相對標(biāo)準(zhǔn)偏差為7.4%-14.3%。測定結(jié)果顯示,該方法線性好,準(zhǔn)確度高,能滿足環(huán)境水樣中痕量PFCs的測定要求。(2)分別采用純水、添加無機(jī)鹽(氯化鈉,氯化鈣)、添加有機(jī)物(海藻酸鈉SA、牛血清白蛋白BSA、腐殖酸HA)以及同時添加無機(jī)鹽與有機(jī)物的溶液與PFCs標(biāo)準(zhǔn)物質(zhì)配成一定濃度的PFCs原水,研究納濾在這幾種水質(zhì)條件下對PFCs的去除特性。研究發(fā)現(xiàn)下列因素影響納濾膜對PFCs的去除效果:(1)純水條件下,由于較高的相對分子量,納濾膜對全氟辛基磺酸(PFOS)的篩分作用強(qiáng)于全氟丁基磺酸(PFBS)。(2)添加無機(jī)鹽條件下,膜面雙電層被壓縮,靜電斥力的減小導(dǎo)致截留率下降,膜孔收縮導(dǎo)致截留率上升,鈣離子會在PFCs之間,PFCs與膜面之間產(chǎn)生架橋作用,污染物體積增大,提高截留率,綜合作用下,納濾膜對PFOS的截留率較純水時增大,對PFBS的截留率較純水時下降。(3)有機(jī)物存在時,SA與HA提高膜面電位,則靜電斥力增大,使得PFCs的截留率提高;BSA主要通過其復(fù)雜的空間結(jié)構(gòu)及較大的分子量使PFCs吸附于其表面,來提高膜對于PFCs的截留率,最終膜對于PFOS的截留率較純水時有所提高,PFBS的截留率較純水時基本相同。(4)無機(jī)鹽與有機(jī)物共存時,膜電位的變化引起的靜電斥力的變化是影響膜對PFOS以及PFBS的主要作用,同樣膜孔收縮增強(qiáng)的篩分作用也有一定的影響。同時相比于(2),由于SA中含一定量的羧基和羥基,HA含有一定量的羧基及少量羧基,BSA中含少量的羧基和氨基,鈣離子還會使有機(jī)物分子發(fā)生絡(luò)合作用,以上綜合作用,使膜對于PFOS的截留率較純水時增大,而膜對于PFBS的截留率較純水時基本相同。
[Abstract]:Perfluorooctane sulfonic acid (PFOS) and its salts are widely used in soils, water bodies and organisms, and have the characteristics of persistence, pollution, bioaccumulation and non-biodegradability, among which perfluorooctane sulfonic acid and its salts have attracted extensive attention of scholars at home and abroad. And listed as persistent organic pollutant (POPs). In this paper, four kinds of perfluorinated compounds were taken as the research object, the methods of environmental sample pretreatment and instrumental analysis of four perfluorocarbons were established, and the inorganic salts and organic compounds were studied by means of a small cross-flow nanofiltration membrane filtration device. Removal of perfluorocarbons with different molecular weight by nanofiltration membrane. The results are as follows: (1) the optimal solid-phase extraction conditions for sample pretreatment are as follows: the activated solution is ammonia water methanol and deionized water, the droplet rate is 2 drops / s, and the water sample droplet velocity is 2 drops / s; The eluent was 40% methanol-water (pH=5) at a drop rate of 2 drops / s, and the elution solution was 0.1% ammonia water methanol solution with a drop rate of 1 drop / s, and the volume of the above steps was 4 mL. UPLC-MS/MS was used to determine trace PFCs in water. The detection limit was 0.06 ng / L -0.22 ng / L, and the recovery rate was 73.1% -91.3%. The relative standard deviation was 7.4- 14.3cm. The results show that the method has good linearity and high accuracy, and can meet the determination requirements of trace PFCs in environmental water samples. (2) Inorganic salts (sodium chloride, calcium chloride) and organic compounds (sodium alginate, SA,) are added respectively in pure water, inorganic salts (sodium chloride, calcium chloride) and organic compounds (sodium alginate). Bovine serum albumin (BSA) BSA, humic acid (HA), the solution of inorganic salt and organic matter and PFCs standard material were used to prepare PFCs raw water of a certain concentration. The removal characteristics of PFCs by nanofiltration under these water conditions were studied. It is found that the following factors affect the removal efficiency of PFCs by nanofiltration membrane: (1) under pure water conditions, due to higher relative molecular weight, The screening effect of nanofiltration membrane on perfluorooctane sulfonic acid (PFOS) was stronger than that on perfluorooctane sulfonic acid (PFBS). (_ 2). When the inorganic salt was added, the double electric layer on the membrane surface was compressed, and the reduction of electrostatic repulsion resulted in the decrease of the rejection rate. The shrinkage of membrane pore led to the increase of rejection rate, and calcium ion would bridge between PFCs, PFCs and membrane surface. The volume of pollutants increased, and the rejection rate of PFOS increased. The rejection rate of nanofiltration membrane was higher than that of pure water. The rejection rate of PFBS was lower than that of pure water. (3) in the presence of organic matter, SA and HA increased the potential of membrane surface, the electrostatic repulsion increased, and the rejection rate of PFCs increased. The adsorption of PFCs on the surface of BSA is mainly due to its complex spatial structure and large molecular weight, which can improve the retention rate of PFCs on the membrane. Finally, the rejection rate of the membrane to PFOS is higher than that of pure water. The rejection rate of PFBS is almost the same as that of pure water. (4) the change of electrostatic repulsion induced by the change of membrane potential is the main effect of membrane on PFOS and PFBS when inorganic salt and organic matter coexist. At the same time, the screening effect of membrane pore shrinkage enhancement also has certain effect. At the same time, compared with (2), because SA contains a certain amount of carboxyl group and hydroxyl group, HA contains a certain amount of carboxyl group and a small amount of carboxyl group, BSA contains a small amount of carboxyl group and amino group, and calcium ion also makes organic molecule complex. The rejection rate of membrane to PFOS was higher than that of pure water, but the rejection rate of membrane to PFBS was almost the same as that of pure water.
【學(xué)位授予單位】：西安建筑科技大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：X832
[Abstract]:Perfluorooctane sulfonic acid (PFOS) and its salts are widely used in soils, water bodies and organisms, and have the characteristics of persistence, pollution, bioaccumulation and non-biodegradability, among which perfluorooctane sulfonic acid and its salts have attracted extensive attention of scholars at home and abroad. And listed as persistent organic pollutant (POPs). In this paper, four kinds of perfluorinated compounds were taken as the research object, the methods of environmental sample pretreatment and instrumental analysis of four perfluorocarbons were established, and the inorganic salts and organic compounds were studied by means of a small cross-flow nanofiltration membrane filtration device. Removal of perfluorocarbons with different molecular weight by nanofiltration membrane. The results are as follows: (1) the optimal solid-phase extraction conditions for sample pretreatment are as follows: the activated solution is ammonia water methanol and deionized water, the droplet rate is 2 drops / s, and the water sample droplet velocity is 2 drops / s; The eluent was 40% methanol-water (pH=5) at a drop rate of 2 drops / s, and the elution solution was 0.1% ammonia water methanol solution with a drop rate of 1 drop / s, and the volume of the above steps was 4 mL. UPLC-MS/MS was used to determine trace PFCs in water. The detection limit was 0.06 ng / L -0.22 ng / L, and the recovery rate was 73.1% -91.3%. The relative standard deviation was 7.4- 14.3cm. The results show that the method has good linearity and high accuracy, and can meet the determination requirements of trace PFCs in environmental water samples. (2) Inorganic salts (sodium chloride, calcium chloride) and organic compounds (sodium alginate, SA,) are added respectively in pure water, inorganic salts (sodium chloride, calcium chloride) and organic compounds (sodium alginate). Bovine serum albumin (BSA) BSA, humic acid (HA), the solution of inorganic salt and organic matter and PFCs standard material were used to prepare PFCs raw water of a certain concentration. The removal characteristics of PFCs by nanofiltration under these water conditions were studied. It is found that the following factors affect the removal efficiency of PFCs by nanofiltration membrane: (1) under pure water conditions, due to higher relative molecular weight, The screening effect of nanofiltration membrane on perfluorooctane sulfonic acid (PFOS) was stronger than that on perfluorooctane sulfonic acid (PFBS). (_ 2). When the inorganic salt was added, the double electric layer on the membrane surface was compressed, and the reduction of electrostatic repulsion resulted in the decrease of the rejection rate. The shrinkage of membrane pore led to the increase of rejection rate, and calcium ion would bridge between PFCs, PFCs and membrane surface. The volume of pollutants increased, and the rejection rate of PFOS increased. The rejection rate of nanofiltration membrane was higher than that of pure water. The rejection rate of PFBS was lower than that of pure water. (3) in the presence of organic matter, SA and HA increased the potential of membrane surface, the electrostatic repulsion increased, and the rejection rate of PFCs increased. The adsorption of PFCs on the surface of BSA is mainly due to its complex spatial structure and large molecular weight, which can improve the retention rate of PFCs on the membrane. Finally, the rejection rate of the membrane to PFOS is higher than that of pure water. The rejection rate of PFBS is almost the same as that of pure water. (4) the change of electrostatic repulsion induced by the change of membrane potential is the main effect of membrane on PFOS and PFBS when inorganic salt and organic matter coexist. At the same time, the screening effect of membrane pore shrinkage enhancement also has certain effect. At the same time, compared with (2), because SA contains a certain amount of carboxyl group and hydroxyl group, HA contains a certain amount of carboxyl group and a small amount of carboxyl group, BSA contains a small amount of carboxyl group and amino group, and calcium ion also makes organic molecule complex. The rejection rate of membrane to PFOS was higher than that of pure water, but the rejection rate of membrane to PFBS was almost the same as that of pure water.
【學(xué)位授予單位】：西安建筑科技大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：X832
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