【摘要】：可吸附有機(jī)鹵化物(AOX)主要來源于制漿造紙漂白階段,以二氧化氯為主的無元素氯(ECF)漂白技術(shù)雖然可以大幅度降低廢水中AOX的含量,但是由于制漿造紙廢水排放量大,AOX排放到自然環(huán)境中的總量在不斷增加。AOX屬于持久性有機(jī)污染物(POPs),具有長(zhǎng)期殘留性、生物蓄積性、高毒性和長(zhǎng)距離遷移性,經(jīng)自然降解后,含量減少甚微,對(duì)環(huán)境的危害越來越大。果殼類活性炭是一種孔隙發(fā)達(dá)、比表面積大、吸附能力強(qiáng)的功能型碳材料,被廣泛應(yīng)用于環(huán)保領(lǐng)域。本論文詳細(xì)探究了無元素氯漂白廢水中AOX的自然降解規(guī)律,以果殼類活性炭吸附漂白廢水中的AOX,并對(duì)吸附條件進(jìn)行工藝優(yōu)化,建立活性炭吸附2,4,6-三氯苯酚(TCP)和1,2,4-三氯苯(TCB)的動(dòng)力學(xué)模型,為監(jiān)測(cè)實(shí)際環(huán)境中AOX污染物的分布提供理論依據(jù)。1.漂白廢水經(jīng)過45天自然降解后,AOX含量由25.98 mg.L~-1降低到21.97 mg.L~-1 通過氣質(zhì)聯(lián)用(GC-MS)分析發(fā)現(xiàn)漂白廢水自然降解后氯乙酸、氯丙酮等小分子物質(zhì)含量有所降低,氯苯、氯苯酚等大分子有機(jī)氯化物含量變化不明顯。2.利用XRD分析發(fā)現(xiàn)活性炭以非晶型結(jié)構(gòu)為主,SEM觀察發(fā)現(xiàn)其表面有豐富的孔隙結(jié)構(gòu)。通過多站比表面積測(cè)試儀(BET)測(cè)得:活性炭比表面積為1241m2.g 1、平均孔徑為2.21 nm,利用測(cè)試數(shù)據(jù)分析發(fā)現(xiàn)活性炭孔徑主要集中在1-4nm,而且具有大量的微孔和中孔,屬于Ⅳ型吸附等溫線。3.通過單因素實(shí)驗(yàn)和響應(yīng)面分析技術(shù)對(duì)AOX的吸附條件進(jìn)行優(yōu)化:活性炭的粒徑為75 um,吸附時(shí)間為100 min,吸附溫度50℃,活性炭的投加量為1.50 g.L~-1,廢水pH值為2.47時(shí),能達(dá)到的最大吸附量為4.385 mg.g~-1。利用GC-MS分析活性炭處理前后的漂白廢水結(jié)果顯示:經(jīng)活性炭吸附后的漂白廢水中,氯丙酮、2-氯-對(duì)苯二酚、二氯苯基酯、三氯苯、三氯苯酚均被大量去除。EDAX能譜顯示:在吸附AOX后的活性炭上,氯元素由0.01%增加到2.32%。4.以2,4,6-TCP和1,2,4-TCB為AOX模擬物,利用吸附動(dòng)力學(xué)模型和吸附等溫模型對(duì)吸附實(shí)驗(yàn)數(shù)據(jù)進(jìn)行擬合。其中,活性炭對(duì)2,4,6-TCP的吸附過程符合二級(jí)動(dòng)力學(xué)模型和Freundlich等溫模型,二級(jí)動(dòng)力學(xué)模型和Langmuir等溫吸附模型能夠很好地描述活性炭對(duì)1,2,4-TCB的吸附過程。通過Dumwald-Wagner公式對(duì)吸附機(jī)理進(jìn)探討發(fā)現(xiàn),吸附過程除了顆粒內(nèi)擴(kuò)散外還有其他控制步驟。吸附熱力學(xué)實(shí)驗(yàn)結(jié)果證明兩者的吸附過程均屬于放熱反應(yīng)。
[Abstract]:Adsorbable organic halide (AOX) mainly comes from pulping and papermaking bleaching stage. Although chlorine dioxide based non-elemental chlorine (ECF) bleaching technology can greatly reduce the content of AOX in wastewater, the discharge of pulp and papermaking wastewater is large. The total amount of AOX released into the natural environment is increasing. AOX is a persistent organic pollutant, (POPs), has long-term residual, bioaccumulation, high toxicity and long distance migration. After natural degradation, the content of AOX decreases very little. The damage to the environment is getting bigger and bigger. Shell activated carbon is a kind of functional carbon material with developed pores, large specific surface area and strong adsorption ability, which is widely used in environmental protection field. In this paper, the natural degradation law of AOX in elemental chlorine bleaching wastewater was studied in detail. The adsorption conditions of AOX, in bleaching wastewater were optimized with shell activated carbon, and the adsorption conditions were optimized to establish the adsorption of 2N 4N 6 trichlorophenol (TCP) and 1 trichlorophenol by activated carbon. The kinetic model of 4-trichlorobenzene (TCB) provides a theoretical basis for monitoring the distribution of AOX pollutants in real environment. 1. After 45 days of natural degradation of bleaching wastewater, the content of AOX was reduced from 25.98 mg.L~-1 to 21.97 mg.L~-1. The results of GC-MS analysis showed that chloroacetic acid was degraded naturally from bleaching wastewater. The content of small molecular substances such as chloroacetone decreased, while the content of macromolecular organic chlorides such as chlorophenol did not change obviously. 2. The amorphous structure of activated carbon was found by XRD analysis, and the pore structure on the surface of activated carbon was found by SEM. The specific surface area of activated carbon is 1241m2.g 1, and the average pore size is 2.21 nm,. By analyzing the measured data, it is found that the pore size of activated carbon is mainly concentrated in 1-4 nm, and has a large number of micropores and mesoporous pores. It belongs to type 鈪，

本文編號(hào)：2386741