非瀝青粘結(jié)劑煤基活性炭制備及水處理的應(yīng)用研究
發(fā)布時(shí)間：2018-08-19 21:03
【摘要】：煤基活性炭由于其豐富的孔結(jié)構(gòu)及巨大的比表面積，可有效地去除常規(guī)水處理工藝無法解決的溶解性有機(jī)物（DOM）。因此，在微污染水深度處理方面獲得廣泛應(yīng)用，且發(fā)展前景十分廣闊。 目前，煤基活性炭的工業(yè)生產(chǎn)過程中，在添加大量的煤焦油瀝青作為粘結(jié)劑的工藝中，環(huán)境污染嚴(yán)重，而采用新型非瀝青有機(jī)粘結(jié)劑的工藝中，由于高成本使得活性炭生產(chǎn)難度增加。針對(duì)以上問題，本文以廉價(jià)的煤炭為主要原料，采用課題組自主研發(fā)的廉價(jià)高效潔凈非瀝青粘結(jié)劑，通過水蒸汽活化、氧化-催化制備、活性炭處理微污染水以及吸附動(dòng)力學(xué)對(duì)煤基活性炭的性能進(jìn)行了系統(tǒng)的研究，取得的主要研究成果與結(jié)論如下： 1.非瀝青粘結(jié)劑煤基活性炭的優(yōu)化制備操作條件：炭化溫度650℃，炭化時(shí)間45min，活化溫度880℃，活化時(shí)間180min，水蒸汽流量0.04mL·(min·g)-1，在此條作下制得的活性炭碘值853.8mg/g，炭收率44.5%，比表面積684.3m2/g，總孔體積0.3852cm3/g，微孔體積0.2455cm3/g，中孔體積0.1362cm3/g，屬于中微孔發(fā)達(dá)型煤基活性炭。 2.原煤經(jīng)空氣和HNO3氧化后，其內(nèi)部形成碳-氧C（O）微晶耐熱大分子結(jié)構(gòu)化合物，且羰基（C=O）、醚基（C-O-C）和硝基（-NO2）等含氧官能團(tuán)均有明顯的增加。（002）衍射峰強(qiáng)度隨著空氣溫度的升高而逐漸減弱，隨HNO3濃度的增大而呈現(xiàn)先減弱后增強(qiáng)的變化，在空氣溫度240℃和HNO3濃度10%處出現(xiàn)最弱，由于炭化的交聯(lián)與聚合作用，炭化料的石墨化程度大為降低。HNO3氧化后炭化料收率為71.0%，較空氣氧化后的67.5%有所提高。當(dāng)空氣氧化溫度為240℃，碘值出現(xiàn)最大值875.3mg/g，炭收率55.4%，灰分含量41.3%；當(dāng)HNO3氧化濃度為10%時(shí)，碘值出現(xiàn)最大值970.7mg/g，炭收率38.8%，灰分含量24.2%。 3.原煤經(jīng)過氧化后，煤基活性炭表面的C與O的賦存形式發(fā)生明顯變化。其中C主要以石墨碳和烷基碳（C-C）為主，兩者之和占總碳含量的70%以上。經(jīng)空氣氧化后，制得活性炭中石墨碳、酚醚碳和羰基碳含量均有較大的增幅，烷基碳和羧基碳含量均減小，羥醚氧的含量增加21.7%，羧基氧含量減小19.1%；經(jīng)HNO3氧化后，活性炭中烷基碳和羧基碳含量大幅度減小，酚醚碳含量增加，羥醚氧和羧基氧含量分別增加37.0%和40.0%，羰基氧含量減小36.3%。 4.隨著催化劑添加量的增加，煤基活性炭的碘值先增加后減小，灰分含量呈現(xiàn)先減小后增加的趨勢(shì)。添加KNO3制得活性炭的碘值均高于其他兩種硝酸鹽，灰分含量均低于其他兩種硝酸鹽。當(dāng)添加15%的KNO3時(shí)，活性炭碘值出現(xiàn)最大1184mg/g，灰分含量出現(xiàn)最小27.43%。 5.不同硝酸鹽對(duì)制備高性能活性炭的催化活性不同，其順序?yàn)椋篕NO3NaNO3Fe(NO3)3。由于硝酸鹽經(jīng)炭化后部分的晶體產(chǎn)物（K2O、Na2O2和Fe3C等）與氣體產(chǎn)物（O2和NO等）對(duì)煤中分子產(chǎn)生不同程度的破壞，，導(dǎo)致炭化料的石墨化程度下降。其中催化機(jī)理分為兩個(gè)部分，一部分硝酸鹽在炭化過程中釋放出O2和NO，對(duì)煤內(nèi)部支鏈分子進(jìn)行氧化，另一部分由于炭化產(chǎn)生的金屬氧化物在水蒸汽活化反應(yīng)過程中起到催化作用，生成大量的孔隙結(jié)構(gòu)。 6.通過UV-VIS分析，非瀝青粘結(jié)劑煤基活性炭對(duì)微污染水中的烷烴、芳香烴和雜環(huán)等小分子有機(jī)物具有較好的吸附效果，液相吸附等溫線符合非均勻Freundlich吸附模型：q=2.36488·c1.16011，其下限吸附容量較大，吸附容量指數(shù)較小，更適合處理水中濃度較低的有機(jī)物。其處理微污染水的優(yōu)化條件為：吸附時(shí)間150min，投加量2.5g/L，pH值7.80，處理溫度50~60℃，在該條件下對(duì)初始濃度為9.66mg/L的微污染水處理時(shí)，水樣中COD和UV254去除率分別可達(dá)到83.76%和97.78%。 7.活性炭吸附微污染水中小分子有機(jī)物的平衡吸附量均隨吸附時(shí)間和溫度的增加而增大，吸附動(dòng)力學(xué)能夠很好地符合偽二級(jí)動(dòng)力學(xué)方程模型，反應(yīng)速率表達(dá)式：K=499.49·exp(-25310/RT)，其中活化能Ea=25.31kJ/mol，指前因子A=499.49g·(mg·min)-1，且以物理吸附為主。
[Abstract]:Coal-based activated carbon can effectively remove dissolved organic matter (DOM) which can not be solved by conventional water treatment process because of its rich pore structure and huge specific surface area.
At present, in the process of industrial production of coal-based activated carbon, the environmental pollution is serious in the process of adding a large number of coal tar pitch as binder, but in the process of using new non-asphalt organic binder, it is difficult to produce activated carbon because of the high cost. The performance of coal-based activated carbon (CBAC) was systematically studied by steam activation, oxidation-catalysis preparation, activated carbon treatment of slightly polluted water and adsorption kinetics. The main research results and conclusions are as follows:
1. The optimum preparation conditions of coal-based activated carbon without asphalt binder are as follows: carbonization temperature 650 C, carbonization time 45 min, activation temperature 880 C, activation time 180 min, steam flow rate 0.04 mL ((min g) - 1. Under this condition, the iodine value of activated carbon 853.8 mg/g, carbon yield 44.5%, specific surface area 684.3 m2/g, total pore volume 0.3852 cm3/g, micropore volume 0.2 455cm3/g, mesopores volume 0.1362cm3/g, belongs to medium microporous developed coal based activated carbon.
2. The carbon-oxygen C(O) microcrystalline heat-resistant macromolecule structure compound was formed in the raw coal oxidized by air and HNO_3, and the oxygen-containing functional groups such as carbonyl group (C=O), ether group (C-O-C) and nitro group (-NO2) all increased obviously. (002) The diffraction peak intensity decreased gradually with the increase of air temperature, and then increased with the increase of HNO_3 concentration. The graphitization degree of the carbonized material is greatly reduced due to the cross-linking and polymerization of carbonization. The yield of carbonized material is 71.0% after oxidation, which is higher than 67.5% after air oxidation. When the air oxidation temperature is 240 C, the maximum iodine value is 875.3 mg/g, the carbon yield is 55.4%, and the ash content is increased. 41.3%. When the HNO_3 oxidation concentration was 10%, the iodine value reached a maximum of 970.7 mg/g, the carbon yield was 38.8%, and the ash content was 24.2%.
3. The occurrence of C and O on the surface of coal-based activated carbon changed obviously after the oxidation of raw coal. C was mainly composed of graphite carbon and alkyl carbon (C-C), which accounted for more than 70% of the total carbon. After air oxidation, graphite carbon, phenol ether carbon and carbonyl carbon content in activated carbon increased greatly, alkyl carbon and carboxyl carbon content increased. The content of hydroxyether oxygen increased by 21.7% and the content of carboxyl oxygen decreased by 19.1%. After HNO3 oxidation, the content of alkyl carbon and carboxyl carbon in activated carbon decreased greatly, the content of phenol ether carbon increased, the content of hydroxyether oxygen and carboxyl oxygen increased by 37.0% and 40.0% respectively, and the content of carbonyl oxygen decreased by 36.3%.
4. With the increase of catalyst dosage, the iodine value of coal-based activated carbon increases first and then decreases, while the ash content decreases first and then increases. The iodine value of activated carbon prepared by adding KNO3 is higher than that of the other two nitrates, and the ash content is lower than that of the other two nitrates. The content was minimum 27.43%.
5. Different nitrates have different catalytic activities for the preparation of high performance activated carbon. The sequence is: KNO3NaNO3Fe (NO3) 3. The graphitization degree of carbonized materials is decreased because the crystalline products (K2O, Na2O2, Fe3C, etc.) of nitrates and gaseous products (O2, NO, etc.) destroy the molecule in coal in varying degrees. There are two parts: one part of nitrate releases O2 and NO during carbonization, oxidizing branched chain molecules in coal, and the other part of metal oxides produced by carbonization play a catalytic role in steam activation reaction, resulting in a large number of pore structures.
6. Through UV-VIS analysis, the coal-based activated carbon with non-asphalt binder has better adsorption effect on small molecular organic compounds such as alkanes, aromatic hydrocarbons and heterocycles in slightly polluted water. The adsorption isotherm of liquid phase conforms to the non-uniform Freundlich adsorption model: q=2.36488.c1.16011, which has larger lower adsorption capacity and smaller adsorption capacity index, so it is more suitable for treatment. The optimum conditions for the treatment of micro-polluted water are as follows: adsorption time 150 min, dosage 2.5 g/L, pH 7.80, treatment temperature 50-60 C. Under these conditions, the removal rates of COD and UV254 in the water sample can reach 83.76% and 97.78% respectively when the initial concentration of 9.66 mg/L is treated.
7. Equilibrium adsorption capacity of activated carbon for small molecule organic compounds in slightly polluted water increases with the increase of adsorption time and temperature. Adsorption kinetics is in good agreement with pseudo-second-order kinetic equation model. The reaction rate expression is K=499.49.exp(-25310/RT), in which activation energy Ea=25.31kJ/mol, pre-exponential factor A=499.49g ((mg min))-1 and the activation energy Ea=25.31kJ/mol. Physical adsorption is the main method.
【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)】：X703;TQ424.11
本文編號(hào)：2192825
[Abstract]:Coal-based activated carbon can effectively remove dissolved organic matter (DOM) which can not be solved by conventional water treatment process because of its rich pore structure and huge specific surface area.
At present, in the process of industrial production of coal-based activated carbon, the environmental pollution is serious in the process of adding a large number of coal tar pitch as binder, but in the process of using new non-asphalt organic binder, it is difficult to produce activated carbon because of the high cost. The performance of coal-based activated carbon (CBAC) was systematically studied by steam activation, oxidation-catalysis preparation, activated carbon treatment of slightly polluted water and adsorption kinetics. The main research results and conclusions are as follows:
1. The optimum preparation conditions of coal-based activated carbon without asphalt binder are as follows: carbonization temperature 650 C, carbonization time 45 min, activation temperature 880 C, activation time 180 min, steam flow rate 0.04 mL ((min g) - 1. Under this condition, the iodine value of activated carbon 853.8 mg/g, carbon yield 44.5%, specific surface area 684.3 m2/g, total pore volume 0.3852 cm3/g, micropore volume 0.2 455cm3/g, mesopores volume 0.1362cm3/g, belongs to medium microporous developed coal based activated carbon.
2. The carbon-oxygen C(O) microcrystalline heat-resistant macromolecule structure compound was formed in the raw coal oxidized by air and HNO_3, and the oxygen-containing functional groups such as carbonyl group (C=O), ether group (C-O-C) and nitro group (-NO2) all increased obviously. (002) The diffraction peak intensity decreased gradually with the increase of air temperature, and then increased with the increase of HNO_3 concentration. The graphitization degree of the carbonized material is greatly reduced due to the cross-linking and polymerization of carbonization. The yield of carbonized material is 71.0% after oxidation, which is higher than 67.5% after air oxidation. When the air oxidation temperature is 240 C, the maximum iodine value is 875.3 mg/g, the carbon yield is 55.4%, and the ash content is increased. 41.3%. When the HNO_3 oxidation concentration was 10%, the iodine value reached a maximum of 970.7 mg/g, the carbon yield was 38.8%, and the ash content was 24.2%.
3. The occurrence of C and O on the surface of coal-based activated carbon changed obviously after the oxidation of raw coal. C was mainly composed of graphite carbon and alkyl carbon (C-C), which accounted for more than 70% of the total carbon. After air oxidation, graphite carbon, phenol ether carbon and carbonyl carbon content in activated carbon increased greatly, alkyl carbon and carboxyl carbon content increased. The content of hydroxyether oxygen increased by 21.7% and the content of carboxyl oxygen decreased by 19.1%. After HNO3 oxidation, the content of alkyl carbon and carboxyl carbon in activated carbon decreased greatly, the content of phenol ether carbon increased, the content of hydroxyether oxygen and carboxyl oxygen increased by 37.0% and 40.0% respectively, and the content of carbonyl oxygen decreased by 36.3%.
4. With the increase of catalyst dosage, the iodine value of coal-based activated carbon increases first and then decreases, while the ash content decreases first and then increases. The iodine value of activated carbon prepared by adding KNO3 is higher than that of the other two nitrates, and the ash content is lower than that of the other two nitrates. The content was minimum 27.43%.
5. Different nitrates have different catalytic activities for the preparation of high performance activated carbon. The sequence is: KNO3NaNO3Fe (NO3) 3. The graphitization degree of carbonized materials is decreased because the crystalline products (K2O, Na2O2, Fe3C, etc.) of nitrates and gaseous products (O2, NO, etc.) destroy the molecule in coal in varying degrees. There are two parts: one part of nitrate releases O2 and NO during carbonization, oxidizing branched chain molecules in coal, and the other part of metal oxides produced by carbonization play a catalytic role in steam activation reaction, resulting in a large number of pore structures.
6. Through UV-VIS analysis, the coal-based activated carbon with non-asphalt binder has better adsorption effect on small molecular organic compounds such as alkanes, aromatic hydrocarbons and heterocycles in slightly polluted water. The adsorption isotherm of liquid phase conforms to the non-uniform Freundlich adsorption model: q=2.36488.c1.16011, which has larger lower adsorption capacity and smaller adsorption capacity index, so it is more suitable for treatment. The optimum conditions for the treatment of micro-polluted water are as follows: adsorption time 150 min, dosage 2.5 g/L, pH 7.80, treatment temperature 50-60 C. Under these conditions, the removal rates of COD and UV254 in the water sample can reach 83.76% and 97.78% respectively when the initial concentration of 9.66 mg/L is treated.
7. Equilibrium adsorption capacity of activated carbon for small molecule organic compounds in slightly polluted water increases with the increase of adsorption time and temperature. Adsorption kinetics is in good agreement with pseudo-second-order kinetic equation model. The reaction rate expression is K=499.49.exp(-25310/RT), in which activation energy Ea=25.31kJ/mol, pre-exponential factor A=499.49g ((mg min))-1 and the activation energy Ea=25.31kJ/mol. Physical adsorption is the main method.
【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)】：X703;TQ424.11
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