改性生物炭的制备及其对水中镉离子的吸附试验
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摘要
以稻壳为原料,采用预浸渍-热解法制备原始稻壳生物炭(C)、CaCl_2改性的稻壳生物炭(Ca-C)、CaCl_2与H_2O_2混合改性的稻壳生物炭(Ca H-C),探讨改性生物炭对水中Cd~(2+)的去除能力。结果表明:改性生物炭具有较大的比表面结和总孔容积。CaCl_2改性和CaCl_2与H_2O_2混合改性可显著提高生物炭对Cd~(2+)的吸附能力,其中CaCl_2与H_2O_2混合改性效果要优于CaCl_2改性。Ca-C和CaH-C对Cd~(2+)吸附符合Langmuir吸附等温模型,饱和吸附量可分别达到19. 53,37. 45 mg/g。改性生物炭主要以离子交换的方式对水中Cd~(2+)进行去除,少量Cd~(2+)在生物炭或生成的CaCO_3表面进行物理吸附。
Original rice husk biochar( C),CaCl_2 modified biochars( Ca-C) and CaCl_2 and H_2O_2 mixed modified rice husk biochar( Ca H-C) were prepared by preimpregnation-thermal decomposition method,with rice husks as the raw materials. The ability of modified biochars to remove Cd~(2+)from water was discussed. The results showed that the modified biochar had a larger specific surface area and total pore volume. The modification of CaCl_2 and the mixed modification of CaCl_2 and H_2O_2 can significantly improve the adsorption capacity of biochar for Cd~(2+). The effect of biochar under CaCl_2 and H_2O_2 mixed modification was better than that of CaCl_2 modification. The adsorption isotherm of Ca-C and CaH-C for Cd~(2+)could be described by Langmuir model,and the saturated adsorption quantities of Ca-C and CaH-C for Cd~(2+)can respectively reach19. 53 and 37. 45 mg/g. The modified biochars mainly removed Cd~(2+)from water by ion exchange,and a small amount of Cd~(2+)was physically adsorbed on the surface of biochars or CaCO_3 generated.
Original rice husk biochar( C),CaCl_2 modified biochars( Ca-C) and CaCl_2 and H_2O_2 mixed modified rice husk biochar( Ca H-C) were prepared by preimpregnation-thermal decomposition method,with rice husks as the raw materials. The ability of modified biochars to remove Cd~(2+)from water was discussed. The results showed that the modified biochar had a larger specific surface area and total pore volume. The modification of CaCl_2 and the mixed modification of CaCl_2 and H_2O_2 can significantly improve the adsorption capacity of biochar for Cd~(2+). The effect of biochar under CaCl_2 and H_2O_2 mixed modification was better than that of CaCl_2 modification. The adsorption isotherm of Ca-C and CaH-C for Cd~(2+)could be described by Langmuir model,and the saturated adsorption quantities of Ca-C and CaH-C for Cd~(2+)can respectively reach19. 53 and 37. 45 mg/g. The modified biochars mainly removed Cd~(2+)from water by ion exchange,and a small amount of Cd~(2+)was physically adsorbed on the surface of biochars or CaCO_3 generated.
引文
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[2] Dong X L,Ma L Q,Li Y C. Characteristics and mechanisms of hexavalent chromium removal by biochar from sugar beet tailing[J]. Journal of Hazardous Materials,2011,190(1/2/3):909-915.
[3] Dong X L,Ma L Q,Zhu Y J,et al. Mechanistic investigation of mercury sorption by brazilian pepper biochars of different pyrolytic temperatures based on X-ray photoelectron spectroscopy and flow calorimetry[J]. Environmental Science&Technology,2013,47(21):12156-12164.
[4]于志红.锰氧化物-生物炭复合材料对砷的生物有效性的影响[D].北京:中国农业科学院,2015.
[5]张越,林珈羽,刘沅,等.改性生物炭对镉离子吸附性能研究[J].武汉科技大学学报,2016,39(1):48-52.
[6] Hadjittofi L,Prodromou M,Pashalidis I. Activated biochar derived from cactus fibres-Preparation,characterization and application on Cu(Ⅱ)removal from aqueous solutions[J]. Bioresource Technology,2014,159(5):460-464.
[7] Regmi P,Garcia J M,Kumar S,et al. Removal of copper and cadmium from aqueous solution using switchgrass biochar produced via hydrothermal carbonization process[J]. Journal of Environmental Management,2012,109(17):61-69.
[8] Peng H,Gao P,Chu G,et al. Enhanced adsorption of Cu(Ⅱ)and Cd(Ⅱ)by phosphoric acid-modified biochars[J].Environmental Pollution,2017,229(2):846-853.
[9] Xue Y W,Gao B,Yao Y,et al. Hydrogen peroxide modification enhances the ability of biochar(hydrochar)produced from hydrothermal carbonization of peanut hull to remove aqueous heavy metals:batch and column tests[J]. Chemical Engineering Journal,2012,200/202(34):673-680.
[10] Wang S S, Gao B. Removal of arsenic by magnetic biochar prepared from pinewood and natural hematite[J]. Bioresource Technology,2015,175:391-395.
[11] Zhang M,Gao B,Varnoosfaderani S,et al. Preparation and characterization of a novel magnetic biochar for arsenic removal[J].Bioresource Technology,2013,130(1):457-462.
[12] Zhang M,Gao B. Removal of arsenic,methylene blue, and phosphate by biochar/Al OOH nanocomposite[J]. Chemical Engineering Journal,2013,226(24):286-292.
[13] Han Y T,Xi C,Xin O Y,et al. Adsorption kinetics of magnetic biochar derived from peanut hull on removal of Cr(Ⅵ)from aqueous solution:effects of production conditions and particle size[J]. Chemosphere,2016,145(9):336-341.
[14]吴光前,孙新元,张齐生.活性炭表面氧化改性技术及其对吸附性能的影响[J].浙江农林大学学报,2011,28(6):955-961.
[15]韩鹏,任爱玲,郭斌,等.过氧化氢改性活性炭对三甲胺废气的吸附[J].河北科技大学学报,2013,34(2):159-165.
[16] Fang C,Zhang T,Li P,et al. Phosphorus recovery from biogas fermentation liquid by Ca-Mg loaded biochar[J]. Journal of Environmental Sciences,2015,29(3):106-114.
[17]赵明静,杜霞,郭萌,等. CaCl2改性生物炭的制备及其对Pb2+的吸附作用[J].环境污染与防治,2016,38(10):84-88,93.
[18]吴绍吟,练恩生.纳米碳酸钙的特点与应用[J].橡胶工业,1999(3):18-23.
[19]汪洪,周卫,林葆.碳酸钙对土壤镉吸附及解吸的影响[J].生态学报,2001,21(6):932-937.