1. Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming 650500, China; 2. Yunnan Institute of Environmental Science, Kunming 650034, China
Abstract：Biochar is a solid product produced by pyrolysis of waste biomass under anaerobic oxygen conditions. Because of its porosity, large specific surface area, rich oxygen-containing functional groups, rich minerals and strong stability, biochar has been widely used in the remediation of heavy metal contaminated soils. The passivation effect of biochar on heavy metals is affected by not only the properties of heavy metals and biochar, but also organic acids secreted from plant rhizosphere in soil. However, the effects of organic acids on biochar-heavy metal interactions have not been studied limitedly. Therefore, in this paper, oxalic acid and citric acid were chosen as organic acids to explore the mechanisim on the adsorption behavior change of Pb(Ⅱ) on biochars (different pyrolysis temperatures at 200, 300, 400and 500℃). Comparing with the Freundlich model, the Langmuir model was more suitable for fitting the adsorption data of Pb(Ⅱ) on two types of biocharsi.e peanut shell biocarsand pine biochars. The peanut shell biocars prepared at 200℃ had maximum adsorption capacityon Pb(Ⅱ). The process of Pb(Ⅱ) adsorption by biocharswas spontaneous, the adsorption stability of peanut shell biocars was stronger than pine biochars, and the adsorption stability decreased as pyrolysis temperature increased. When the concentration of citric acid and oxalic acid was below 2.60×10-2mmol/L and7.65×10-2mmol/L respectively, the adsorbed organic acids would provide more binding sites for Pb(Ⅱ), thus promoting the adsorption of Pb(Ⅱ). When the concentration of organic acids increased, the internal pores of biochars may be occupied by the organic acids, which would compet for the binding sites of heavy metals and thereby inhibite the adsorption of Pb(Ⅱ) on biochars. This study will provide important basic information for systematically understanding the environmental effects of biochars, and will help to comprehensively evaluate the function of biochars in environmental remediation in the presence of organic acids.
Ozaki T, Kimura T, Ohnuki T, et al. Associationmechanisms of Europium (Ⅲ) and Curium (Ⅲ) with Chlorella vulgaris[J]. Environmental Toxicology and Chemistry, 2003,22:2800-2805.
[2]
Wang Z, Liu G, Zheng H, et al. Investigating the mechanisms of biochar's removal of lead from solution[J]. Bioresource Technology, 2015,177:308-317.
[3]
Järup L. Hazards of heavy metal contamination[J]. British Medical Bulletin, 2003,68(1):167-182.
[4]
Lu H L, Zhang W H, Yang Y X, et al. Relative distribution of Pb2+ sorption mechanisms by sludge-derived biochar[J]. Water Research, 2012,46:854-862.
[5]
Ijagbemi C O, Baek M-H, Kim D-S. Montmorillonite surface properties andsorption characteristics for heavy metal removal from aqueous solutions[J]. Journal of Hazardous Materials, 2009,166(1):538-546.
[6]
Chen X C, Chen G C, Chen L G, et al. Adsorption of copper and zinc by biochars produced from pyrolysis of hardwood and corn straw in aqueous solution[J]. Bioresour Technology, 2011,102():8877-8884.
[7]
Hansen H K, Arancibia F, Gutiérrez C. Adsorption of copper onto agriculture waste materials[J]. Journal of Hazardous Materials, 2010,180:442-448.
[8]
Fischer L, Brümmer G W, Barrow N J. Observations and modeling of the reactions of 10metals with goethite:adsorption and diffusion processes[J]. European Journal of Soil Science, 2007,58:1304-1315.
[9]
Hansen H, Arancibia F, Gutiérrez C. Adsorption of copper onto agriculture waste materials[J]. Journal of hazardous materials, 2010, 180:442-448.
[10]
Li H, Dong X, Silva EBd, et al. Mechanisms of metal sorption by biochars:Biochar characteristics and modifications[J]. Chemosphere, 2017,178:466-478.
[11]
Silva G d, Ghani W A W A K, Mohd D A, et al. Biochar production from waste rubber-wood-sawdust and its potential use in C sequestration:Chemical and physical characterization[J]. Industrial Crops and Products, 2013,44:18-24.
[12]
Zheng H, Wang Z, Zhao J, et al. Sorption of antibiotic sulfamethoxazole varies with biochars produced at different temperatures[J]. Environmental Pollution, 2013,181:60-67.
[13]
李力,陆宇超,刘娅,等.玉米秸秆生物炭对Cd() Ⅱ 的吸附机理研究[J]. 农业环境科学学报, 2012,11:2277-2283. Li L, Lu Y C, Liu Y, et al. Adsorption mechanisms of cadmium() Ⅱ on biochars derived from corn straw[J]. Journal of Agro-Environment Science, 2012,11:2277-2283.
[14]
Prendergast-Miller M, Duvall M, Sohi S. Biochar-root interactions are mediated by biochar nutrient content and impacts on soil nutrient availability[J]. European Journal of Soil Science, 2014,65(1):173-185.
[15]
Jones D L, Nguyen C, Finlay R D. Carbon flow in the rhizosphere:carbon trading at the soil-root interface[J]. Plant and Soil, 2009, 321(1/2):5-33.
[16]
孟昭福,张院民,邓晶.草酸对不同土壤中Cd、Zn吸附及其交互作用影响的初步研究[J]. 农业环境科学学报, 2011,30(11):2265-2270. Meng Z F, Zhang Y M, Deng J. Effects of Oxalic Acid on the adsorption and interaction of Cd2+, Zn2+ in different soils[J]. Journal of Agro-Environmental Protection, 2011,(11):2265-2270.
[17]
Alozie N, Heaney N, Lin C. Biochar immobilizes soil-borne arsenic but not cationic metals in the presence of low-molecular-weight organic acids[J]. Science of The Total Environment, 2018,630:1188-1194.
[18]
马锋锋,赵保卫,刁静茹.小麦秸秆生物炭对水中Cd2+的吸附特性研究[J]. 中国环境科学, 2017,37(2):551-559. Ma F F, Zhao B W, Diao J R. Adsorptive characteristics of cadmium onto biochar produced from pyrolysis of wheat straw in aqueous solution[J]. China Environmental Science, 2017,37(2):551-559.
[19]
余琴芳,吕凡,於进,等.污泥生物炭在污泥好氧降解中的原位应用[J]. 中国环境科学, 2016,36(6):1794-1801. Yu Q F, Lü Fan, Yu J, et al. In-situ application of sludge-derived biochar in aerobic biodegradation of sludge[J]. China Environmental Science, 2016,36(6):1794-1801.
[20]
张尚毅,刘国涛,谢梦佩.有机垃圾热解炭对紫色土细菌群落结构的影响[J]. 中国环境科学, 2017,37(2):669-676. Zhang S Y, Liu G T, Xie M P. Influence of organic fraction of municipal solid waste-based biochar on microbial community structure in a purple soil[J]. China Environmental Science, 2017,37(2):669-676.
[21]
Xu X, Cao X D, Zhao L, et al. Removal of Cu, Zn, and Cd from aqueous solutions by the dairy manure-derived biochar[J]. Environmental Science and Technology, 2013,20:358-368.
[22]
刘德军,邵志刚,高连兴.花生壳挤压碎裂力学特性实验[J]. 沈阳农业大学学报, 2012,43(1):81-84. Liu D J, Shao Z G, Gao L X. Experimental research of the peanut shell pulverizing mechanical characteristics[J]. Journal of Shenyang Agricultural University, 2012,43(1):81-84.
[23]
Chun Y, Sheng G, Chiou C, et al. Compositions and sorptive properties of crop residue-derived chars[J]. Environmental Science and Technology, 2004,38(17):4649-4655.
[24]
Cao X, Harris W. Properties of dairy-manure-derived biochar pertinent to its potential use in remediation[J]. Bioresource Technology, 2010,101:5222-5228.
[25]
Park J, Lee Y, Ryu C, et al. Slow pyrolysis of rice straw:Analysis of products properties, carbon and energy yields[J]. Bioresource Technology, 2014,155(63-70).
[26]
郜礼阳,邓金环,唐国强,等.不同温度桉树叶生物炭对Cd2+的吸附特性及机制[J]. 中国环境科学, 2018,38(3):1001-1009. Gao L Y, Deng J H, Tang G Q, et al. Adsorption characteristics and Mechanism of Cd2+ on biochar with different pyrolysis temperatures produced from eucalyptus leaves[J]. China Environmental Science, 2018,38(3):1001-1009.
[27]
Pan B, Xing B S. Adsorption kinetics of 17alpha-ethinyl estradiol and bisphenol A on carbon nanomaterials. I. Several concerns regarding pseudo-first order and pseudo-second order models[J]. Journal of Soils and Sediments, 2010,10:838-844.
[28]
刘博,李亚东,吴林,等.不同基质条件下越橘根系分泌物中有机酸组分与含量的分析[J]. 吉林农业大学学报, 2009,31(5):581-583,594. Liu B, Li Y D, Wu L, et al. Effect of applying different substrates on ingredient and content of organic acid in blueberry root exudates[J]. Journal of Jilin Agricultural University, 2009,31(5):581-583,594.
[29]
Yuan J H, Xu R K, Zhang H. The forms of alkalis in the biochar produced from crop residues at different temperatures[J]. Bioresource Technology, 2011,102(3):3488-3497.
[30]
Keiluweit M, Nico P S, Johnson M G, et al. Dynamic molecular structure of plant biomass-derived black carbon (Biochar)[J]. Environmental Science Technology, 2010,44(4):1247-1253.
[31]
Wang Z Y, Zheng H, Luo Y, et al. Characterization and influence of biochars on nitrous oxide emission from agricultural soil[J]. Environmental Pollution, 2013,174:289-296.
[32]
Chen B L, Zhou D D, Zhu L Z. Transitional adsorption and partition of nonpolar and polar aromatic contaminants by biochars of pine needles with different pyrolytic temperatures[J]. Environmental Science and Technology, 2008,42(14):5137-5143.
[33]
Zheng H, Wang Z Y, Zhao J, et al. Sorption of antibiotic sulfamethoxazole varies with biochars produced at different temperatures[J]. Environmental Pollution, 2013,181:60-67.
[34]
Bustin R M, Guo Y. Abrupt changes (jumps) in reflectance values and chemical compositions of artificial charcoals aninertinite in coals[J]. International Journal of Coal Geology, 1999,38:237-260.
[35]
吴成,张晓丽,李关宾.低分子量有机酸对黑碳吸附Pb、Cd的影响[J]. 农业环境科学学报, 2006,25(5):1383-1387. Wu C, Zhang X L, Li G B. Effect of low molecular weight organic acids on Pb2+ and Cd2+ adsorption of black carbon[J]. Journal of Agro-Environment Science, 2006,25(5):1383-1387.
[36]
徐仁扣,肖双成,季国亮.低分子量有机酸影响可变电荷土壤吸附铜的机制[J]. 中国环境科学, 2005,25(3):334-338. Xu R K, Xiao S C, Ji G L. Mechanism of low molecular weight organic acids affecting Cu adsorption by variable charge soils[J]. China Environmental Science, 2005,25(3):334-338.
[37]
周丹丹,梁妮,李浩,等.小分子有机酸对生物炭吸附Cu(Ⅱ)的影响[J]. 农业环境科学学报, 2016,35(10):1923-1930. Zhou D D, Liang i, Li H, et al. Effect of low molecular weight organic acids on Cu(Ⅱ) adsorption by biochars[J]. Journal of AgroEnvironmental Protection, 2016,35(10):1923-1930.
[38]
Li X Y, Pignatello J J, Wang Y Q, et al. New insight into adsorption mechanism of ionizable compounds on carbon nanotubes[J]. Environmental Science and Technology, 2013,47(15):8334-8341.
[39]
Zhu B, Fan T X, Zhang D. Adsorption of copper ions from aqueous solution by citric acid modified soybean straw[J]. Journal of Hazardous Materials, 2008,153:300-308.
[40]
Feng Y, Dionysiou D D, Wu Y H, et al. Adsorption of dyestuff from aqueous solutions through oxalic acid-modified swede rape straw:Adsorption process and disposal methodology of depleted bioadsorbents[J]. Bioresource Technology, 2013,138:191-197.
