改性油菜秸秆生物质炭吸附/解吸Cd2+特征  

Characteristics of Cd2+ sorption/desorption of modified oilrape straw biochar

作　　者：陈雪娇[1] 林启美[1,2] 肖弘扬 Muhammad Rizwan 赵小蓉 李贵桐[1,2] Chen Xuejiao;Lin Qimei;Xiao Hongyang;Muhammad Rizwan;Zhao Xiaorong;Li Guitong(College of Resources and Environmental Sciences,China Agricultural University,Beijing 100193,China;Key Laboratory of ArableLand Conservation (North China),Ministry of Agriculture/Key Laboratory of Plant-Soil Interactions,Ministry of Education,College ofResources and Environmental Sciences,China Agricultural University,Beijing 100193,China)

机构地区：[1]中国农业大学资源与环境学院,北京100193 [2]中国农业大学资源与环境学院,农业部华北耕地保育重点实验室,植物-土壤相互作用教育部重点实验室,北京100193

出　　处：《农业工程学报》2019年第18期220-227,共8页Transactions of the Chinese Society of Agricultural Engineering

基　　金：国家科技支撑计划(2015BAD05B03)

摘　　要：该研究选用蒸汽爆破油菜秸秆,对其进行羟基磷灰石和KMnO4浸渍处理,再用壳聚糖和NaOH溶液改性所获得的生物质炭改性,以比较表面特性变化和吸附/解吸Cd^2+的特征。结果表明,改性处理可有效地在生物质炭表面负载相应官能团,如羟基磷灰石处理使生物质炭表面磷酸盐增多,比表面积提高至225.68m^2/g;而壳聚糖、KMnO4和NaOH处理,则引入了-NH2和-OH、-COOH等酸性含氧官能团。尽管改性生物质炭表面电荷减少,但Cd^2+吸附容量却提高了13%~315%,其吸附行为可用Langmuir等温吸附式拟合,并符合Pseudo second order吸附动力学方程。改性后,生物质炭对Cd^2+的吸附主要为专性吸附,其初始吸附速率提高了65%~379%,而解吸率降低了17%~91%,表明对Cd2+的吸附更快且更加稳定,具有良好的应用潜力。Biochar has recently received much attention as an adsorbent for removing pollutants. It is meaningful to develop innovative biochar with high adsorption capacity through physical, chemical and even biological processes. Based on our previous study, steam explosion was an ideal method to pretreat oil rape straw, because it enhanced the surface area of biochar by approximately 16 times, which was helpful for the adsorption as well as the further modification. In this study, steam exploded oil rape straw was soaked in hydroxyapatiteslurry and KMnO4 solution prior to biochar production. In addition, the pristine biochar was also modified by chitosan and NaOH solution. Nitrogen adsorption/desorption isotherms, scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), and Fourier transform infrared spectroscopy (FTIR), etc. were used to determine and compare the characteristics of different modified biochars, and then explore the Cd^2+ sorption/desorption mechanisms. The results showed that the elemental composition of biochar was significantly affected by the nature of the modification materials. All the modified biochar had higher H/C and O/C ratios, therefore, it had higher polarity and hydrophilicity. The surface area of biochar derived from hydroxyapatite impregnated feedstocks was 225.68 m^2/g. Chitosan, KMnO4 and NaOH modification, however, led to the decrease of surface area and pore volume by 76%-96% and 43%-84%, respectively. All these modification treatments induced in the loading of relevant materials on the biochar surface. For example, hydroxyapatite treatment resulted in the increase of phosphates, while chitosan, KMnO4 and NaOH modification introduced the acidic oxygen-containing groups such as hydroxyl (-OH), carboxyl (-COOH), and -NH2 as well. Although both positive and negative charges were reduced due to the modification treatment, the Cd^2+ adsorption capacity increased by 13%-315%, and NaOH modified biochar provided the highest value (54.12 mg/g). Batch experiment displayed that t

关 键 词：秸秆 重金属 吸附 生物质炭 改性 镉 解吸 

分 类 号：X712[环境科学与工程—环境工程] X53