摘要
垃圾焚烧飞灰中Pb和Cd对人体及环境危害极大且浸出质量浓度严重超标。为稳定飞灰中的Pb和Cd,合成了一种以玉米淀粉为主体的有机螯合剂,用于处理飞灰中的Pb和Cd。通过改变螯合剂投加质量分数、养护时间、液固比(mL∶g)和pH值来研究螯合剂稳定效果并进行表征。X射线衍射(X-ray Diffraction,XRD)结果显示,改性处理未改变玉米淀粉的结晶结构类型。通过对结晶度计算,表明改性过程发生在淀粉结晶区。扫描电镜(Scanning Electron Microscope,SEM)结果显示,处理前飞灰比表面积较大,飞灰经过改性玉米淀粉处理后粒径明显增大,降低了飞灰比表面积。通过傅里叶变换红外(Fourier Transform Infrared,FT-IR)光谱表征,显示飞灰处理前后主要存在碳酸盐、硫酸盐和硅铝酸盐。采用单因素试验确定改性淀粉螯合飞灰Pb和Cd的最佳条件为:改性淀粉投加质量分数为3%、养护时间为24 h、液固比(mL∶g)为2∶5、pH值为7~9。该条件下,Pb和Cd浸出质量浓度最低分别为0.162 mg/L、0.087 mg/L,对Pb和Cd稳定化率均大于93%,浸出质量浓度远低于《生活垃圾填埋场控制标准》限值。淋溶试验显示,淋溶速率较慢及酸雨条件下,螯合体中Pb和Cd的溶解程度较高。
The research adopts the synthesis method of a kind of inverse emulsion with corn starch as the main body of the organic chelating agent to deal with Pb and Cd in fly ash.The effect of the chelating agent on stabilizing Pb and Cd in fly ash is studied by changing the proportion of the chelating agent,curing time,liquid-solid ratio,and pH value,and the chelating agent and chelating compound are characterized.X-ray Diffraction(XRD)analysis by the chelating agent shows that the crystal structure type of corn starch is not changed by modification.The crystallinity of the chelating agent decreases by 8.15%compared with that of unmodified corn starch,indicating that the modification process occurs in the crystal zone of starch and destroys part of the intramolecular hydrogen bond.The chelate Scanning Electron Microscope(SEM)shows that the specific surface area of fly ash is larger before treatment,the particle size of fly ash is significantly increased after treatment with modified corn starch,and the specific surface area of fly ash is decreased.The chelate was characterized by Fourier Transform Infrared(FT IR)spectra,which indicates that carbonates,sulfates,and silicoaluminate exist before and after fly ash treatment.The optimum conditions for chelating Pb and Cd of fly ash with modified starch are determined by single factor experiment:When the modified starch is added with 3%,curing time for 24 h,liquid-solid ratio(mL∶g)2∶5 and pH value 79,the lowest leaching mass concentrations of Pb and Cd were 0.162 mg/L and 0.087 mg/L,and the stabilization rates for Pb and Cd are greater than 91%and 92%respectively.Pb and Cd leaching concentrations are much lower than the limits of the"Landfill Control Standard".The results of leaching experiments show that Pb and Cd in chelate are dissolved in a higher degree under a slower leaching rate and acid rain.
作者
国洁
冉祥明
王欣
赵晓曼
GUO Jie;RAN Xiangming;WANG Xin;ZHAO Xiaoman(School of Environmental Science and Engineering,Hebei University of Science and Technology,Shijiazhuang 050018,China;Pollution Prevention Biotechnology Laboratory of Hebei Province,Shijiazhuang 050018,China)
出处
《安全与环境学报》
CAS
CSCD
北大核心
2024年第5期2006-2016,共11页
Journal of Safety and Environment
基金
河北省自然科学基金项目(B20202080023)。
关键词
环境工程学
高分子螯合剂
垃圾焚烧
飞灰
重金属
稳定化
environmental engineering
high molecular chelating agent
waste incineration
fly ash
heavy metal
stabilization
