Preparation and Pyrolysis Kinetics of Phenolic Resins of Main Phenols in Semi-coking Wastewater

WANG Yali†, WANG Yufei, LI Jian, PENG Jiajia, CAO Shuai, YAN Long†

School of Chemistry and Chemical Engineering, Yulin University, Yulin 719000; † Corresponding authors, E-mail: yaw32@yulinu.edu.cn (WANG Yali), 175526421@qq.com (YAN Long)

Abstract The composition and concentration of organic compounds in semi-coking wastewater were determined by GC-MS. The mixtures of a few of the five most representative phenolic substances (phenol, m-cresol, 2,3dimethylphenol, catechol and 2,6-dimethylphenol) were utilized to simulate semi-coking wastewater. Phenolic resins in the simulated semi-coking wastewater were prepared in the presence of formaldehyde. The phenolic resins were characterized by in-situ infrared and thermal analysis. The pyrolysis kinetic parameters obtained from analyzing thermogravimetric analysis data indicated that a mixture of phenolic compounds had higher crosslinking degree and the phenolic resin was more stable. This study provides a theoretical basis for optimizing of semicoking wastewater treatment by utilizing formaldehyde. Key words semi-coking water; phenolic compounds; phenolic resins; pyrolysis kinetics

榆林兰炭年产能为5000万吨, 占全国兰炭产业的一半, 是地方经济发展的重要支柱之一。然而,榆林兰炭生产中重大难题之一是每年产生的近1亿m3高毒有机含酚废水的处理[1]。以废制废、变废为宝、资源化利用是国家对污染性工业发展的基本政策[2–3], 对榆林兰炭产业同样适用。现阶段对兰炭生产中的有机含酚废水处理仍然停留在酚类物质的萃取回收[4]。由于兰炭废水的成分复杂, 后续工艺流程长, 萃取得到的酚类物质通常焚烧处理, 或作为杂酚进行销售, 存在严重

的二次污染问题。朱慎林等[5]报道的 DMC萃取法,可将含酚废水中的酚含量从5000 mg/l降到4.8 mg/ L。马亚军等[6]、闫龙等[7]和谢钢等[8]将甲醛加入兰炭废水, 把酚类物质转化为酚醛树脂。若以常见的兰炭废水酚类物质含量3000 mg/l[9]计算, 即使兰炭废水中一半的酚转化为酚醛树脂, 每年至少可产生200万吨酚醛树脂。但是, 该方法生成的酚醛树脂成分复杂, 难以直接利用, 若要进一步提高产品质量, 有必要研究甲醛与兰炭废水中酚类物质的作用机制。