反应时间对污泥水热炭特性及重金属生态风险的影响

Effect of reaction time on the characteristics of sludge hydrothermal biochar and the ecological risk of heavy metals

反应时间是影响污泥水热炭(以下简称水热炭)性质的重要因素之一。通过水热炭化反应,确定了反应时间(90、180、360 min)对水热炭性质、结构及重金属生态风险的影响。结果表明,反应时间的延长促进了水热炭产率及比表面积的增加,反应时间为180 min时水热炭产率(61.4%)及比表面积(13.90 m^(2)/g)达到最大值,pH降至最低(5.95),水热炭的H/C(质量比,下同)、(O+N)/C在360 min时达到最小值。水热炭化反应大体促进了重金属(Cu、Zn、Pb、Cr、Ni)的富集及生态风险的降低。反应时间为180 min时各重金属的富集程度最高,重金属生物有效态含量及浸出毒性达到最低,Pb除外。研究表明,延长反应时间有利于提升水热炭品质及降低重金属生态风险。

Reaction time is one of the important factors affecting the hydrothermal biochar properties of sludge.This paper studied the effects of reaction time(90,180,360 min)on the properties,structure,and ecological risk of heavy metals of hydrothermal biochar.The results showed that the prolonged reaction time promoted the increase of hydrothermal biochar yield and specific surface area.When the reaction time was 180 minutes,yield(61.4%)and specific surface area(13.90 m^(2)/g)reached the maximum,and the pH reduced to the lowest(5.95),the H/C(mass ratio,the same below),(O+N)/C of hydrothermal biochar reached the minimum value at 360 min.Hydrothermal carbonization generally promoted the enrichment of heavy metals(Cu,Zn,Pb,Cr,Ni)and reduced the ecological risk.When the reaction time was 180 min,the enrichment degree of each heavy metal was the highest,and the bioavailable content of heavy metals and the leaching toxicity reached the lowest value,except for Pb.This study showed that prolonging the reaction time was beneficial to improve the quality of hydrothermal biochar and reduce the ecological risk of heavy metals.