| Abstract: | The use of biochars formed by hydrothermal carbonization for the treatment of contaminated water has been greatly limited,due to their poorly developed porosity and low content of surface functional groups.Also,the most common modification routes inevitably require post-treatment processes,which are time-consuming and energy-wasting.Hence,the objective of this research was to produce a cost-effective biochar with improved performance for the treatment of heavy metal pollution through a facile one-step hydrothermal carbonization process coupled with ammonium phosphate,thiocarbamide,ammonium chloride or urea,without any posttreatment.The effects of various operational parameters,including type of modification reagent,time and temperature of hydrothermal treatment,and ratio of modification reagent to precursor during impregnation,on the copper ion adsorption were examined.The adsorption data fit the Langmuir adsorption isotherm model quite well.The maximum adsorption capacities(mg/g) of the biochars towards copper ions followed the order of 40-8 h-1.0-APBC(95.24) 140-8 h-0-BC(12.52) 140-8 h-1.0-TUBC(12.08) 140-8 h-1.0-ACBC(7.440) 140-8 h-1.0-URBC(5.277).The results indicated that biochars modified with ammonium phosphate displayed excellent adsorption performance toward copper ions,which was 7.6-fold higher than that of the pristine biochar.EDX and FT-IR analyses before and after adsorption demonstrated that the main removal mechanism involved complexation between the phosphate groups on the surface of the modified biochars and copper ions. |
