High activity nitrogen and sulfur co-doping high specific surface-modified peanut shell carbon PBC-NS was prepared through one-step carbonization using thiourea and phosphoric acid as modifiers. The TC/Cu(Ⅱ) adsorption characteristics of peanut shell carbon in single and mixed-adsorption systems were discussed, and the enhancement effect and mechanism of modification on TC/Cu(Ⅱ) adsorption were studied. The results showed that the modified peanut shell carbon PBC-NS successfully introduced nitrogen-sulfur functional groups such as Pyridinic N, Graphitic N, C- S-C, and -SH, and the modified specific surface area was as high as 1437 m2·g-1, which was 2.6 times higher than that before modification. The maximum adsorption capacities of modified peanut shell carbon PBC-NS for single-system TC and Cu(Ⅱ) were 585 mg·g-1 and 21.2 mg·g-1, respectively, which were 2.6 times and 2.7 times higher than those before modification. The saturated adsorption capacities of TC and Cu(Ⅱ) in the system were increased by 13 mg·g-1 and 6.8 mg·g-1 compared with that in the single system. The adsorption capacity of PBC-NS for TC and Cu(Ⅱ) could still reach 66% and 70% of the initial adsorption capacity after four times of repeated use. Isotherm fitting and modern spectroscopic analysis indicated that the substantial increase in the adsorption capacity of TC/Cu(Ⅱ) on PBC-NS by modification was mainly attributed to the combined effect of chemical chelation of nitrogen-sulfur active functional sites and pore filling caused by high specific surface area. These results indicated that thiourea/phosphoric acid chemical modification could effectively improve the adsorption capacity of peanut shell carbon for TC/Cu(Ⅱ), which can provide a new idea for the structural regulation of mixed-pollution biochar with high adsorption capacity and adsorption treatment of TC/Cu(Ⅱ) water pollution.
Keywords: aquaculture wastewater; enhancement; high specific surface; mixed adsorption; nitrogen and sulfur co-doping.