Degradation of sulfamethoxazole with peroxyacetic acid activated by alkali-modified sludge biochar

Abstract

Sludge biochar was prepared from municipal sewage sludge by oxygen-limited pyrolysis at 800 ℃, and modified with sodium hydroxide to obtain alkali-modified sludge biochar (N-SDBC) as a catalyst to activate peroxyacetic acid (PAA) for the degradation of sulfamethoxazole (SMX). The catalyst was characterized by SEM, FTIR, BET, and acid-base potential methods. The effects of oxidant concentration, catalyst dosage, initial pH, common anions in water, and humic acid on the degradation performance of SMX were investigated. The results showed that the degradation rate of SMX reached 83.8% in 90 minutes under the conditions of N-SDBC mass concentration of 1.5 g/L, PAA concentration of 1.0 mmol/L, and initial pH of 3.0. The coexisting anions and humic acids in the water body inhibited the degradation of SMX to different degrees. The results of the bursting experiments and electrochemical tests showed that ·OH and 1O2 were the main reactive oxygen species in the system, and there was an electron transfer mechanism in the N-SDBC/PAA system for the degradation of SMX. After four reused tests, the removal rate of SMX was maintained above 70%, indicating that N-SDBC had good stability.