Journal of Shandong University(Engineering Science) ›› 2026, Vol. 56 ›› Issue (5): 201-214.doi: 10.6040/j.issn.1672-3961.0.2025.162

• Environment Engineering • Previous Articles    

Mechanistic study on the effect of carbonate on the degradation of trimethoprim in UV/H2O2

Wei Fenghua1, Wang Chenglin2, Gu Qingyuan2, He Maoxia2*   

  1. Wei Fenghua1, Wang Chenglin2, Gu Qingyuan2, He Maoxia2*(1. Assets and Laboratory Management Office, Shandong University(Qingdao), Qingdao 266237, Shandong, China;
    2. Environment Research Institute, Shandong University, Qingdao 266237, Shandong, China
  • Published:2026-10-19

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Abstract: To elucidate the regulatory mechanisms and pH dependence of carbonates in the UV/H2O2 degradation of trimethoprim(TMP), theoretical calculation methods were adopted to study the differences in the initial reaction mechanisms of TMP with CO·-3 and HO· under UV/H2O2 conditions, as well as the influence mechanism of carbonates on their reaction mechanisms. The research results showed that CO·-3 had strong selectivity for molecules in different dissociation forms(neutral, diprotonated and monoprotonated forms of TMP), and only underwent single electron transfer reaction(SET)with neutral TMP. Compared with the HO· system, its SET activation energy barrier was reduced by 30.98%. Therefore, compared with the multi-site hydroxylation characteristics of HO· on the benzene ring, imino and pyrimidine ring, although CO·-3 could not directly achieve the complete mineralization of TMP, it could significantly reduce the activation energy of the subsequent reaction of HO· by generating a radical cation intermediate. There was a threshold effect in carbonate concentration. At low concentrations, carbonate acted as an electron transfer medium between HO· and TMP, which could accelerate the degradation of TMP. High concentrations, on the other hand, exhibited a quenching effect on HO· and inhibited degradation. Toxicity assessment of the intermediate products indicates that, with the exception of P12, the toxicity of most hydroxylated and carbonylated intermediates is lower than that of the parent compound. Carbonate showed a concentration-dependent effect during UV/H2O2 degradation of TMP, low concentrations promoted TMP degradation via CO·-3-mediated electron transfer, whereas high concentrations inhibited it by quenching HO·

Key words: synthetic antimicrobial, pH, carbonate, UV/H2O2, degradation mechanism, degradation efficiency

CLC Number: 

  • X131.2
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