Key Takeaways & Executive Findings
- •• • MF/Fe-C/PS achieved 99% degradation of CGA within 60 min under optimal conditions (pH=3, PS=1.5 mmol·L−1, Fe-C=0.4 g·L−1), demonstrating near-complete removal of a recalcitrant pharmaceutical pollutant. • • Radical contribution rates were quantified: SO4−· (41.6%), ·OH (30.5%), and 1O2 (27.9%), enabling targeted optimization of oxidant systems for enhanced performance. • • The presence of Cl−, Br−, and I− inhibited CGA degradation, with the effect varying by halide; this highlights the need for pre-treatment in saline or halide-rich waters. • • MF/Fe-C/PS pre-oxidation significantly reduced the formation potential of THMs and HANs during subsequent chlorination/chloramination, mitigating disinfection byproduct risks. • • The process exhibited an energy consumption of 3.38 kW·h·m−3 (EE/O), indicating superior energy efficiency compared to Fe-C, PS, and Fe-C/PS alone, supporting its economic viability for water treatment.
Abstract
Chlorogenic acid (CGA), a key component of the anti-COVID drug Lianhua Qingwen, is recalcitrant to biodegradation and tends to bioaccumulate, posing risks to aquatic ecosystems. Conventional water treatment methods are inadequate for its removal. This study investigated the degradation of CGA using a magnetic field coupled Fe-C activated persulfate (MF/Fe-C/PS) advanced oxidation process. The degradation efficiencies of Fe-C, PS, Fe-C/PS, and MF/Fe-C/PS systems were compared, and the dominant reactive species and their contributions were identified. The effects of initial pH, persulfate (PS) concentration, Fe-C dosage, and inorganic anions on degradation kinetics were examined, along with the degradation pathway and disinfection byproduct (DBP) formation potential. Results showed that MF/Fe-C/PS achieved 99% degradation of CGA within 60 min under optimal conditions: pH=3, PS concentration 1.5 mmol·L−1, and Fe-C dosage 0.4 g·L−1. Coexisting Cl−, Br−, and I− inhibited CGA oxidation to varying degrees, as did natural organic matter (FA and BAS). The reactive species SO4−·, ·OH, and 1O2 contributed 41.6%, 30.5%, and 27.9%, respectively. Degradation mechanisms included hydrolysis, dehydroxylation, decarboxylation, and benzene ring cleavage. Pre-oxidation by MF/Fe-C/PS significantly reduced the DBP formation potential during subsequent chlorination/chloramination. Energy per order (EE/O) analysis indicated favorable economic efficiency.
1. Introduction
Chlorogenic acid (CGA), a bioactive compound in herbal medicines, enters water bodies through pharmaceutical manufacturing and human excretion. Its resistance to biodegradation and potential for bioaccumulation necessitate advanced oxidation processes (AOPs) for effective removal. Conventional treatments such as activated carbon adsorption or biological degradation are often inefficient or produce secondary waste. Persulfate-based AOPs generate sulfate radicals (SO4−·) and hydroxyl radicals (·OH) capable of oxidizing recalcitrant organics, but their application is limited by slow kinetics and high reagent consumption.
This study introduces a magnetic field (MF) coupled with Fe-C bimetallic particles to activate persulfate (PS), enhancing radical generation and mass transfer. The MF/Fe-C/PS system addresses the bottleneck of slow Fe2+ regeneration and limited radical production in conventional Fe-C/PS processes. By systematically evaluating degradation efficiency, radical contributions, and DBP formation potential, the research provides a comprehensive assessment of a promising technology for CGA removal, with implications for pharmaceutical wastewater treatment and drinking water safety.
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QU Hui, LU Xian, CHANG Tao, TAO Jun, ZHAO Zhimiao, ZHANG Yinjiang (2026). Degradation of Chlorogenic Acid by Magnetic Field Coupled Fe-C Activated Persulfate Process. Environmental Chemistry. https://doi.org/10.7524/j.issn.0254-6108.2025032704
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Frequently Asked Questions
What is the optimal operating pH for the MF/Fe-C/PS system, and how does pH affect degradation efficiency?
The optimal pH is 3.0, achieving 99% degradation within 60 minutes. At higher pH, degradation efficiency decreases due to reduced radical generation and potential iron precipitation.
How do coexisting halide ions (Cl−, Br−, I−) impact the degradation of CGA, and what are the implications for real water matrices?
All three halides inhibit CGA degradation, with the extent varying: Cl− and Br− show moderate inhibition, while I− causes significant suppression. This is likely due to scavenging of SO4−· and ·OH and formation of less reactive halogen radicals. In halide-rich waters, pre-treatment or higher oxidant doses may be required.
What are the main reactive species responsible for CGA degradation, and what are their relative contributions?
The primary reactive species are SO4−·, ·OH, and 1O2, with contributions of 41.6%, 30.5%, and 27.9%, respectively. This was determined via quenching experiments, indicating a mixed radical/non-radical pathway.
How does the MF/Fe-C/PS process affect the formation potential of disinfection byproducts (DBPs) during subsequent chlorination?
Pre-oxidation by MF/Fe-C/PS significantly reduces the formation potential of trihalomethanes (THMs) and haloacetonitriles (HANs) during chlorination/chloramination, likely by transforming CGA into less reactive intermediates. This is crucial for meeting drinking water DBP regulations.
What is the energy consumption of the MF/Fe-C/PS process, and how does it compare to other systems?
The energy per order (EE/O) for MF/Fe-C/PS is 3.38 kW·h·m−3, which is lower than that of Fe-C/PS, Fe-C, and PS alone, indicating better energy efficiency and economic feasibility for large-scale application.
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