Salicylic acid-methanol modified steel converter slag as heterogeneous Fenton-like catalyst for enhanced degradation of alachlor

- SAM treatment significantly improved the catalytic property of steel slag.
- SAM can selectively dissolve calcium silicate minerals on the surface of steel slag.
- SAM modified slag shows high activity and good reusability for alachlor degradation.
- The degradation rate decreased along with the increase of initial pH from 2 to 6.0.

Significant effort has recently been directed toward the use of advanced oxidation processes (AOPs) to degrade organic pollutants. In this work, an affordable and effective heterogeneous Fenton-like process was proposed and studied. Preparation and utilization of an iron-rich catalyst, salicylic acid-methanol (SAM) modified steel converter slag (SCS), were investigated for the degradation of alachlor in wastewater. Brunauer-Emmett-Teller (BET), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), Fourier transform infrared (FT-IR), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) were used to assess the morphology and crystal structure of the prepared catalysts. Results showed that SAM modification can selectively remove calcium silicate minerals from surface of SCS. The modification decreased the alkalinity of SCS and led to a prominent decrease in the specific surface areas and iron content, which dramatically improved the catalytic property of SCS. The removal rate of alachlor at initial pH 3.0 in SAM-modified SCS/H2O2 system was 3.07 times of that in SCS/H2O2 system. Further studies showed that this heterogeneous Fenton-like process was more suitable to be performed at relative higher temperature (30-40 °C) and lower initial pH (2.0-3.0). A small decrease (2.1%) was found in the activity of SAM-modified SCS after four runs, indicating a feasible way to utilize SCS and also achieve excellent environmental benefit.

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