Construction of engineered heterojunction based on CdS and MgO material co-integrated into a flat plane-like graphene for tetracycline decontamination: Ecological hazard assessment and toxicity alleviation

Abstract

This study encompasses the photocatalytic decomposition activity of an appreciable ternary CdS/MgO/graphene heterostructured composite (denoted as CMG) for the decontamination of recalcitrant tetracycline (TTC) from aqueous environment under LED light illumination. The physicochemical characteristics of the as-prepared catalysts were elucidated utilizing a series of advanced analytical methods including XRD, FTIR, DRS, BET, EIS, TEM, and FESEM. The CMG architectures reveal vigorous photocatalytic performance towards the decontamination of TTC upon exposure to the LED light, the decontamination rate is approximately 5.5, 4 and 3 times higher than neat graphene, MgO and CdS, respectively. Under the optimized conditions (i.e., pH: 7, CMG dosage: 0.5 g. L⁻¹, light intensity: 75 W and TTC content: 30 mg. L⁻¹), the remarkable degradation rate of TTC (98 % in 120 min) was achieved by the CMG/LED system. An inhibitory impact of anions during the photocatalyst process was recorded as follows: Cl⁻ > NO³⁻ > SO₄²⁻ > PO₄³⁻. To provide a comprehensive understanding of the photocatalyst's behavior and shed light on its mechanism, various analytical techniques were utilized including band structure evaluation, EIS, and capture experiments. The active agents trapping experiments evidenced that OH radicals are the predominant decomposing agents participated in the TTC decontamination. Furthermore, the CMG composite exhibited a noticeable performance during six cycling treatment experiments, inducing its remarkable capability for practical applications. The photocatalytic mechanism of the TTC degradation route over the CMG/LED system was unraveled on the basis of the LC-MS analysis. The ECOSAR software calculations forecasted that CMG/LED system could be regarded as an ecologically benign technology to eliminate antibiotic-related hazards to the living individuals and the environment. In extension, the ecological risk assessment of TTC and its intermediates was scrutinized over CMG/LED system for the first time ever, revealing the excellent performance of the target system in diminishing the actual potential ecological risk.