Abstract
The widespread use and negative environmental effects of antibiotics have made their removal from aqueous media essential in terms of wastewater treatment. Accordingly, a hybrid helical Cu@Cu2O@CuO–microalgae photocatalyst for antibiotic photodegradation was synthesized in this study by a simple, inexpensive, and scalable process based on electroless Cu deposition and soft thermal treatment. The hybrid photocatalyst was more competitive for the photocatalytic degradation of tetracycline, especially in terms of mineralization and energy consumption, than state-of-the-art photocatalysts. The excellent photocatalytic performance is attributable to the effective formation of onion-like Cu@Cu2O@CuO heterojunctions, which synergistically lower the electron–hole recombination rate, promote the utilization of light and photogeneration of charge carriers, and decrease the photocorrosion activity. All these effects result in the enhanced photocatalytic degradation and mineralization of tetracycline. The high photocatalytic performance of the Cu@Cu2O@CuO–microalgae hybrids under LED irradiation resulted in a significantly lower electrical energy per order—i.e., the electrical energy required to diminish the tetracycline concentration by one order of magnitude in a unit of volume—of 57 kW h m−3 order-1. Importantly, the Cu@Cu2O@CuO–microalgae hybrids can easily be recycled after reaching their effective lifetime to fabricate competitive microalgal pellets, then integrated into a circular process in an environment–energy nexus to minimize the generation of residues.
Highlights
Over the past several decades, the dumping of antibiotics into ponds, canals, lakes, rivers, and other bodies of water has caused considerable concerns regarding their unknown environmental impacts and potential damage to aquatic biota [1,2,3,4]
The microalgae hybrid photocatalyst consisted of A. platensis, which acts as a structural support, covered with an onion-like Cu@Cu2O@CuO multilayered shell
The onion-like Cu@Cu2O@CuO–microalgae hybrid photocatalyst was synthesized by a simple biotemplating process based on (i) copper electroless deposition, which generates a smooth Cu metallic layer (>95% in content), followed by (ii) a copper oxidation process via a simple annealing treatment at 200 ◦C for 8 h in an air atmosphere [35]
Summary
Over the past several decades, the dumping of antibiotics into ponds, canals, lakes, rivers, and other bodies of water has caused considerable concerns regarding their unknown environmental impacts and potential damage to aquatic biota [1,2,3,4]. Tetracyclines are the second most consumed family of antibiotics in the world owing to their low cost, easy synthesis, and favorable antimicrobial activity based on the inhibition of protein synthesis [11,12] This family of antibiotics is mainly used for the therapy and prophylaxis of human infections (e.g., atypical pneumonia, cholera, pelvic inflammations, granuloma inguinal, periodontal infection, acne vulgaris, etc.); the treatment of animal in fections in veterinary medicine (e.g., poultry, sheep, swine, etc.); as animal growth promoters to improve growth rates and feed conversion efficiency, which directly translate into an important reduction in food consumption to reach marketable weight; and to control infections in aquaculture (e.g., salmon, catfish), botany (e.g., fruit trees, seeds), and. This work contributes to the fabrica tion of efficient, recyclable, green, and low-cost core@shell@shell Cu@Cu2O@CuO–microalgae photocatalysts to replace today’s linear “take–make–dispose” thinking with circular processes with the final aim of facilitating the applicability of photocatalysts to water decontamination
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