Application of mixture experimental design for photocatalytic ammonia degradation by sunlight‐driven WO ₃ ‐Ag ₃ PO ₄ ‐ZnO ternary photocatalysts

Abstract

Summary Using statistical mixture design, the best composition of a heterojunction photocatalyst containing ZnO, Ag3PO4, and WO3 was determined to maximize the sunlight driven ammonia removal from aqueous solution via both photocatalysis and adsorption processes. All samples were prepared by coprecipitation and immobilized over perlite granules as floatable support. X‐ray diffraction (XRD), Fourier‐transform infrared (FTIR), field emission scanning electron microscope (FESEM), Brunauer, Emmett, and Teller (BET), ultraviolet–visible (UV‐vis), and photoluminescence (PL) analyses were used to characterize the catalysts. Three responses of ammonia removal by photocatalysis, adsorption, and the total ammonia removal were modeled by special cubic models, and the ANOVA confirmed the significance of them. The maximum ammonia removal, approximately 88%, was obtained by photocatalyst composed of 32.93‐wt% WO3, 41.82‐wt% Ag3PO4, and 25.26‐wt% ZnO. The contribution of photocatalysis and adsorption was estimated to be 72.74% and 14.44%, respectively, indicating the dominance of photocatalysis process. According to kinetic study, the optimum photocatalyst showed the highest apparent rate constant and lowest half‐life time of ammonia removal. The maximum quantum yield of 1.7% was calculated from the best photocatalyst composite at the maximum intensity of visible light received from sunlight. The reuse ability test revealed that the optimum ternary photocatalyst is suitable for wastewater treatments in practical applications.

Band gap tuning of BaFe 12 O 19 with Mg and Mn doping to enhance solar light absorption for photocatalytic application

“…This disorder is more prominent in the lower energy range of the band gap, where bending of the band occurs due to interactions of valance band holes, conduction band electrons, and dopant ions 43 . Due to the low band gap, the higher absorption property of visible light of Ba 1−x Mg x Fe 12−y Mn y O 19 could highly useful be in various potential applications in optoelectronic devices, solar devices, sensors, transistors, LED, photovoltaic, spintronic, gamma ray detectors, and photo‐catalysis 6‐8,44,45 …”

“…Owing to various physico‐chemical properties, for example, high surface to volume ratio as compared to the bulk material, the nanoparticles (NPs) showed promising applications in photocatylsis, energy conservation, energy storage devices, sensors, food, imaging, therapeutic, and electronic devices 1‐4 . Semiconductor metal oxides‐based NPs with appropriate band gap energies absorb radiation in the visible region and revealed higher stability and charge separation, which finds promising applications in diverse fields 5‐9 . In comparison to other metal semiconductor metal oxides, the ferrite is a class of magnetic metal oxides with unique optical, electronic, and catalytic properties.…”

Preparation of floatable TiO 2 /poly(vinyl alcohol)‐alginate composite for the photodegradation of ammonia wastewater

“…In the last few decades, photocatalysis has been considered as a favorable and reliable remediation strategy for the degradation of ammonia wastewater. By photocatalysis, ammonia wastewater can be decomposed into N 2 , H 2 , and low concentration NO 2 and NO 3 through nitrification process . Generally, photocatalysis has many pros and cons in usage, for instance, it is a low‐cost, no toxicant, and high‐efficiency method without generation of secondary pollution, but the need for agitation to avoid photocatalyst sedimentation and also separation of photocatalyst particles as a posttreatment process have restricted the practical applications of it.…”