Photocatalytic and adsorption behavior of a new efficient LaxNiyMn3–(x+y)O4/SiO2 composite for environmental remediation application

Abstract

Environmental remediation of organic contaminants has recently received significant attention, necessitating the development of energy-efficient, cost effective, and environment-friendly catalysts. In this study, novel dual-doped LaxNiyMn3–(x+y)O4 nanoparticles (NPs) and their composite with an adsorptive material (mesoporous silica) were synthesized using a low-cost, environment-friendly coprecipitation technique. The as-prepared LaxNiyMn3–(x+y)O4 NPs and their composite were studied via X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), Fourier-transform infrared (FTIR) spectroscopy, and ultraviolet–visible spectroscopy. XRD analysis revealed that the LaxNiyMn3–(x+y)O4 NPs possessed a crystalline structure. FESEM showed that LaxNiyMn3–(x+y)O4 NPs were spherical with diameters ranging from 60 to 100 nm. The presence of metal–oxygen bonds in the LaxNiyMn3–(x+y)O4 NPs was confirmed by FTIR analysis. The LaxNiyMn3–(x+y)O4 NPs could degrade crystal violet (CV) dye under visible light with a percentage degradation of 82%, which increased to 92% with the addition of 0.5 mL of 6% H2O2 solution. Furthermore, to increase the adsorption ability of the LaxNiyMn3–(x+y)O4 NPs, a composite LaxNiyMn3–(x+y)O4/SiO2 was synthesized. Under dark conditions, the adsorption percentage of the LaxNiyMn3–(x+y)O4 NPs was 58%, whereas that of LaxNiyMn3–(x+y)O4/SiO2 reached 73%. The adsorption process was further explored using adsorption isotherms and reaction kinetic models. The central composite rotatable design of response surface methodology was used to statistically maximize the adsorption of CV by optimizing factors such as time (40 min), pH (8.68), and composite dose (12 mg). The prominent diffraction peak in the XRD pattern and the large surface area (532 m2/g) determined via Brunauer–Emmett–Teller analysis of the composite confirmed its unique porous characteristics, illustrating its high capacity for adsorbing pollutants inside the porous network. Studies on the degradation efficiency and adsorption–photocatalysis synergy suggest the substantial potential of the synthesized composite for application in environmental remediation.