Silver supported-Ag@PMOS onto thumb structured porous organosilica materials with efficient hetero-junction active sites for photo-degradation of methyl orange dye

Abstract

Azo dyes are extensively used in textile industry but their discharge with industrial effluents pollutes water resources which harms flora and fauna in the environment. Nanomaterials and composites have competent photo-catalytic efficiencies to reduce organic pollutants and inactivate micro-organisms. However, these photocatalysts suffer from structural leaching and instability, which makes their applications limited. The aim of present study is to overcome these limitations and to degrade methyl orange (MO) azo dye by providing organic-inorganic hetero-junction active sites under UV-visible light irradiation. Tween-80 templates were used to prepare porous methyacryl organo silicates (PMOS) by co-condensation of sodium silicate and 3-methacryloxypropyl trimethoxysilane. The fabrication of porous methyacryl organo silicate materials (Ag@PMOS) was carried out by reducing the silver moieties on and in the surfaces of PMOS. The resulting Ag@PMOS scaffolds were studied by Fourier transform infrared spectroscopy, which showed conformational vibrations of organic and silver moieties in fingerprint region. UV/visible spectroscopy was used to monitor photocatalytic efficiencies while thermogravimetric analysis displayed heat resistance competency of synthesized materials. Transmission electron microscopy demonstrated spherical particle shape of PMOS and well-ordered hexagonal patterns in Ag@PMOS, which were also enlightened by X-ray powder diffraction method. While, photoluminescence (PL) study examined the excessive formation of hydroxyl free radicals by Ag@PMOS during photocatalysis of MO. The synthesized material exhibited well-ordered crystalline networks of Ag@PMOS with good surface area, which made it effective for degradation of MO. The results showed 26% and 56% absorption reduction under visible and UV-conditions, respectively. Moreover, the reduction efficiency was increased remarkably after using hydrogen peroxide and found to be 53% and 85% under visible and UV-irradiation, respectively. The promising recycled results showed 24%, 21%, 17% (without using H₂O₂) and 54%, 51%, 48% (using H₂O₂) absorption decline under visible light irradiation. Moreover, 53%, 50%, 49% (without using H₂O₂) and 83%, 80%, 78% (using H₂O₂) absorption reductions were examined under UV-light irradiation without and with H₂O₂. Which pointed toward high reduction capabilities and better stability of Ag@PMOS. The synthesis of highly porous PMOS, efficient photo-degradation of MO under UV-light by fabricated Ag@PMOS and reproducibility of the degradation results made the present work more innovative for degradation of MO for water decontamination.

Keywords:

• Porous organo silicates
• hetero-junction
• active sites
• photo-degradation
• methyl orange

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

The authors extend their appreciation to the Deanship of Scientific Research at King Khalid University for funding this work through the research groups program [grant number R.G.P.2/157/42]. Also, the authors are highly thankful to Islamia University of Bahawalpur (IUB) and Higher Education Commission (HEC) of Pakistan for financial support.