Development of PSA@PS-TiO2 nanocomposite photocatalyst: structure, mechanism, and application using response surface designs and molecular modeling

Abstract

Using periwinkle shell ash (PSA) and polystyrene (PS), a new-fangled PSA@PS-TiO2 photocatalyst was fabricated. The morphological images of all the samples studied using a high-resolution transmission electron microscope (HR-TEM) showed a size distribution of 50–200 nm for all samples. The SEM-EDX showed that the membrane substrate of PS was well dispersed, confirming the presence of anatase/rutile phases of TiO2, and Ti and O2 were the major composites. Given the very rough surface morphology (atomic force microscopy (AFM)) due to PSA, the main crystal phases (XRD) of TiO2 (rutile and anatase), low bandgap (UVDRS), and beneficial functional groups (FTIR-ATR), the 2.5 wt.% of PSA@PS-TiO2 exhibited better photocatalytic efficiency for methyl orange degradation. The photocatalyst, pH, and initial concentration were investigated and the PSA@PS-TiO2 was reused for five cycles with the same efficiency. Regression modeling predicted 98% efficiency and computational modeling showed a nucleophilic initial attack initiated by a nitro group. Therefore, PSA@PS-TiO2 nanocomposite is an industrially promising photocatalyst for treating azo dyes, particularly, methyl orange from an aqueous solution. HIGHLIGHTS The new photocatalyst prevented TiO2 aggregation into larger microspheres due to the carbon.; TiO2 was distributed within the mesoporous (PSA) and microporous (PS) layers of the membrane substrates.; Increased wt.% correlated with higher irregularity and roughness owing to the presence of doped PSA and TiO2 nanoparticles.; The bandgap reduces from 3.1 to 2.5 eV when PSA content increased from 0.5 to 5.0 wt.%.;

Keywords

• doping
• modeling
• photodegradation
• semiconductor
• toxic dye
• water pollution