Influences of calcination temperature on titanium dioxide nanoparticles synthesized using Averrhoa carambola leaf extract: in vitro antimicrobial activity and UV-light catalyzed degradation of textile wastewater

The aim of the work is the development of highly active TiO2 NPs by a novel green synthesis approach using Averrhoa carambola leaf extract with an effect on variation in calcination temperature which overcomes the problem of water pollution. The prepared TiO2 NPs are characterized by XRD, FTIR, SEM, EDAX, HRTEM, and UV-Vis. The XRD pattern reveals that the phase composition of prepared samples was found to be varied from 250 to 800 degrees C. At 250 and 350 degrees C, pure anatase phase was attained, whereas the anatase-rutile (mixed) phase was attained at 500 and 700 degrees C. The pure rutile phase was obtained at 800 degrees C. The micro-strain, dislocation density, and volume of the material were found to decline with increasing calcination temperature while the crystalline size increased significantly. Due to tiny crystalline size and pure anatase phase, degradation demonstrated outstanding performance against organic pollutants such as Malachite green (91 %) and Rhodamine B (92 %) which was attained in a period of 150 min under UV light irradiation. Also, the degradation of textile dyeing wastewater by TiO2 NPs with an efficiency of 89 % was procured when exposed to UV irradiation for 210 min. Green synthesized TiO2 NPs were carried out against the antimicrobial activity of Pseudomonas aeruginosa, Bacillus subtilis, and Candida parapsilosis. Among these pathogens, gram-negative Pseudomonas aeruginosa exhibited the highest zone of inhibition of 21 mm. The pure anatase phase attained at a calcination temperature of 250 degrees C leads to high photocatalytic degradation and antimicrobial activity. So, it can be possibly utilized for bio-medical and wastewater treatment.