Halan Prakash

Photocatalysis is promising for the degradation of antibiotic pollutants in water, which are known to cause the emergence of harmful antibiotic-resistant bacteria (ARB). Importantly, photocatalytic degradation of antibiotic pollutants in water with loss of antibacterial activity in an energy-efficient manner needs to be explored. Here, for the first time, we report degradation of tetracycline (TC), a known antibiotic pollutant in water, with removal of its antibiotic activity by cubic-barium stannate (BaSnO₃, BSO) perovskite photocatalytic nanoparticles under a blue LED light (367 nm) irradiation, (BSO/LED) system. XRD results revealed a single cubic phase of BSO with a crystallite size of 35 nm. FESEM and TEM images showed that BSO had cubic block-like morphology. BET analysis revealed the mesopores nature of BSO with a surface area of 1.1 m² g⁻¹. XPS confirmed the existence of Ba⁺² and Sn⁺⁴ ions. The bandgap energy of BSO was determined to be ∼3.2 eV. Importantly, photolysis of BSO under blue LED light caused complete degradation of TC in water, with a pseudo-first-order rate constant (k_obs) value determined as 0.0824 min⁻¹. Radical scavenging and ESR results revealed O₂ ^˙− and holes were profoundly generated in the BSO/LED system, causing degradation of TC along with antibiotic activity removal. Electrical energy per order (E_EO) was determined as 13.63 kWh per m³ per order, revealing that the BSO/LED system is energy-efficient. Further, BSO was reused four times, highlighting its stability. Degradation byproducts were predicted to be non-toxic by ecological structure activity relationship analysis. Thus, the study discloses an effective photocatalytic degradation of TC along with removal of its antibacterial activity that is needed to prevent hazardous ARB, by a stable non-lead-perovskite nano-photocatalyst under an energy-efficient LED source.

An easy recoverable TiO ₂ -immobilized PVDF bead photocatalyst with stable Ti–F binding for water treatment under UVA LED irradiation and efficient usage of TiO ₂ nanoparticles is presented.

We present the synthesis of Activated Carbon (AC) by pyrolysis of Banana (Musa Acuminate) Stem Waste (BSW), and the ability of obtained AC for adsorptive removal of Pb(II) ions from water. Importantly, pyrolysis was performed at 750°C for 2.0 h in the presence of high surface area producing chemical activators such as NaOH, LiOH, H₃PO₄, ZnCl₂, and KOH. BET-surface areas of AC produced with activators NaOH, LiOH, H₃PO₄, ZnCl₂, and KOH were determined to be 908, 1531, 1670, 2245, and 2485 m² g⁻¹, respectively. Pore volume ascending order was determined as 0.59 (NaOH) < 0.68 (LiOH) < 0.86 (H₃PO₄) < 0.97 (ZnCl₂) 3 g⁻¹. SEM and TEM images revealed the porous nature of the ACs. ACs produced with H₃PO₄, ZnCl₂, and KOH exhibit type I adsorption isotherms, indicating their microporous nature. ACs prepared with NaOH and LiOH exhibit type II adsorption isotherms, indicating their macroporous nature. X-ray diffraction, X-Ray photoelectron, and Raman spectroscopy analysis revealed the graphitic structure of ACs. Pb(II) ion adsorption onto ACs surface obeyed the Langmuir model. It was found that the Pb(II) adsorption capacities of the ACs produced with NaOH, LiOH, H₃PO₄, ZnCl₂, and KOH as the chemical activators were 220, 283, 326, 329, and 435 mg g⁻¹, respectively, at the optimised conditions (pH = 6.6, contact time = 100 min, [ACs] = 0.125 g L⁻¹, at 30°C). The interaction between surface functional groups of ACs and Pb(II) ions was confirmed by X-Ray photoelectron and FT-Infrared spectroscopy. The negative values of ΔG^o and ΔH^o reveal that the Pb(II) ion adsorption onto the ACs surface is spontaneous and exothermic. The Pb(II) ion adsorption capacity increased with an increase in BET-SA and pore volume of ACs, with AC obtained from BSW with KOH exhibiting the highest adsorption capacity of 435 mg g⁻¹. Thus, the study highlights BSW, agricultural biomass waste is a low-cost and abundantly available carbon precursor to synthesise potential AC adsorbent for water treatment.