Visible-light-driven photodegradation of organic pollutants by simply exfoliated kaolinite nanolayers with enhanced activity and recyclability.

The need for abundant photocatalyst in wastewater treatment is currently a must. A simple intercalation process was utilized to exfoliate Kaolinite clay mineral structure Al2Si2O5(OH)4 into two-dimensional nanostructured separated layers operated in visible light range. The intercalating agents were hydrazine hydrate and urea. Detailed characterization confirmed the nanolayered structures of kaolinite hexagonal nanosheets (NK). In addition, Bandgap energy was reduced based on intercalating agents from 3.45 to 2.48 eV as revealed by light absorption spectra. The quenching of PL spectra for the nK has also been ascribed to the suppression of charge carrier recombination. The exfoliated nK was utilized to photodegrade Rhodamine B dye (RhB) and P-nitrophenol (PNP) as industrial pollutants in wastewater. The results showed 92.3% and 99.7% photodegradation of RhB and PNP within 180 min of visible-light irradiation utilizing the exfoliated NK by urea. We denote the boosted photocatalytic performance of this NK to the uncovered, low bandgap metal oxide inclusions on the exterior of NK besides the nitrogen doping due to exfoliation with urea. This simple exfoliation has modified abundant and stable clay nanolayers that are a promising alternative for the eminent nanostructured oxide photocatalysts to overcome the organic pollutants in wastewater at a high scale.

From waste to value-added products: Evaluation of activated carbon generated from leather waste for supercapacitor applications.

Leather tanning operations create a large amount of solid and liquid waste from tanning, wherein Cr(III) compounds are used to produce wet blue leather. In this study, activated carbon (AC) generated from leather waste (LW) was evaluated for supercapacitor (SC) applications. AC was produced through carbonization at a temperature range of 700°C-900 °C, followed by chemical activation. The morphological characteristics of the AC samples revealed a certain degree of porosity and a maximum surface area of 381 m2 g-1. X-ray diffraction and EDX examination showed the existence of graphitic planes in the LW-derived AC. Raman, FT-IR, and XPS confirmed the defect nature and surface functional groups of the AC samples. A three-electrode approach was employed to assess the electrochemical characteristics of the AC samples. The supreme capacitance of a sample (LW700) at 1 A/g was 550 F g-1 (237 C g-1) in a 6 M KOH electrolyte. All the electrochemical results (CV, GCD, and Nyquist curves) demonstrated that the LW carbon possessed a high specific capacitance and electrochemical cycle constancy, and hence is appropriate for SC fabrication. These desirable capacitive performances enable solid leather waste-derived carbons as a source of new materials for low-cost energy storage supercapacitors. This work put forwards a new concept of 'waste to value-added products' that can be a helping hand for leather industries and its solid waste management disposal problems.