Visible-Light-Active Zn–Fe Layered Double Hydroxide (LDH) for the Photocatalytic Conversion of Rice Husk Extract to Value-Added Products

Abstract

One of the major causes of excess CO2 in the atmosphere is the direct burning of biomass waste, which can be obviated by the photocatalytic biomass conversion to useful/valuable chemicals/fuels, a sustainable and renewable approach. The present research work is focused on the development of a novel Zn–Fe LDH by a simple co-precipitation method and its utilization for the photocatalytic conversion of a rice husk extract (extracted from rice husk by means of pyrolysis) to value-added products. The synthesized, pure Zn–Fe LDH was characterized by various analytical techniques such as XRD, SEM, FTIR, and UV–Visible DRS spectroscopy. The rice husk extract was converted in a photocatalytic reactor under irradiation with 75 W white light, and the valued-added chemicals were analyzed by gas chromatography–mass spectrometry (GC–MS). It was found that the compounds in the rice husk extract before the photocatalytic reaction were mainly carboxylic acids, phenols, alcohols, alkanes (in a small amount), aldehydes, ketones, and amines. After the photocatalytic reaction, all the carboxylic acids and phenols were completely converted into alkanes by complex reactions. Hence, photocatalytic biomass conversion of a rice husk extract was successfully carried out in the present experimental work, opening new avenues for the development of related research domains, with a great potential for obtaining an alternate fuel and overcoming environmental pollution.

Efficient Dye Degradation and Antimicrobial Behavior with Molecular Docking Performance of Silver and Polyvinylpyrrolidone-Doped Zn-Fe Layered Double Hydroxide

“…Crystal structure, phase identification, and crystallite size were analyzed using X-ray diffraction (XRD) patterns (Figure a). The diffraction peaks observed around 31.79, 34.42, 36.22, 47.87, 56.63, 62.90, and 67.87° at 2θ° correspond to characteristic basal reflections (003), (006), (009), (012), (015), (118), and (110), respectively, confirmed the successful formation of Zn–Fe LDH . Adding PVP reduced peak intensity, which revealed a decrease in crystallinity due to the amorphous nature of PVP .…”

“…The following expression, a linear slope used to determine the optical band gaps: (α h υ) 1/ n = A ( h υ – E g ), where α, h υ, A , and E g attributed coefficient of absorption, light energy, the proportionality constant, and forbidden gap energy. The band gap of pure sample was around 2.84 eV . The calculated band gap energy of pure, PVP/LDH, and (1, 3, and 5 wt %) Ag-doped samples were 2.81, 2.70, 2.57, 2.47, and 2.38 eV, respectively, showing the surface plasmon resonance effect of Ag as the dopant (Figure b) .…”

“…The band gap of pure sample was around 2.84 eV. 34 The calculated band gap energy of pure, PVP/LDH, and (1, 3, and 5 wt %) Ag-doped samples were 2.81, 2.70, 2.57, 2.47, and 2.38 eV, respectively, showing the surface plasmon resonance effect of Ag as the dopant (Figure 4b). 44 Upon increasing the doping concentration of Ag, peaks shifted toward higher wavelengths, showing a homogeneous strain, which boosts the active site on the surface of prepared nanocomposites that are considered helpful in CA and bactericidal activity.…”

“…UV–vis spectra were used to examine the electronic transitions of doped and undoped samples (Figure a). Zn–Fe represented a low absorption edge of nearly 490 nm, describing the weak efficiency of e – /h + pair generation . Doped samples showed strong absorption in the visible region, improving the e – /h + pair recombination .…”

Peroxydisulfate-assisted sonocatalytic degradation of metribuzin by La-doped ZnFe layered double hydroxide

“…The strong peaks observed at approximately 3455.5 cm −1 are attributed to the stretching vibration of hydrogen-bonded hydroxyl groups from both the hydroxyl group in the layers and the interlayer water [18] . The peaks observed at 1607.5 cm −1 are explained by the bending vibration of the interlayer water molecules ( v H — O — H ) [31] . 1350–1500 cm −1 due to the stretching vibration of carbonate anions in the interlayer [22] .…”