Preparation and characterization of rice husk activated carbon-supported zinc oxide nanocomposite (RHAC-ZnO-NC)

Sputtering thin films: Materials, applications, challenges and future directions

Sputtering is an effective technique for producing ultrathin films with diverse applications. The review begins by providing an in-depth overview of the background, introducing the early development of sputtering and its principles. Consequently, progress in advancements made in recent decades highlights the renaissance of sputtering as a powerful technology for creating thin films with varied compositions, structures, and properties. For the first time, we have discussed a thorough overview of several sputtered thin film materials based on metal and metal oxide, metal nitride, alloys, carbon, and ceramic-based thin film along with their properties and their applicability in various fields. We further delve into the applications of sputter-coated thin films, specifically emphasizing their relevance in environmental sustainability, energy and electronics, and biomedical fields. We critically examine the recent advancements in developing sputter-coated catalysts for eliminating water pollutants andhydrogen generation. Additionally, the review sheds light on advantages, shortcomings, and future directions for developing sputter-coated thin films utilized in biodegradable metals and alloys with enhanced corrosion resistance and biocompatibility. This review is a comprehensive integration of recent literature, covering diverse sputtering thin film applications. We delve deeply into various material types and emphasize critical analysis of recent advancements, particularly in environmental, energy, and biomedical fields. By offering insights into both advancements and limitations, the review provides a nuanced understanding essential for practical utilization.

Zinc oxide decorated plantain peel activated carbon for adsorption of cationic malachite green dye: Mechanistic, kinetics and thermodynamics modeling

Reports have shown that malachite green (MG) dye causes various hormonal disruptions and health hazards, hence, its removal from water has become a top priority. In this work, zinc oxide decorated plantain peels activated carbon (ZnO@PPAC) was developed via a hydrothermal approach. Physicochemical characterization of the ZnO@PPAC nanocomposite with a 205.2 m2/g surface area, porosity of 614.68 and dominance of acidic sites from Boehm study established the potency of ZnO@PPAC. Spectroscopic characterization of ZnO@PPAC vis-a-viz thermal gravimetric analyses (TGA), Fourier Transform Infrared Spectroscopy (FTIR), Powdered X-ray Diffraction (PXRD), Scanning Electron Microscopy and High Resolution - Transmission Electron Microscopy (HR-TEM) depict the thermal stability via phase transition, functional group, crystallinity with interspatial spacing, morphology and spherical and nano-rod-like shape of the ZnO@PPAC heterostructure with electron mapping respectively. Adsorption of malachite green dye onto ZnO@PPAC nanocomposite was influenced by different operational parameters. Equilibrium data across the three temperatures (303, 313, and 323 K) were most favorably described by Freundlich indicating the ZnO@PPAC heterogeneous nature. 77.517 mg/g monolayer capacity of ZnO@PPAC was superior to other adsorbents compared. Pore-diffusion predominated in the mechanism and kinetic data best fit the pseudo-second-order. Thermodynamics studies showed the feasible, endothermic, and spontaneous nature of the sequestration. The ZnO@PPAC was therefore shown to be a sustainable and efficient material for MG dye uptake and hereby endorsed for the treatment of industrial effluent.

Taguchi optimisation of the synthesis of vine-pruning-waste hydrochar as potential adsorbent for pesticides in water

This research aimed to synthesise an effective hydrochar adsorbent from vineyard pruning wastes to remove emerging contaminants as a potential valorisation product. The adsorption capacity of the hydrochar was optimised using the Taguchi method. Four synthesis variables were evaluated: hydrothermal reaction temperature, use of H3PO4 as a catalyst, number of acetone washes, and type of chemical cold activation. The simultaneous adsorption of five model pesticides (clothianidin (CTD), acetamiprid (ACE), 2,4-D, metalaxyl (MET), and atrazine (ATZ)) at an initial pH of 7 was studied. At optimum conditions, the hydrochar presented a total adsorption capacity of 22.7 μmol/g, representing a 2.7-fold improvement with respect to pristine hydrochar performance. High percentage removals were achieved for all pollutants (85 % CTD, 94 % ACE, 86 % MET, and 95 % ATZ) except for 2,4-D (4 %). This research provides a valuable reference for developing hydrochar adsorbents for pollution control and the valorisation of biomass wastes.

Adsorption of Nitrogen Dioxide on Nitrogen-Enriched Activated Carbons

The aim of this study was to obtain nitrogen-enriched activated carbons from orthocoking coal. The initial material was subjected to a demineralisation process. The demineralised precursor was pyrolysed at 500 °C and then activated with sodium hydroxide at 800 °C. Activated carbon adsorbents were subjected to the process of ammoxidation using a mixture of ammonia and air at two different temperature variants (300 and 350 °C). Nitrogen introduction was carried out on stages of demineralised precursor, pyrolysis product, and oxidising activator. The elemental composition, acid-base properties, and textural parameters of the obtained carbon adsorbents were determined. The activated carbons were investigated for their ability to remove nitrogen dioxide. The results demonstrated that the ammoxidation process incorporates new nitrogen-based functional groups into the activated carbon structure. Simultaneously, the ammoxidation process modified the acid-base characteristics of the surface and negatively affected the textural parameters of the resulting adsorbents. Furthermore, the study showed that all of the obtained carbon adsorbents exhibited a distinct microporous texture. Adsorption tests were carried out against NO2 and showed that the carbon adsorbents obtained were highly effective in removing this gaseous pollutant. The best sorption capacity towards NO2 was 23.5 mg/g under dry conditions and 75.0 mg/g under wet conditions.

Synthesis of X@DRHC (X=Co, Ni, Mn) catalyst from comprehensive utilization of waste rice husk and spent lithium-ion batteries for efficient peroxymonosulfate (PMS) activation

Highly efficient resource recycling and comprehensive utilization play a crucial role in achieving the goal of reducing resource wasting, environmental protection, and achieving goal of sustainable development. In this work, the two kinds waste resources of agricultural rice husk and metal ions (Co, Ni, and Mn) from spent lithium-ion batteries have been skillfully utilized to synthesize novel Fenton-like catalysts. Desiliconized rice husk carbon (DRHC) with rich pore structure and large specific surface area from rice husk has been prepared and used as scalable carrier, and dandelion-like nanoparticles cluster could be grown in situ on the surface of the carrier by using metal ions contained waste water. The designed catalysts (X@DRHC) as well as their preparation process were characterized in detail by SEM, TEM, BET, XRD and XPS, respectively. Meanwhile, their catalytic abilities were also studied by activating potassium peroxomonosulfate (PMS) to remove methylene blue (MB). The results indicate X@DRHC displays excellent degradation efficiency on MB with wide pH range and stable reusability, which is suitable for the degradation of various dyes. This work has realized the recycling and high-value utilization of waste resources from biomass and spent lithium-ion batteries, which not only creates an efficient way to dispose waste resources, but also shows high economic benefits in large-scale water treatment.

Rice Husk, Brewer's Spent Grain, and Vine Shoot Trimmings as Raw Materials for Sustainable Enzyme Production

Solid by-products with lignocellulosic structures are considered appropriate substrates for solid-state fermentation (SSF) to produce enzymes with diverse industrial applications. In this work, brewer's spent grain (BSG), rice husk (RH), and vine shoot trimmings (VSTs) were employed as substrates in SSF with Aspergillus niger CECT 2088 to produce cellulases, xylanases, and amylases. The addition of 2% (NH4)2SO4 and 1% K2HPO4 to by-products had a positive effect on enzyme production. Substrate particle size influenced enzyme activity and the overall highest activities were achieved at the largest particle size (10 mm) of BSG and RH and a size of 4 mm for VSTs. Optimal substrate composition was predicted using a simplex centroid mixture design. The highest activities were obtained using 100% BSG for β-glucosidase (363 U/g) and endo-1,4-β-glucanase (189 U/g), 87% BSG and 13% RH for xylanase (627 U/g), and 72% BSG and 28% RH for amylase (263 U/g). Besides the optimal values found, mixtures of BSG with RH or VSTs proved to be alternative substrates to BSG alone. These findings demonstrate that SSF bioprocessing of BSG individually or in mixtures with RH and VSTs is an efficient and sustainable strategy to produce enzymes of significant industrial interest within the circular economy guidelines.