Biosynthesis, Characterization and Biological Applications of Silver Nanoparticles using Celosia trigyna and Solanum nigrum Extracts: Neglected Vegetables in Nigeria

Plant-mediated synthesis is gaining acceptance in many fields i.e. biology and pharmaceutical fields. This aim of this study is synthesizing Ag nanoparticles using air-dried leaves of two (2) neglected vegetables i.e.  Celosia trigyna and Solanum nigrum.  Ultraviolet–visible spectroscopy, fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM) were used to characterize the formation of silver nanoparticles (AgNPs). The anti-inflammatory properties of these AgNPs were evaluated using Cell Stabilization Membrane (CSM) and lipoxidase assays, their antioxidant activity were established on DPPH and ABTS+ assays. The positive control employed are indomethacin and ascorbic acid for these activities. Nanoparticles synthesized were labelled for Celosia trigyna (CT-AgNPs) and Solanum nigrum (SN-AgNPs) were noticed through visual color change. The UV–Vis spectra of the synthesized nanoparticles displayed absorption bands at around 360-440 nm, which is a characteristic band for Ag and FTIR displayed possible functional groups responsible for Ag nanoparticles synthesized by these plants.  The SEM image of the AgNPs formed displayed were spherical in morphology. CT-AgNPs exhibited the most significant inhibitory activity against HRBC (IC50: 32.2 µg/ml) while SN-AgNPs displayed the most significant inhibitory activity against lipoxygenases (IC50: 32.8 µg/ml) when compared to the positive control used indomethacin (IC50: 28.1 µg/ml). SN-AgNPs exhibited the most significant antioxidant effect against ABTS (IC50: 11.4 µg/ml) while CT-AgNPs displayed the most significant antioxidant activity against DPPH (IC50: 4.6 µg/ml) when compared to the positive control used ascorbic acid (IC50: 4.7 µg/ml). This work showed that the synthesized AgNPs from non-cultivated vegetable can find relevance and application in health, drugs, food and environmental science

Preparation and Characterization of Biochar and Activated Carbon Derived from Cashew Bagasse Waste

Biochar and Activated carbon derived from cashew bagasse waste are veritable materials produced from agro-waste. They are currently under-utilized owing to paucity of information in their recycling methods which reduces agricultural waste from the environment. This study investigates the use of under-utilized cashew bagasse waste in the production of biochar and activated carbon using pyrolysis and chemical activation methods, respectively. Cashew bagasse waste was pyrolysed at 4000C for 20mins at a heating rate of 100C per mins. The biochar produced was allowed to cool at room temperature for 30 mins. It was further reduced to smaller size particles using euro premium grinder and later sieved with 10 mesh sieve size prior to its application. The biochar was chemically activated using 0.3M Orthophosphoric acid (H3PO4) as activating agent at an impregnation ratio of 1:2.36(w/w). It was heated at 1000C to form a paste and later placed in muffle furnace at 5000C for 30 mins. This was allowed to cool and washed with distilled water until a neutral pH was obtained and later oven dried at 1050C for 24 hours to a constant weight to produce activated carbon. The produced activated carbon was kept in air tight containers prior to analysis. Characterization of pH, bulk density, moisture content, dry matter, volatile matter, and fixed carbon were determined for biochar and activated carbon. Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM) analysis was performed to determine the functional groups and surface morphology of biochar and activated carbon, respectively. The Data obtained were analyzed using descriptive statistics and ANOVA at P value < 0.05. The results showed that significant differences (p<0.05) were observed in the characterized parameters determined. The biochar and activated carbon has pH: (7.68±0.06 and 6.13±0.03); Bulk density :( 0.18±0.01 and 0.20±0.01) %; Moisture content: (6.67±0.33 and 16.00±0.58)%; Dry matter (93.33±0.33 and 84.00±0.58) %; Volatile matter (68.67±3.18 and 29.67±5.21) %; Fixed carbon (30.24±3.20 and 69.32±5.16) %, respectively. FTIR Analysis showed that biochar and activated carbon were more polar and also contained specific bonds. SEM analysis also indicated that biochar and activated carbon have porous structures. This study, therefore, revealed that chemically activated carbon had better characteristics than biochar produced through pyrolysis method

Formaldehyde free particleboards from wood chip wastes using glutaraldehyde modified cassava starch as binder

The study determined some physical and mechanical properties of particleboards produced from wood chip wastes and modified cassava starch (MCS). The native cassava starch was modified with 25% glutardialdehyde solution. Density, water absorption (WA), thickness swelling (TS), modulus of elasticity (MOE) and modulus of rupture (MOR) were evaluated based on Japanese Industrial Standard (JIS). Scanning electron microscope (SEM) Fourier-transform infrared spectroscopy (FTIR) were utilised to conduct the microstructural and elemental analyses of the particleboards. Density ranged from 0.21 to 0.54 g/cm3 , WA ranged from 32.7 to 168.9% after 2 and 24 h immersion while TS ranged from 1.8 to 67.9% after 2 and 24 h immersion. Peak values at 3232.0 N/mm2 and 35.7 N/mm2 for MOE and MOR were recorded for the MCS bonded boards. SEM showed well-dispersed MCS granules on the surface of the particleboards while FTIR indicated the occurrence of aldehyde and ester forms attributed to MCS binder. The modified cassava starch bonded boards showed good prospects for utilization in non-load applications having displayed a better performance than the unmodified particleboards

Biosynthetic modulation of carbon-doped ZnO for rapid photocatalytic endocrine disruptive remediation and hydrogen evolution

Pharmaceuticals and industry effluents such as dyes, and organic contaminants in wastewater are being identified among the top endocrine disruptive compounds with inherent recalcitrant and hazardous effects. Herein, microwave-induced coconut shell-activated carbon-doped-zinc-oxide (CSAC-ZnO) nanocomposites at various calcined temperatures were synthesized by hydrothermal techniques, characterized and applied towards photocatalytic degradation of endocrine disruptive compounds (EDC) and green energy generation via photocatalytic hydrogen production. The surface area, structural crystallinity, optical properties, thermal stability, functional group and morphological properties were accessed via Powdered X-ray diffraction, UV-Diffuse Reflectance Spectroscopy, Fourier Transform Infrared, Thermal Gravimetric Analysis, Brunauer-Emmett-Teller, X-ray Photoelectron Spectroscopy, Scanning Electron Microscopy, and Transmission Electron Microscopy. An extremely high surface area of 320.65 m2g-1 was observed from the as-prepared carbon decorated (CSAC-ZnO) and excellent light absorption was shown by all the photocatalysts. The exceptional photo-degradation efficiencies of CSAC-ZnO on methylene blue (MB) cationic dye as well as ibuprofen (IBP) pharmaceutical are reported. Very rapid 91% MB and 94% IBP pharmaceutical degradation efficiency obtained within 60 min and 30 min, respectively were observed. The kinetics of the photocatalytic activities at different pH followed pseudo-first-order kinetics. The Liquid Chromatography-Mass Spectrometry analysis on MB and IBP before and after photodegradation confirmed the formation of intermediate products. The modulated CSAC-ZnO@600 exhibits hydrogen production of 18947μmolg−1h−1. The photocatalysts showed current densities ranging from 0.03 to 0.05 mA/cm2. The Fast charge transfer is supported by electrochemical impedance spectroscopy and −0.3 and −0.49 V versus Ag/AgCl flat band potentials. The relation between the electronic and catalytic properties is revealed from the calculation of density functional theory (DFT). The study revealed the impact of calcination on the properties of the biomass carbon-doped-photocatalysts, excellent photocatalytic degradation efficiency and efficient hydrogen production from water-splitting giving relevance to biomass carbon-doped CSAC-ZnO in environmental remediation and green energy production

Surface Modified Low Cost Adsorbent in Malachite Green Scavenging, Malachite Green/Rhodamine B and Malachite Green/Rhodamine B/Cu2+ Composite Treatment

Modified Irvingia gabonensis nut waste (MIg) was used for malachite green (MG) removal from aqueous solution. Adsorption operational parameters such as pH, adsorbent load, concentration with contact time were investigated to establish the behavior of MIg for subsequent applications in a complex media. The potency of MIg in the effective treatment of binary and ternary mixture of MG/rhodamine B (RhB) dyes and MG/RhB/Cu2+ solution was also studied. Optimum MG adsorption was obtained at pH of 6.0. MG-MIg kinetics adsorption data was best described by the Pseudo second order kinetic model. MG adsorption onto MIg was predominantly onto a uniform site and the maximum monolayer adsorption capacity was obtained to be 250mg/g. MG and RhB synergistically aided the removal of each other both in binary and ternary solutions hence 99.99% removal was observed for the two dyes after treatment with MIg. Cu2+ showed no change in concentration after treatment with MIg

Modelling of moisture diffusivity during solar drying of locust beans with thermal storage material under forced and natural convection mode

This study investigated the modelling of moisture diffusivity of processed locust beans under forced and natural convection mode using solar drying with thermal storage materials (gravel). The experimental data obtained were fitted into eleven existing thin layer models and the best model choice was based on a comparison of statistical parameters including determination coefficient (R2), reduced chi-square (ᵪ2), root mean square error (RMSE), square error sum (SSE) and normalised root mean square error (NRMSE) between the experimental and predicted data. The results showed that the Lewis model gave the best description of solar drying of locust beans under forced and natural convection mode. Thus, this model may be adjudged to represent the drying characteristics of locust beans in a thin layer within the experimental range of study. The obtained moisture diffusivity values were 2.73496 and 1.82331 10-11 m2/s for the solar drying of locust beans under forced and natural convection mode respectively. The predicted Arrhenius constant and activation energy values were respectively 2.54 10-11 m2/s and 21.65 kJ/mol