Preparation and Characterization of Functionalized Cellulose Nanomaterials (CNMs) for Pb(II) Ions Removal from Wastewater

Due to their remarkable properties, cellulose nanomaterials are emerging materials for wastewater (WW) treatment. In this study, both pristine cellulose nanomaterial (CNM) and sodium periodate modified cellulose nanomaterial (NaIO4-CNM) were prepared from the stem of the Erythrina brucei plant for the removal of Pb(II) ions from WW. As-prepared CNMs were characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), scanning electron microscope (SEM), and thermogravimetric analysis with differential thermogravimetry (TGA-DTG) analysis. The as-prepared and characterized CNMs were tested for the removal of Pb(II) ions from secondary run-off wastewater (SERWW). Langmuir and Freundlich adsorption isotherms were certainly fixed to a maximum Pb(II) ions uptake capability (Qmax) of 91.74 and 384.62 mg g−1 by CNM and NaIO4-CNM adsorbents, respectively. The pseudo-second-order (PSO) kinetics model was well fitted to the uptake process. Results revealed that the percentage removal (%R) of Pb(II) ions was decreased by the presence of nitrogen and organic matter, but not affected by the presence of phosphorous in SERWW. Due to its high efficiency, NaIO4-CNM was selected for the regeneration study. The regeneration study was conducted after desorption of Pb(II) ions from the adsorbent by the addition of HCl, and the regenerated sorbent was reused as an adsorbent for at least 13 successive cycles. The results indicated excellent recycling capabilities, and the adsorbent was used as adsorbing material for the removal of Pb(II) ions from SERWW after 13 successive cycles without significant efficient loss

Use of Different Natural Products to Control Growth of Titanium Oxide Nanoparticles in Green Solvent Emulsion, Characterization, and Their Photocatalytic Application

Water, one of the crucial and the pillar resources to every living thing, could be polluted day to day by different causes such as expansion in industrialization, rapid increment in population size, the threat of climate, and growth of urbanization. The existence of a number of organic dyes, detergents, and pesticides from industrial effluents could lead to severe diseases and even to the death of human beings. Currently, remediation of those hazardous organic contaminants using semiconductor metal oxide catalysts has received extensive attention in recent years. Among the numerous nanometal oxides, titanium oxide (TiO2) nanoparticles (NPs) have been well known as a significant photocatalytic material due to their suitable physiochemical behaviors such as stability, conductivity, high surface area to volume ratio, structure, and porosity nature at the nanoscale level. TiO2 semiconductor nanoparticles could be synthesized via several physiochemical approaches; among those, the biogenic technique is the most selective one which involves the synthesis of NPs using different templates. Biogenic synthesis of nanoparticles is an environmentally friendly protocol that involves the use of different parts and types of biogenic sources such as bacteria, fungi, yeast, virus, and green plants or the byproducts of their metabolism, which act as both reducing and stabilizing agents. TiO2 NPs obtained via the biogenic method provide a potential application for the degradation of organic dyes and other pollutants in wastewater. This method of synthesis of NPs has been given a great attention by researchers due to their nontoxicity, low cost, environmental friendliness, the usage of green solvents, and simplicity of the process. This review focuses on summarizing the synthesis of TiO2 NPs using various biogenic sources, characterization, and their photocatalytic applications for the degradation of different wastes and organic dyes from polluted water

A novel modified cellulose nanomaterials (CNMs) for remediation of chromium (VI) ions from wastewater

Wastewater (WW) remediation technologies were the most crucial issues all over the world at present time. Thus, the remediation of Cr (VI) ions from real WW was conducted using green biocompatible and biodegradable pristine (CNM) and succinic anhydride functionalized cellulose nanomaterial (S-CNM) adsorbents. Both CNM and S-CNM adsorbents were prepared by using sulfuric acid hydrolysis method and characterized for particle sizes, functional groups, and surface morphologies by using XRD, FT-IR, and SEM instruments, respectively. The physicochemical properties of the collected WW were investigated. Next, both the prepared adsorbents were applied for the remediation of Cr (VI) ions from WW. The remediation processes is spontaneous and have higher remediation efficiencies of Cr (VI) ions from WW. The Cr (VI) ions remediation mechanism was evaluated from both the Cr (VI) ions adsorption isotherms and kinetic concepts. Both Langmuir and Freundlich Cr (VI) ions adsorption isotherm models were certainly fixed to a maximum Cr (VI) ions uptake capability (q _max ) of 60.24 and 156.25 mg g ^−1 by CNM and S-CNM sorbents, respectively, and it follows pseudo-second-order (PSO) kinetics model through chemisorption processes. The Cr (VI) ions uptake capabilities were hindered by the presence of organic matter and any other competing pollutants in the WW. The S-CNM sorbent was selected for the regeneration study due to its higher efficiencies of remediation relative to CNM sorbent and the study was conducted through desorption of Cr (VI) ions by using HCl. Findings have shown that the sorbent was easily recyclable and applicable for the remediation of pollutants from real WW after consecutive 13th cycles

Green synthesis of p-Co3O4/n-ZnO composite catalyst with Eichhornia Crassipes plant extract mediated for methylene blue degradation under visible light irradiation

The water pollution due to industrial effluents causes a great health problem. Hence, it is important to treat wastewater before discharging to the environment. In this work, water hyacinth ( Eichhornia Crassipes ) plant extract mediated ZnO, CO _3 O _4 , and p-CO _3 O _4 /n-ZnO composite catalysts were synthesized by green co-precipitation routes. The resulting samples were characterized by x-ray diffractometer (XRD), scanning electron microscope (SEM), Fortier transform infrared (FT-IR), and with other instruments. The catalytic activities of ZnO, Co _3 O _4 , and Co _3 O _4 /ZnO were tested for MB dye degradation under visible light irradiation. The catalytic degradation of MB with p-CO _3 O _4 /n-ZnO composite catalyst was 95.5%; while 72% and 79% of MB dye was degraded by ZnO and Co _3 O _4 catalysts, respectively. The kinetic rate constants (k) in the degradation of MB dye with ZnO, Co _3 O _4 , and p-CO _3 O _4 /n-ZnO composite catalysts were also 0.014 min ^−1 , 0.018 min ^−1 , and 0.028 min ^−1 , respectively. The results showed that the presence of plant extract during the synthesis of the catalysts makes the catalyst more active and enhances the catalytic performances. Moreover, the formation of p-n junction in the p-CO _3 O _4 /n-ZnO catalyst also facilitates the photogenerated electron–hole separation and further enhances the catalytic efficiency. Hence, the formation of p-n junction is the key factor for enhancing the photodegradation of MB dye under visible light irradiation and the plant extract mediated catalyst synthesis also further improves its performance

Synthesis of Zinc Oxide Nanoparticles Using Leaf Extract of Lippia adoensis (Koseret) and Evaluation of Its Antibacterial Activity

The synthesis of metal oxide nanoparticles with the use of medicinal plant extract is a promising alternative to the conventional chemical method. This work aimed to synthesize zinc oxide nanoparticles using a green approach from indigenous “Koseret” Lippia adoensis leaf extract which is an endemic medicinal plant and cultivated in home gardens of different regions of Ethiopia. The biosynthesized zinc oxide nanoparticles were characterized using thermogravimetric analysis, X-ray diffraction, scanning electron microscopy-energy dispersive spectroscopy, transmission electron microscopy, ultraviolet-visible spectroscopy, and Fourier transform infrared spectroscopy. Furthermore, this study also evaluated the antibacterial activity of the synthesized ZnO nanoparticles against clinical and standard strains of Escherichia coli, Klebsiella pneumonia, Staphylococcus aureus, and Enterococcus faecalis by the disc diffusion method. According to the result of this study, ZnO nanoparticles synthesized using Lippia adoensis leaf extract showed promising result against both Gram-positive and Gram-negative bacterial strains with a maximum inhibition zone of 14 mm and 12 mm, respectively, using uncalcinated form of the synthesized ZnO nanoparticles

Microwave-Assisted Synthesis of CuO Nanoparticles Using Cordia africana Lam. Leaf Extract for 4-Nitrophenol Reduction

Copper-oxide-based nanomaterials play an important role as a low-cost alternative to nanoparticles of precious metals for the catalytic reduction of 4-nitrophenols. In this study, CuO nanoparticles were synthesized by a microwave-assisted method using Cordia africana Lam. leaf extract for reduction or stabilization processes. The synthesized CuO nanoparticles (NPs) were characterized using X-ray diffraction analysis (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and energy-dispersive spectroscopy (EDS). The analysis indicated that nanocrystals of the monoclinic CuO phase having a cluster of agglomerated morphology with a crystallite size of about 9 nm were synthesized. We also evaluated the catalytic performance of CuO NPs against 4-nitrophenol (4-NP) reduction. The catalyst has shown excellent performance completing the reaction within 12 min. Furthermore, the performance of CuO NPs synthesized at different pH values was investigated, and results indicated that the one synthesized at pH 7 reduced 4-NP effectively in shorter minutes compared to those obtained at higher pH values. The CuO NPs synthesized using Cordia africana Lam. leaf extract exhibited a better reducing capacity with an activity parameter constant of 75.8 min−1·g−1. Thus, CuO synthesized using Cordia africana Lam. holds a potential application for the catalytic conversion of nitroarene compounds into aminoarene

Synthesis of Titanium Oxide Nanoparticles Using Root Extract of Kniphofia foliosa as a Template, Characterization, and Its Application on Drug Resistance Bacteria

Biogenic methods of synthesis of nanoparticles (NPs) using plant extracts have been given a great attention due to its nontoxicity and environmental friendliness. In this study, TiO2 NPs were synthesized from titanium tetrabutoxide and extract of root of Kniphofia foliosa. NPs of TiO2 were biosynthesized at different volume compositions of titanium tetrabutoxide to the plant extract with a ratio of 1 : 2, 1 : 1, and 2 : 1, respectively. These green synthesized NPs of TiO2 were characterized by thermogravimetric analysis (TGA/DTA), X-ray diffraction (XRD), scanning electron microscope-energy dispersive X-ray spectroscopy (SEM-EDS), transmission electron microscopy (TEM), ultraviolet-visible spectroscopy (UV-Vis), and Fourier transform infrared (FTIR) spectroscopy. TGA/DTA analysis has confirmed that the synthesized NPs of TiO2 were stable above the temperature of 500°C. The sharp and intense peaks at 2θ values of 25.3, 38.0, 47.9, 53.2, 54.8862, 62.7, 70.2, and 75.0 have confirmed formation of crystalline NPs of TiO2 in the sample of 1 : 1 and 2 : 1 ratios, and less crystalline samples for TiO2 NPs prepared in a 1 : 2 ratio. Comparison between FT-IR absorption bands of the plant extract and that of calcined NPs of TiO2 confirmed the purity of synthesized nanomaterials, except unavoidable adsorption of moisture on the surface of TiO2 NPs in an open air. The antibacterial activity of biosynthesized TiO2 NPs and that of ethanolic root extract of Kniphofia foliosa was investigated via the disc diffusion method against human pathogen bacteria strains of Staphylococcus aureus, Escherichia coli, Klebsiella pneumonia, and Streptococcus pyogenes. Among the different ratios, TiO2 (1 : 1) NP shows better performance towards Gram-negative bacteria due to its smaller average crystalline size and uniform morphology observed in SEM image relative to the other two ratios of TiO2 NPs. Antibacterial activity of the ethanolic root extract of Kniphofia foliosa itself showed better performance towards Gram-negative bacteria than NPs of TiO2 that might be due to antibacterial activity of residue of ethanol left with the plant extract

Synthesis of Copper Oxide Nanoparticles Using Plant Leaf Extract of Catha edulis and Its Antibacterial Activity

Development of green technology is generating interest of researchers towards ecofriendly and low-cost methods for biosynthesis of nanoparticles (NPs). In this study, copper oxide (CuO) NPs were synthesized using a copper nitrate trihydrate precursor and Catha edulis leaves extract as a reducing and capping agent during the synthesis. The biosynthesized CuO NPs were characterized using an X-ray diffractometer (XRD), scanning electron microscopy-energy-dispersive X-ray spectroscopy (SEM-EDS), transmission electron microscope (TEM), Ultraviolet visible spectroscopy (UV-Vis), and Fourier transform infrared (FTIR) spectroscopy. XRD characterization confirmed that the biosynthesized CuO NPs possessed a good crystalline nature which perfectly matched the monoclinic structure of bulk CuO. Furthermore, the results obtained from SEM and TEM showed that the biosynthesized CuO NPs were spherical in shape. EDS characterization of the biosynthesized NPs also indicated that the reaction product was composed of highly pure CuO NPs. Moreover, the antimicrobial activities of different concentrations of CuO NPs synthesized using Catha edulis extract were also tested. Accordingly, the result showed that the highest zone of inhibitions measured were for CuO NPs synthesized using 1 : 2 ratios at 40 mg/ml solution concentration and observed to be 22 ± 0.01 mm, 24 ± 0.02 mm, 32 ± 0.02 mm, and 29 ± 0.03 mm for S. aureus, S. pyogenes, E. coli, and K. pneumonia, respectively

Microwave-Assisted Synthesis of rGO-ZnO/CuO Nanocomposites for Photocatalytic Degradation of Organic Pollutants

Nanomaterial-based catalytic conversion of hazardous organic pollutants into benign substances is one of the green methods employed for wastewater treatment. This study demonstrates the fabrication of (rGO-ZnO)/CuO nanocomposites (NCs) via a microwave (MW)-assisted method for (photo)catalytic application. The crystal structure, optical, morphological, and electrochemical characteristics were examined using X-ray diffraction (XRD), spectroscopic, microscopic, and electrochemical techniques. The analysis indicated that rod-like (rGO-ZnO)/CuO NCs having a nanoscale diameter with enhanced light absorption and well-matched band positions between rGO-ZnO and CuO were formed. Furthermore, the catalytic reduction of 4-nitrophenol (4-NP) and photocatalytic degradation of methylene blue (MB) tests showed remarkable results with rate constants of 0.468 min−1 for 4-NP reduction within 8 min and 0.02213 min−1 for MB degradation within 105 min. Thus, the artful decoration of ZnO nanorods (NRs) with CuO into the (rGO-ZnO)/CuO NCs interface is an effective strategy for fabricating highly efficient photocatalysts

Biotemplated Synthesis of Titanium Oxide Nanoparticles in the Presence of Root Extract of Kniphofia schemperi and Its Application for Dye Sensitized Solar Cells

Metal oxide nanoparticles prepared by biological route using green plant parts as a template are eco-friendly as well as yield good results than the conventional methods. This present study focusses on biosynthesis and characterization of TiO2 NPs using root extract of Kniphofia schemperi for dye-sensitized solar cells. TiO2 NPs were synthesized using 0.25 M titanium tetra butoxide in the presence of root extract of Kniphofia schemperi with the volume ratios. The analysis result revealed that the synthesized TiO2 NPs were thermally stable above 500°C and have spherical morphology, with the average crystalline size of 11.7, 8.3, and 8.6 nm, and band gap energy of 3.35 eV, 3.33 eV, and 3.36 eV, respectively, for the TiO2 NPs prepared at the volume ratios of 2 : 3, 1 : 1, and 3 : 2. Biosynthesized TiO2 NPs were used as photoanode in dye-sensitized solar cells (a device used for converting absorbed light into electricity). Solar cell devices were fabricated using roots of Kniphofia schemperi sensitizer in the presence of TiO2 NPs biosynthesized within (2 : 3, 1 : 1, and 3 : 2) volume ratio, which showed power conversion efficiency of 0.039%, 0.117%, and 1.3%. Incident photon to current conversion efficiency (IPCE) analysis using TiO2 (2 : 3, 1 : 1, and 3 : 2) photoelectrodes showed 6.64%, 2.66%, and 18%. Among the biosynthesized TiO2 different volume ratios, TiO2 (3 : 2) NPs showed relatively maximum solar cell efficiency and IPCE value due to its uniform spherical shape that enables to absorb large dye molecules on its surface, and this intern improves device efficiency