A Facile Synthesis of Cellulose Acetate Functionalized Zinc Oxide Nanocomposite for Electrochemical Sensing of Cadmium ions

Development of environmentally friendly catalyst Ag-ZnO@cellulose acetate derived from discarded cigarette butts for reduction of organic dyes and its antibacterial applications

The release of harmful organic dyes from different industries besides its degradation products is a major contributor to environmental contamination. The catalytic reduction of these organic pollutants using nanocomposites based on polymeric material presents potential advantages for the environment. In this study, novel nanocomposite based on cellulose acetate (CA)-derived from discharged cigarette butts and zinc oxide nanoparticles (ZnO NPs) was prepared utilizing a very simple and low-cost solution blending method and used as support for silver nanoparticles (Ag NPs). A simple reduction method was used to anchor different percentages of Ag NPs on the ZnO@CA nanocomposite surface via utilizing sodium borohydride as a reducing agent. The Ag-ZnO@CA nanocomposite was characterized using X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and transmission electron microscopy. The TEM analysis showed spherical Ag NPs, with an average diameter of ∼17.6 nm, were uniformly anchored on the ZnO@CA nanocomposite surface. The prepared nanocomposites were evaluated as catalysts for the reduction of organic dyes in water. It was found that 10 % Ag-ZnO@CA nanocomposite showed a remarkable reduction of Rhodamine B (RhB), Rhodamine 6G (Rh6G), Methylene Blue (MB), and Sunset Yellow (SY) dyes in short time. In the presence of this nanocomposite, the rate constant, kapp values for RhB, Rh6G, MB, and SY were 0.3498 min-1, 1.51 min-1, 0.2292 min-1, and 0.733 min-1, respectively. This nanocomposite was recovered and reused in five successive cycles, with a negligible loss of its activity. Furthermore, the nanocomposites demonstrated moderate antibacterial activity toward Staphylococcus aureus and Escherichia coli. Thus, this study directed attention on recycling of waste material to a valuable nanocomposite and its applications in environmental protection.

Encapsulation of heavy metal ions via adsorption using cellulose/ZnO composite: First principles approach

The primary goal of the current research is to describe an effective and eco-friendly adsorbent for the removal of aquatic micropollutants. The design of the cellulose-modified zinc oxide (ZnO) nanocomposite was successfully carried out by density functional calculations. The proposed structures of the constituent and composite materials were confirmed using formation energy (Ef), frontier orbitals, band gaps (Egap), density of state (DOS) plots, natural bond orbitals (NBO), and UV-Vis spectral analysis. The cellulose/(ZnO)12 composite was further used for the adsorption of different heavy metal ions such as Hg(II), Pb(II), Cd(II), Ni(II), and As(III) through calculation of electronic and optical properties. The values of the adsorption energy (Eads) show that the As(III) interacted better with the composite in both phases, i.e., gas (-806.98 kcal/mol) and aqueous (-491.66 kcal/mol). The analysis of frontier molecular orbital data exhibited a decrease in the Egap of composite@metal ion complexes. The high negative value of the solvation energies (ΔEsol) indicates the suitability of composite@metal ions in an aqueous environment. The nature of interactions between metal ions and the composite unit is analyzed by noncovalent interactions (NCI) and the quantum theory of atoms in molecules (QTAIM). The theoretical results of the present study show the feasibility of the cellulose/(ZnO)12 composite for the removal of heavy metal ions and provide useful information to experimentalists to treat contaminated water.

A disposable modified screen-printed electrode using egg white/ZnO rice structured composite as practical tool electrochemical sensor for formaldehyde detection and its comparative electrochemical study with Chitosan/ZnO nanocomposite

In this study, Chitosan/ZnO nanocomposite (Ch/ZnO) and egg white/ZnO rice structured composite was synthesized by simple wet chemical technique and characterised by various techniques. A comparative electrochemical analysis were carried out and determined that egg white/ZnO rice structured composite modified screen printed electrode (SPCE) showed good electrochemical behaviour. The electrochemical activity of egg white/ZnO rice structured composite SPCE was investigated for the oxidation-reduction of formaldehyde in alkaline media using cyclic voltammetry (CV).Their unique electrocatalytic activity for the formaldehyde found to exhibit 254 mV cathodic current response towards low negative potentials. Based on these results, a novel screen printed sensor (Egg white albumin/ZnO rice structured composite) for the determination of formaldehyde was analysed using differential pulse voltammetry (DPV). The sensor response was linear from 0.001 mM to 0.005 mM with limit of detection (LOD) 6.2 nM and their sensitivity was found to be 770.68 mM/μA. The developed electrochemical formaldehyde sensor was successfully applied as working electrode in cyclic voltammetric determination of formaldehyde in urine samples. The sensor is selective, inexpensive, stable over several days and disposable as well as simple to manufacture and operate. The system described here can be easily be adapted to other substrates and used as practical tool for formaldehyde analysis.

Facile hydrothermal bio-synthesis of cellulose acetate templated CuS nanorods like fibres: antibacterial, cytotoxicity effects and DNA cleavage properties against A549 lung cancer cells

In this research, the hydrothermal method was used for synthesising cellulose acetate (CA) templated nanorods like CuS fibres using vegetable extract (Brassica oleracea var. italica). These extracts act as a reducing agent in the presence of CA. Surprisingly, when the same reaction was carried out in the absence of CA and broccoli extract, structural morphology disappeared and was found as agglomerated. In the presence of cellulose templated extract mediated CuS has revealed as nanorods like fibres and was confirmed by field emission scanning electron microscope analysis. Their crystallinity property of CuS nanoparticles (NPs) and cellulose templated biosynthesised CuS NPs was analysed and compared using X-ray diffraction technique. The biological activities of the obtained product were examined for antibacterial assessment against two bacterial strains that include two-gram negative strains (E.Coli and S. aureus). The nanostructured product found to exhibit excellent antibacterial agent against all the strains. Biosynthesised nanostructure showed its efficacy against A549 lung cancer cells which might attribute to a larger surface to volume ratio of nanorods like fibres. The authors observation suggest that CuS nanorods like fibres can significantly reduce the cell growth with IC₅₀ value of 31.2 μg/ml.

Production, characterization and effectiveness of cellulose acetate functionalized ZnO nanocomposite adsorbent for the removal of Se (VI) ions from aqueous media

In this study, ZnO functionalized cellulose acetate nanocomposite (ZnO/CA NC) was synthesized using a simple chemical approach found to have a high surface area of 657.34 m²/g and utilized as adsorbents for the removal of Se (VI) from aqueous solutions. Investigations on X-ray diffraction (XRD) revealed that ZnO nanocomposite has a smaller crystallite size compared to ZnO nanoparticles which facilitated for reduced agglomeration confirmed by scanning electron microscopy (SEM). The ensuing properties of ZnO/CA NC displayed high maximum adsorption capacity of 160.5 mg/g for Se (VI) ions. Inner-sphere surface complexes on ZnO/CA NC under prevailing conditions for Se (VI) were discussed using FTIR spectroscopical results. In order to evaluate the removal efficiency, the effects of adsorbent dosage, pH, and temperature were thoroughly investigated. The amount of Se (VI) ions adsorbed on ZnO/CA NC was also determined by zeta potential. The fractional removal of pollutants (Se (VI)) was done using mass transfer model. In addition, prominent adsorption capacity was also tested utilizing concurrent anions (SO₄^2-, Cl^-, and F^-) with reference to Se (VI) and cost prudent regenerability of adsorbent by NaOH solution was ascertained with anti-interference and recovery steps. ZnO/CA NC was obtained by simple chemical methodology and high surface adsorption capacities supply an encouraging technique for Se (VI) removal in water treatment applications.