Central composite design and mechanism of antibiotic ciprofloxacin photodegradation under visible light by green hydrothermal synthesized cobalt-doped zinc oxide nanoparticles

In this research, different Co2+ doped ZnO nanoparticles (NPs) were hydrothermally synthesized by an environmentally friendly, sustainable technique using the extract of P. capillacea for the first time. Co-ZnO was characterized and confirmed by FTIR, XPS, XRD, BET, EDX, SEM, TEM, DRS UV-Vis spectroscopy, and TGA analyses. Dislocation density, micro strains, lattice parameters and volume of the unit cell were measured using XRD results. XRD suggests that the average size of these NPs was between 44.49 and 65.69 nm with a hexagonal wurtzite structure. Tauc plot displayed that the optical energy bandgap of ZnO NPs (3.18) slowly declines with Co doping (2.96 eV). Near complete removal of the ciprofloxacin (CIPF) antibiotic was attained using Green 5% of Hy-Co-ZnO in the existence of visible LED light which exhibited maximum degradation efficiency (99%) within 120 min for 30 ppm CIPF initial concentration. The photodegradation mechanism of CIPF using Green Hy-Co-ZnO NPs followed the Pseudo-first-order kinetics. The Green Hy-Co-ZnO NPs improved photocatalytic performance toward CIPF for 3 cycles. The experiments were designed using the RSM (CCD) method for selected parameters such as catalyst dosage, antibiotic dosage, shaking speed, and pH. The maximal CIPF degradation efficiency (96.4%) was achieved under optimum conditions of 39.45 ppm CIPF dosage, 60.56 mg catalyst dosage, 177.33 rpm shaking speed and pH 7.57.

Hydrogen bond-mediated self-assembly of Tin (II) oxide wrapped with Chitosan/[BzPy]Cl network: An effective bionanocomposite for textile wastewater remediation

A novel and efficient bionanocomposite was synthesized by incorporating SnO into chitosan (Ch) and a room-temperature ionic liquid (RTIL). The bionanocomposite was synthesized in benzoyl pyridinium chloride [BzPy]Cl to maintain the unique properties of SnO, chitosan, and the ionic liquid. Adsorption and photodegradation processes were applied to evaluate the bionanocomposite for removing azo and anthraquinone dyes and textile wastewater. SnO/[BzPy]Cl and SnO/[BzPy]Cl/Ch samples were prepared and characterized using various techniques, including FT-IR, SEM, XRD, EDAX, XPS, DSC, TGA, nitrogen adsorption/desorption isotherm, and DRS analysis. SEM analysis revealed a hierarchical roughened rose flower-like morphology for the biocomposite. The band gap energies of SnO/[BzPy]Cl and SnO/[BzPy]Cl/chitosan were found to be 3.9 and 3.3 eV, respectively, indicating a reduction in the band gap energy with the introduction of [BzPy]Cl and chitosan. SnO/[BzPy]Cl/Ch showed high removal rates (92-95 %) for Fast Red, Blue 15, Red 120, Blue 94, Yellow 160, and Acid Orange 7 dyes. The adsorption kinetics followed a pseudo-second-order model. In addition, the effect of different photodegradation parameters such as solution pH, dye concentrations, contact time, and amount of photocatalyst, was studied. Given the optimal results obtained in removing azo and anthraquinone dyes, the SnO/[BzPy]Cl/Ch nanocomposite was used as an efficient nanocomposite for removing dyes from textile wastewater. The highest removal efficiency was found to be 95.8 %, obtained under ultraviolet and visible light. Furthermore, BOD and COD reduction analysis showed significant reductions, indicating the excellent performance of the photocatalyst.

Biopolymeric Nanocomposites for Wastewater Remediation: An Overview on Recent Progress and Challenges

Essential for human development, water is increasingly polluted by diverse anthropogenic activities, containing contaminants like organic dyes, acids, antibiotics, inorganic salts, and heavy metals. Conventional methods fall short, prompting the exploration of advanced, cost-effective remediation. Recent research focuses on sustainable adsorption, with nano-modifications enhancing adsorbent efficacy against persistent waterborne pollutants. This review delves into recent advancements (2020-2023) in sustainable biopolymeric nanocomposites, spotlighting the applications of biopolymers like chitosan in wastewater remediation, particularly as adsorbents and filtration membranes along with their mechanism. The advantages and drawbacks of various biopolymers have also been discussed along with their modification in synthesizing biopolymeric nanocomposites by combining the benefits of biodegradable polymers and nanomaterials for enhanced physiochemical and mechanical properties for their application in wastewater treatment. The important functions of biopolymeric nanocomposites by adsorbing, removing, and selectively targeting contaminants, contributing to the purification and sustainable management of water resources, have also been elaborated on. Furthermore, it outlines the reusability and current challenges for the further exploration of biopolymers in this burgeoning field for environmental applications.

Chitosan, chitosan derivatives, and chitosan-based nanocomposites: eco-friendly materials for advanced applications (a review)

For many years, chitosan has been widely regarded as a promising eco-friendly polymer thanks to its renewability, biocompatibility, biodegradability, non-toxicity, and ease of modification, giving it enormous potential for future development. As a cationic polysaccharide, chitosan exhibits specific physicochemical, biological, and mechanical properties that depend on factors such as its molecular weight and degree of deacetylation. Recently, there has been renewed interest surrounding chitosan derivatives and chitosan-based nanocomposites. This heightened attention is driven by the pursuit of enhancing efficiency and expanding the spectrum of chitosan applications. Chitosan's adaptability and unique properties make it a game-changer, promising significant contributions to industries ranging from healthcare to environmental remediation. This review presents an up-to-date overview of chitosan production sources and extraction methods, focusing on chitosan's physicochemical properties, including molecular weight, degree of deacetylation and solubility, as well as its antibacterial, antifungal and antioxidant activities. In addition, we highlight the advantages of chitosan derivatives and biopolymer modification methods, with recent advances in the preparation of chitosan-based nanocomposites. Finally, the versatile applications of chitosan, whether in its native state, derived or incorporated into nanocomposites in various fields, such as the food industry, agriculture, the cosmetics industry, the pharmaceutical industry, medicine, and wastewater treatment, were discussed.

"Adsorptive removal of Congo Red dye from its aqueous solution by Ag-Cu-CeO2 nanocomposites: Adsorption kinetics, isotherms, and thermodynamics"

Eliminating synthetic dyes and organic contaminants from water is crucial for safeguarding human health and preserving the environment. In this study, we explored the effectiveness of Ag-Cu-CeO2 nanocomposites as adsorbents to remove Congo Red dye from water. Three compositions of Ag-Cu-CeO2 nanocomposites (10:20:70, 15:15:70, and 20:10:70) have been synthesized by the aqueous coprecipitation method. A comprehensive analysis was performed by different techniques including X-ray diffraction, Fourier transform infrared spectroscopy, BET surface area determination, Thermogravimetric analysis, Scanning electron microscopy, and TEM. The synthesized nanocomposites have a dimension of 5 ± 1 nm and a high surface area (51.832-78.361 m2g-1). Among these, the nanocomposite with composition 15:15:70 showed the highest adsorption capacity of 4.71 mg/g adsorption (96.83 % removal) from the 0.8 × 10-4 M (55.6 mg/l) Congo Red solution at pH values of 2 at 20 °C with contact time of 3h. The adsorption data is best fitted in the Freundlich adsorption isotherm and pseudo-second-order kinetic model. The negative values of enthalpy variation (-27.57, -26.43, and -16.73 kJ/mol) demonstrated that the adsorption was spontaneous and exothermic. The cycling run showed a mere 12 % deactivation after five cycles of use thus indicating that Ag-Cu-CeO2 nanocomposites hold great potential as effective and eco-friendly adsorbents to remove Congo Red from water.

Biosorption of Escherichia coli Using ZnO-Trimethyl Chitosan Nanocomposite Hydrogel Formed by the Green Synthesis Route

In this study, we tested the biosorption capacity of trimethyl chitosan (TMC)-ZnO nanocomposite (NC) for the adsorptive removal of Escherichia coli (E. coli) in aqueous suspension. For the formation of ZnO NPs, we followed the green synthesis route involving Terminalia mantaly (TM) aqueous leaf extract as a reducing agent, and the formed ZnO particles were surface-coated with TMC biopolymer. On testing of the physicochemical characteristics, the TM@ZnO/TMC (NC) hydrogel showed a random spherical morphology with an average size of 31.8 ± 2.6 nm and a crystal size of 28.0 ± 7.7 nm. The zeta potential of the composite was measured to be 23.5 mV with a BET surface area of 3.01 m² g^-1. The spectral profiles of TM@ZnO/TMC NC hydrogel on interaction with Escherichia coli (E. coli) revealed some conformational changes to the functional groups assigned to the stretching vibrations of N-H, C-O-C, C-O ring, and C=O bonds. The adsorption kinetics of TM@ZnO/TMC NC hydrogel revealed the pseudo-second-order as the best fit mechanism for the E. coli biosorption. The surface homogeneity and monolayer adsorption of the TM@ZnO/TMC NC hydrogel reflects majorly the entire adsorption mechanism, observed to display the highest correlation for Jovanovic, Redlich-Peterson, and Langmuir's isotherm models. Further, with the use of TM@ZnO/TMC NC hydrogel, we measured the highest adsorption capacity of E. coli to be 4.90 × 10 mg g^-1, where an in-depth mechanistic pathway was proposed by making use of the FTIR analysis.

Role of silk nanocrystal (SNC)-ZnO as an antibacterial nucleating nanohybrid for a patterned mimic poly(lactic acid) based nanofabric

This new investigation deals with the synthesis of an organic-inorganic nanohybrid using SNC with magnificent flower bud-shaped ZnO, termed SNC-ZnO by precipitation method. The nanohybrid (with concentrations 1 wt%, 3 wt%, and 5 wt%) was in situ incorporated into the PLA matrix to prepare the electrospun solution. The functionalized PLA composite nanofibres produced by electrospinning with SNC-ZnO nanohybrid were systematically studied using different structural and morphological analyses to meet the challenging processing requirements. The FESEM analysis gives an average diameter of nanofibres 246 ± 10.2 nm where nanohybrid tends to adhere on the surface of the PLA nanofabric increasing hydrophobicity up to water contact angle 135.3 ± 0.25 °C with 5 wt% nanohybrid incorporation. The nanofabric has significant antibacterial activity against E.Coli and S.Aureus bacteria. Further, an extensive study has been made on thermally stipulated processes using DSC on non-isothermal crystallization kinetics using different models: Avrami, Ozawa, Mo, and Tobin. The results revealed sites for heterogeneous nucleation and improvement in crystallinity, t_1/2, and nucleation effects due to the incorporation of crystalline nanohybrid in PLA nanofibres. Further, the Avrami plot has confirmed both primary and secondary crystallization processes thereby considering its potential to utilize functionalized PLA nanofabric for applications in protective textile.

Removal of anionic and cationic dyes using porous chitosan/carboxymethyl cellulose-PEG hydrogels: Optimization, adsorption kinetics, isotherm and thermodynamics studies

Chitosan (CS)/carboxymethyl cellulose (CMC) porous hydrogels chemically crosslinked by epichlorohydrin were synthesized using polyethylene glycol (PEG) as a pore-forming agent for anionic (Congo red, CR) and cationic (methylene blue, MB) dyes removal from aqueous solutions. The swelling ratio of hydrogels prepared with 2 % CS and 2 % CMC (CS₂/CMC₂) exhibited optimal performance at different pHs. The addition of PEG into hydrogels (denoted as CS₂/CMC₂-PEG_1.25) exhibited a significantly higher adsorption for CR and MB, increasing from 117.83 to 159.12 mg/g and 110.2 to 136 mg/g, respectively. The comprehensive analyses of Fourier transform infrared spectroscopy, thermalgravimetric study and scanning electron microscopy showed that CS₂/CMC₂-PEG_1.25 hydrogels became more porous with no significant changes in intermolecular and intramolecular interactions, compared with CS₂/CMC₂ hydrogels. The adsorption process for CR and MB conformed to the pseudo-second-order and pseudo-first-order kinetics models, respectively. The results of adsorption isotherm for CR followed both Freundlich and Langmuir models with the maximum adsorption capacities of 1053.88 mg/g, whereas the isotherm for MB fitted the Langmuir model better with the maximum adsorption capacities of 331.72 mg/g. The thermodynamic study results proved that the CR and MB adsorption by hydrogels was spontaneous, but the CR adsorption was endothermic and the MB adsorption was exothermic.

Synthesis of novel chitosan Schiff base and its ZnO nanocomposite for removal of synthetic dye, antimicrobial, and cytotoxicity activity

In this work, a novel chitosan Schiff base 4-(2-Hydroxyaniline)pent-3-en-2-one chitosan (2-HyA-CS) and its ZnO nanocomposite (2-HyA-CS/ZnO) were sensitized and characterized by appropriate methods; FTIR, XRD, Elemental analysis, SEM, TEM and TGA. The result of characterization methods confirms the preparation of 2-HyA-CS and 2-HyA-CS/ZnO. The SEM images reveal that chitosan, 2-HyA-CS, and 2-HyA-CS/ZnO have a varied roughness and porous surfaces. The reason for this difference was attributed to the formation of Schiff base 2-HyA-CS and the presence of ZnO nanoparticles in 2-HyA-CS/ZnO. The patterns of XRD and FTIR confirm the formation of 2-HyA-CS and 2-HyA-CS/ZnO. The degree of substitution (DS) of modified chitosan 2-HyA-CS was calculated using Elemental analysis and FTIR.ATR, it was found to be 74%. The adsorption efficiency of the produced adsorbents was compared with pure chitosan to remove of Remazol Brilliant Blue R (RBBR) from an aqueous medium and antimicrobial activity. The removal percentage of RBBR by chitosan, 2-HyA-CS, and 2-HyA-CS/ZnO are 47.12%, 91.9%, and 96.56%, respectively with the following order: 2-HyA-CS/ZnO > 2-HyA-CS > chitosan. Their antimicrobial activities were studied against two Gram negative bacteria ( E. coli and P. aeruginosa), two Gram positive bacteria ( S. aureus and B. cereus) and ( C. albicans) as a yeast strain, the inhibitory zone measurements revealed that the activity of 2-HyA-CS/ZnO is excellent and higher than 2-HyA-CS and pure chitosan. The cytotoxicity of the prepared compound 2-HyA-CS and 2-HyA-CS/ZnO along with pure chitosan was estimated against two human cancer cells MCF-7 cells and HepG-2 cells, the result indicates that 2-HyA-CS/ZnO having higher Inhibitory activity against both MCF-7 and HepG-2 cells with 53.5 ± 2.86 and 27.4 ± 1.23 µg/mL respectively and 2-HyA-CS possessing moderate Inhibitory activity against both MCF-7 and HepG-2 cancer cells with IC50 = 216.5 ± 7.48 and 135.6 ± 6.49 µg/ml respectively.

Chitosan-Functionalized Hydroxyapatite-Cerium Oxide Heterostructure: An Efficient Adsorbent for Dyes Removal and Antimicrobial Agent

The current research intended to employ a facile and economical process, which is also ecofriendly to transform camel waste bones into novel heterostructure for cleansing of diverse waste waters. The bones of camel were utilized for preparation of hydroxyapatite by hydrothermal method. The prepared hydroxyapatite was applied to the synthesis of cerium oxide-hydroxyapatite coated with natural polymer chitosan (CS-HAP-CeO₂) heterostructure. Being abundant natural polymer polysaccharide, chitosan possesses exceptional assets such as accessibility, economic price, hydrophilicity, biocompatibility as well as biodegradability, therefore style it as an outstanding adsorbent for removing colorant and other waste molecules form water. This heterostructure was characterized by various physicochemical processes such as XRD, SEM-EDX, TEM, and FT-IR. The CS-HAP-CeO₂ was screened for adsorption of various industrially important dyes, viz., Brilliant blue (BB), Congo red (CR), Crystal violet (CV), Methylene blue (MB), Methyl orange (MO), and Rhodamine B (RB) which are collective pollutants of industrial waste waters. The CS-HAP-CeO₂ demonstrated exceptional adsorption against CR dye. The adsorption/or removal efficiency ranges are BB (11.22%), CR (96%), CV (28.22%), MB (47.74%), MO (2.43%), and RB (58.89%) dyes. Moreover, this heterostructure showed excellent bacteriostatic potential for E. coli, that is liable for serious waterborne diseases. Interestingly, this work revealed that the incorporation of cerium oxide and chitosan into hydroxyapatite substantially strengthened antimicrobial and adsorption capabilities than those observed in virgin hydroxyapatite. Herein, we recycled the unwanted camel bones into a novel heterostructure, which assists to reduce water pollution, mainly caused by the dye industries.

Preparation of a Chitosan-Lead Composite Carbon Aerogel and Its Catalytic Thermal Decomposition Performance on Ammonium Perchlorate

Chitosan-lead (CS-Pb) carbon aerogels were prepared by ionic cross-linking and high-temperature carbonization using chitosan (CS) as the carbon precursor. The obtained carbon aerogels were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffractometry (XRD), and X-ray photoelectron spectroscopy (XPS). The obtained aerogels have a 3D structure and a large surface area, which can effectively prevent the agglomeration phenomenon of metals. Differential thermal analysis (DTA) was used to analyze the catalytic performance of a carbon aerogel for ammonium perchlorate (AP). The results showed that the CS-Pb carbon aerogel reduced the peak temperature of AP pyrolysis from 703.9 to 627.7 K. According to the Kissinger method calculations, the E_a of AP decomposition decreased about 27.2 kJ/mol. The TG data at different warming rates were analyzed by the Flynne-Walle-Ozawa (FWO) and Kissinger-Akahira-Sunose (KAS) methods, which are two of the isoconversion methods, and the activation energies of AP and AP+CS-Pb-3.5 were calculated. Between the conversion degrees (α) of 0.1 and 0.9, the E_a values obtained by the two isoconversion methods are similar and have a certain match. Also, the two isoconversion methods confirm Kissinger's calculation. Finally, thermogravimetry-mass spectrometry (TG-MS) was used to monitor the gases generated during the thermal decomposition of the AP+CS-Pb-3.5 system in real time.

Graphene Oxide/Fe3O4/Chitosan−Coated Nonwoven Polyester Fabric Extracted from Disposable Face Mask for Enhanced Efficiency of Organic Dye Adsorption

Owing to the COVID-19 pandemic, huge amounts of disposable face masks have been manufactured and used, and these discarded face masks have to be treated. In this study, we propose a simple approach for reusing the nonwoven polyester fabric (NWPF) from disposable face masks. In this approach, NWPF is utilized as a supporter for coating of a layer of graphene oxide/Fe3O4/chitosan (GFC) to form a GFC/NWPF adsorbent at room temperature via a simple spray coating method that does not require any solvent. The specific properties of GFC, NWPF, and the GFC/NWPF adsorbent were analysed via X-ray diffraction, transmission electron microscopy, ultraviolet–visible spectroscopy, vibrating sample magnetometry, and field-emission scanning electron microscopy. Results showed that the presence of NWPF enhanced the adsorption capacity of GFC towards organic dyes. At high concentrations of the organic dyes, the adsorption efficiency of the GFC/NWPF adsorbent to the dyes reached 100% within 24 h. The adsorption capacity ( $q_{\max }$ ) of the GFC/NWPF adsorbent to methylene blue, methyl orange, Congo red, and moderacid red was 54.795, 87.489, 88.573, and 29.010 mg g−1, respectively, which were considerably higher than that of bulk GFC (39.308, 82.304, 52.910, and 21.249 mg g−1, respectively).

A State-of-the-Art Review on Biowaste Derived Chitosan Biomaterials for Biosorption of Organic Dyes: Parameter Studies, Kinetics, Isotherms and Thermodynamics

Chitosan is a second-most abundant biopolymer on earth after cellulose. Its unique properties have recently received particular attention from researchers to be used as a potential biosorbent for the removal of organic dyes. However, pure chitosan has some limitations that exhibit lower biosorption capacity, surface area and thermal stability than chitosan composites. The reinforcement materials used for the synthesis of chitosan composites were carbon-based materials, metal oxides and other biopolymers. This paper reviews the effects of several factors such as pH, biosorbent dosage, initial dye concentration, contact time and temperature when utilizing chitosan-based materials as biosorbent for removing of organic dyes from contaminated water. The behaviour of the biosorption process for various chitosan composites was compared and analysed through the kinetic models, isotherm models and thermodynamic parameters. The findings revealed that pseudo-second-order (PSO) and Langmuir isotherm models were best suited for describing most of the biosorption processes or organic dyes. This indicated that monolayer chemisorption of organic dyes occurred on the surface of chitosan composites. Most of the biosorption processes were endothermic, feasible and spontaneous at the low temperature range between 288 K and 320 K. Therefore, chitosan composites were proven to be a promising biosorbent for the removal of organic dyes.

Biosynthesis of chitosan-coated iron oxide (Fe3O4) hybrid nanocomposites from leaf extracts of Brassica oleracea L. and study on their antibacterial potentials

In this study, we prepared chitosan (CS)-coated iron oxide (Fe₃O₄) nanocomposites (NCs) by employing the aqueous leaf extract of Brassica oleracea L. and evaluated its antimicrobial potential. The characterization of hybrid CS-Fe₃O₄ NCs was performed using Fourier-transform infrared spectroscopy (FTIR) analysis to evaluate the chemical bonding of chitosan to nanoparticles (NPs). X-ray photoelectron spectroscopy (XPS) studies revealed the presence of oxidation state elements Fe 2p, O 1s, N 1s, and C 1s, and the zeta potential analysis was found to have well-colloidal stability (+ 76.9 mV) of NCs. Transmission electron microscopy (TEM) analysis determined that CS-Fe₃O₄ NCs were spherical with an average particle size of 27 nm. The X-ray diffractometer (XRD) spectrum ascertained the crystallinity of the hybrid NCs and the vibrating sample magnetometer (VSM) inferred the ferromagnetic behavior of the synthesized NCs. Furthermore, the significant antibacterial efficacy of NPs was demonstrated against foodborne bacterial pathogens, such as Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli), and the highest zone of inhibition was observed to be 11.5 mm and 13.5 mm in CS-Fe₃O₄ NCs, respectively. In comparison with Fe₃O₄ NPs, synergistic impacts of CS-Fe₃O₄ NCs displayed great antibacterial potential as exhibited by a clearly enlarged zone. Thus, CS-Fe₃O₄ NCs could be used as efficacious antimicrobial agents in food packaging and food preservation fields.

A journey to the world of fascinating ZnO nanocomposites made of chitosan, starch, cellulose, and other biopolymers: Progress in recent achievements in eco-friendly food packaging, biomedical, and water remediation technologies

Green chemistry or in other words "green world" is referred to a sustainable environment using biocompatible, biodegradable, renewable, economical, and simple materials, and methods. Without any exaggeration, the exceptional chemical and physical properties of ZnO bionanocomposites beside various utilizations, make it vital materials in research and green chemistry field. Biocompatible ZnO nanoparticles with fascinating antimicrobial, physicochemical, as well as photocatalytic performance could be applied as a prominent candidate to reinforce diverse biopolymer matrixes, for instance, chitosan, starch, cellulose, gelatin, alginate, poly(hydroxyalkanoates), carrageenan, and so on. With a combination of advantageous properties of these materials, they could be illustrated specific utilizations in different areas. In this regard, the following context focuses on highlighting the recent achievements of this category of material on three important and widely used scopes: eco-friendly food packaging, biomedical specially wound dressings, and water remediation technologies.