CuO embedded chitosan spheres as antibacterial adsorbent for dyes

Facile Synthesis of a Crystalline Zinc Sulfide/Chitosan Biopolymer Nanocomposite: Characterization and Application for Photocatalytic Degradation of Textile Dyes and Anticancer Activity

In the present study, we have synthesized a zinc sulfide/chitosan (ZS/CS) nanocomposite by utilizing simple, economical, and environmentally friendly methods. The synthesized nanomaterials were characterized by different analytical techniques such as XRD, FE-SEM, EDS, and FTIR to determine the phase structure, morphology, and elemental composition. FTIR spectroscopy was used to confirm the functional groups of the synthesized zinc sulfide (ZS) nanoparticles and ZS/CS composite. Besides, the optical properties of the as-synthesized nanocomposite was analyzed by a UV-visible spectrophotometer, and the estimated band gap energy is ∼3.03 eV. The photocatalytic efficiency of the synthesized ZS/CS nanocomposite was investigated against two textile dyes, Crystal Violet (CV) and Acid Red-I (AR-I), under UV-visible light irradiation. The nanocomposite showed excellent photocatalytic activity against the dyes, and photodegradation was estimated to be about 93.44 and 90.67% for CV and AR-I, respectively. The nanocomposite was reused for three consecutive cycles. The results revealed that the photocatalyst displayed good reusability during the photocatalytic decomposition and thus is considered a cost-effective and promising photocatalyst in degrading dye pollutants. The kinetic study proved that the pseudo-first-order reaction kinetics was followed by the degradation process. We also examined the anticancer activity of ZS and ZS/CS against human breast and myelogenous leukemia cancer cell lines, namely, MCF-7 and K-562, and the half minimal inhibitory concentrations were found to be less than 50 μg/mL.

Development of silver-doped copper oxide and chitosan nanocomposites for enhanced antimicrobial activities

Antimicrobial resistance (AMR) has emerged as a significant and pressing public health concern, posing serious challenges to effectively preventing and treating persistent diseases. Despite various efforts made in recent years to address this problem, the global trends of AMR continue to escalate without any indication of decline. As AMR is well-known for antibiotics, developing new materials such as metal containing compounds with different mechanisms of action is crucial to effectively address this challenge. Copper, silver, and chitosan in various forms have demonstrated significant biological activities and hold promise for applications in medicine and biotechnology. Exploring the biological properties of these nanoparticles is essential for innovative therapeutic approaches in treating bacterial and fungal infections, cancer, and other diseases. To this end, the present study aimed to synthesize silver@copper oxide (Ag@CuO) nanoparticles and its chitosan nanocomposite (Chi-Ag@CuO) to investigate their antimicrobial efficacy. Various established spectroscopic and microscopic methods were employed for characterization purposes, encompassing scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). Subsequently, the antimicrobial activity of the nanoparticles was assessed through MIC (minimum inhibitory concentration), MBC (minimum bactericidal concentration), and well-disk diffusion assays against Pseudomonas aeruginosa, Acinetobacter baumannii Staphylococcus aureus, Staphylococcus epidermidis, and Candida albicans. The size of the CuO-NPs, Ag@CuO, and Chi-Ag@CuO NPs was found to be 70-120 nm with a spherical shape and an almost uniform distribution. The nanocomposites were found to possess a minimum inhibitory concentration (MIC) of 5 μg/mL and a minimum bactericidal concentration (MBC) of 250 μg/mL. Moreover, these nanocomposites generated varying clear inhibition zones, with diameters ranging from a minimum of 9 ± 0.5 mm to a maximum of 25 ± 0.5 mm. Consequently, it is evident that the amalgamation of copper-silver-chitosan nanoparticles has exhibited noteworthy antimicrobial properties in the controlled laboratory environment, surpassing the performance of other types of nanoparticles.

Multifunctional Ag2O/chitosan nanocomposites synthesized via sol-gel with enhanced antimicrobial, and antioxidant properties: A novel food packaging material

In this study, a single step in situ sol-gel method was used to syntheses nanocomposite films using chitosan (CS) as the basis material, with the addition of silver oxide nanoparticles (Ag2O) at several weight percentages (5 %, 10 %, and 15 % Ag2O/CS). The structural characteristics of Ag2O/CS films were investigated using a range of analytical techniques. The presence of the primary distinctive peaks of chitosan was verified using FTIR spectra analysis. However, a minor displacement was observed in these peaks due to the chemical interaction occurring with silver oxide molecules. XRD analysis demonstrated a significant increase in the crystallinity of chitosan when it interacted with metal oxide nanoparticles. Furthermore, it is believed that the interaction between silver oxide and the active binding sites of chitosan is responsible for the evenly dispersed clusters shown in the micrographs of the chitosan surface, as well as the random aggregations within the pores. EDS technique successfully identified the presence of distinctive silver signals within the nanocomposite material, indicating the successful absorption of silver into the surface of the polymer. The developed Ag2O/CS nanocomposite showed promising antibacterial activity against Gram-negative (Escherichia coli and Pseudomonas aeruginosa) and Gram-positive bacteria (Bacillus subtilis, Enterococcus faecalis and Staphylococcus aureus). Also, Ag2O/CS nanocomposite exhibited marked antifungal activity against Candida albicans, Aspergillus flavus, A. fumigatus, A. niger, and Penicillium chrysogenum. The antioxidant activity of the developed nanocomposite films was studied by ABTS radical scavenging. The highest antioxidant and antibacterial properties were achieved by including 15 % silver oxide into the chitosan. Therefore, our finding indicate that chitosan‑silver oxide nanocomposites exhibits significant potential as a viable material for application in several sectors of the food packaging industry.

Quantitative Determination of Metal Ion Adsorption on Cellulose Nanocrystals Surfaces

Nanocellulose is a bio-based material that holds significant potential in the field of water purification. Of particular interest is their potential use as a key sorbent material for the removal of metal ions from solution. However, the structure of metal ions adsorbed onto cellulose surfaces is not well understood. The focus of this work is to determine quantitatively the three-dimensional distribution of metal ions of different valencies surrounding negatively charged carboxylate functionalized cellulose nanocrystals (CNCs) using anomalous small-angle X-ray scattering (ASAXS). These distributions can affect the water and ionic permeability in these materials. The data show that increasing the carboxylate density on the surface of the CNCs from 740 to 1100 mmol/kg changed the nature of the structure of the adsorbed ions from a monolayer into a multilayer structure. The monolayer was modeled as a Stern layer around the CNC nanoparticles, whereas the multilayer structure was modeled as a diffuse layer on top of the Stern layer around the nanoparticles. Within the Stern layer, the maximum ion density increases from 1680 to 4350 mmol of Rb+/(kg of CNC) with the increase in the carboxylate density on the surface of the nanoparticles. Additionally, the data show that CNCs can leverage multiple mechanisms, such as electrostatic attraction and the chaotropic effect, to adsorb ions of different valencies. By understanding the spatial organization of the adsorbed metal ions, the design of cellulose-based sorbents can be further optimized to improve the uptake capacity and selectivity in separation applications.

Biodegradable Polymers and Polymer Composites with Antibacterial Properties

Antibiotic resistance is one of the greatest threats to global health and food security today. It becomes increasingly difficult to treat infectious disorders because antibiotics, even the newest ones, are becoming less and less effective. One of the ways taken in the Global Plan of Action announced at the World Health Assembly in May 2015 is to ensure the prevention and treatment of infectious diseases. In order to do so, attempts are made to develop new antimicrobial therapeutics, including biomaterials with antibacterial activity, such as polycationic polymers, polypeptides, and polymeric systems, to provide non-antibiotic therapeutic agents, such as selected biologically active nanoparticles and chemical compounds. Another key issue is preventing food from contamination by developing antibacterial packaging materials, particularly based on degradable polymers and biocomposites. This review, in a cross-sectional way, describes the most significant research activities conducted in recent years in the field of the development of polymeric materials and polymer composites with antibacterial properties. We particularly focus on natural polymers, i.e., polysaccharides and polypeptides, which present a mechanism for combating many highly pathogenic microorganisms. We also attempt to use this knowledge to obtain synthetic polymers with similar antibacterial activity.

A review of the main methods for composite adsorbents characterization

Adsorption is a promising technology for removing several contaminants from aqueous matrices. In the last years, researchers worldwide have been working on developing composite adsorbents to overcome some limitations and drawbacks of conventional adsorbent materials, which depend on various factors, including the characteristics of the adsorbents. Therefore, it is essential to characterize the composite adsorbents to describe their properties and structure and elucidate the mechanisms, behavior, and phenomenons during the adsorption process. In this sense, this work aimed to review the main methods used for composite adsorbent characterization, providing valuable information on the importance of these techniques in developing new adsorbents. In this paper, we reviewed the following methods: X-Ray diffraction (XRD); spectroscopy; scanning electron microscopy (SEM); N2 adsorption/desorption isotherms (BET and BJH methods); thermogravimetry (TGA); point of zero charge (pHPZC); elemental analysis; proximate analysis; swelling and water retention capacities; desorption and reuse.

Fabrication of 3D Gelatin Hydrogel Nanocomposite Impregnated Co-Doped SnO2 Nanomaterial for the Catalytic Reduction of Environmental Pollutants

In the catalytic reduction of various environment pollutants, cobalt-doped tin oxide, i.e., Co-SnO₂ intercalated gelatin (GL) hydrogel nanocomposite was prepared via direct mixing of Co-SnO₂ doped with GL. Then, it was crosslinked internally using formaldehyde within a viscous solution of gelatin polymer, which led to the formation of GL/Co-SnO₂ hydrogel nanocomposite. GL/Co-SnO₂ hydrogel nanocomposite was fully characterized by using field-emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDX), powder X-ray diffraction (XRD), and attenuated total reflection–Fourier transform infrared spectroscopy (ATR-FTIR). The FESEM images indicate that the Co-SnO₂ composite has a spherical structure on the GL matrix while EDX elucidates the elemental composition of each atom in the crosslinked GL/Co-SnO₂ hydrogel nanocomposite. The GL/Co-SnO₂ nanocomposite was checked for the reduction of various pollutants, including 2-nitro-phenol (2-NP), 2,6-dinitro-phenol (2,6-DNP), 4-nitro-phenol (4-NP), Congo red (CR), and methyl orange (MO) dyes with a strong sodium borohydride (NaBH₄) reducing agent. The GL/Co-SnO₂ nanocomposite synergistically reduced the MO in the presence of the reducing agent with greater reduction rate of 1.036 min⁻¹ compared to other dyes. The reduction condition was optimized by changing various parameters, such as the catalyst amount, dye concentration, and the NaBH₄ amount. Moreover, the GL/Co-SnO₂ nanocomposite catalyst can be easily recovered, is recyclable, and revealed minimal loss of nanomaterials.

Catalytic Reduction of Environmental Pollutants with Biopolymer Hydrogel Cross-Linked Gelatin Conjugated Tin-Doped Gadolinium Oxide Nanocomposites

In the present study, a biopolymer nanocomposite hydrogel based on gelatin and tin-doped gadolinium oxide (Sn-Gd₂O₃@GH) was prepared for the efficient reduction of water pollutants. The method of Sn-Gd₂O₃@GH preparation consisted of two steps. A Sn-Gd₂O₃ nanomaterial was synthesized by a hydrothermal method and mixed with a hot aqueous solution (T > 60 °C) of gelatin polymer, followed by cross-linking. Due to the presence of abundant functional groups on the skeleton of gelatin, such as carboxylic acid (–COOH) and hydroxyl (–OH), it was easily cross-linked with formaldehyde. The structure, morphology, and composition of Sn-Gd₂O₃@GH were further characterized by the FESEM, XRD, EDX, and FTIR techniques. The FESEM images located the distribution of the Sn-Gd₂O₃ nanomaterial in a GH matrix of 30.06 nm. The XRD patterns confirmed the cubic crystalline structure of Gd₂O₃ in a nanocomposite hydrogel, while EDS elucidated the elemental composition of pure Sn-Gd₂O₃ powder and cross-linked the Sn-Gd₂O₃@GH samples. The synthesized Sn-Gd₂O₃@GH nanocomposite was used for the removal of different azo dyes and nitrophenols (NPs). It exhibited an efficient catalytic reduction of Congo red (CR) with a reaction rate of 9.15 × 10⁻¹ min⁻¹ with a strong NaBH₄-reducing agent. Moreover, the Sn-Gd₂O₃@GH could be easily recovered by discharging the reduced (colourless) dye, and it could be reused for a fresh cycle.

A novel core–shell Pd(0)@enSiO2–Ni–TiO2 nanocomposite with a synergistic effect for efficient hydrogenations

The synthesis of a core–shell nano-structured Pd(0)@enSiO2–Ni–TiO2 catalyst for the hydrogenation of nitro-arenes, quinoline and α,β-unsaturated carbonyl compounds was demonstrated.

Metal‐Organic Framework Derived Carbon-Encapsulated Hollow CuO/Cu2O Heterostructure Heterohedron as an Efficient Electrocatalyst for Hydrogen Evolution Reaction

It is of pivotal significance to probe highly efficient, cost-effective and low-cost catalysts for hydrogen evolution reaction. Herein, closely packed carbon-encapsulated CuO/Cu2O heterohedron with heterojunction structure is reported that combines...

Applications of chitin and chitosan based biomaterials for the adsorptive removal of textile dyes from water - A comprehensive review

The presence of pollutants in the water bodies deteriorate the water quality and make it unfit for use. From an environmental perspective, it is essential to develop new technologies for the wastewater treatment and recycling of dye contaminated water. The surface modified chitin and chitosan biopolymeric composites based adsorbents, have an important role in the toxic organic dyes from removal wastewater. The surface modification of biopolymers with various organics and inorganics produces more active sites at the surface of the adsorbent, which enhances dye and adsorbent interaction more reliable. Herein, the work brought in the thought of the application of various chitin and chitosan composites in wastewater remediation and suggested the versatility in composites for the development of rapid, selective and effective removal processes for the detoxification of a variety of organic dyes. It further emphasizes the existing obstruction and impending prediction for the deprivation of dyes via adsorption techniques.

Catalytic reduction of 4-nitrophenol and methylene blue pollutants in water by copper and nickel nanoparticles decorated polymer sponges

In the present study, two catalysts based-on copper and nickel nanoparticles anchored on agarose-coated sponge (Cu-AG-sponge and Ni-AG-sponge) were prepared, respectively. Both catalysts were characterized by analytical techniques of thermogravimetric analysis energy dispersive X-ray spectroscopy (EDX) and scanning electron microscopy (SEM). Spherical Cu and Ni nanoparticles on struts of AG-coated sponge were observed by FESEM and the samples' elemental composition was confirmed by EDX technique. After characterization, the Cu-AG-sponge and Ni-AG-sponge catalysts were tested in 4-nitrophenol (4-NP) and methylene blue dye (MB) reduction in an aqueous medium. The reduction of the 4-NP to 4-aminophenol (4-AP) was achieved up to 95% using the NaBH₄ reductant and Cu-AG-sponge and Ni-AG-sponge catalysts, respectively. Similarly, the rate of reduction of MB was faster for the Cu-AG-sponge as compared to the Ni-AG-sponge which was discussed based-on the catalyst morphology and other factors. The high rate of reactions for the 4-NP and MB reduction suggests that the Cu-AG-sponge and Ni-AG-sponge catalyst possess high catalytic efficiency, low cost and good reusability having the potential to be used in similar other reactions.

Development in nanomembrane-based filtration of emerging contaminants

Recently, the concentration of emerging contaminants is increasing in drinking water sources, industrial wastewater, and reclaimed water. It is not possible to remove the emerging contaminants using conventional methods, and the interest to use nanomembrane-based filtration is getting attention. A nanomembrane-based filtration can be manipulated without the use of any special equipment. Different research findings reported better removal of emerging contaminants has been achieved using nanomembrane-based filtration. Moreover, new developments have been examined and implemented at different levels and are expected to continue. Therefore, this chapter provides a brief overview of recent developments on nanomembrane-based filtration processes in the removal of emerging contaminants from drinking water sources, industrial wastewater, and reclaimed water.

Biomass-Derived Activated Carbon-Supported Copper Catalyst: An Efficient Heterogeneous Magnetic Catalyst for Base-Free Chan-Lam Coupling and Oxidations

Development of heterogeneous catalysts from biomass-derived activated carbon is a challenging task. Biomass-derived activated carbon possesses a large specific surface area, highly porous structure, and good thermal/chemical stability. Magnetic copper catalysts based on biomass-derived activated carbon exhibited good catalytic activity in base-free Chan-Lam coupling and oxidations. Herein, biomass-derived activated carbon was prepared by the carbonization of neem dead leaves (abundant waste biomass) followed by chemical activation with KOH. Such a porous carbon material was used as a low cost and highly efficient support material for the preparation of inexpensive and environmentally benign magnetic catalysts [Cu@KF-C/MFe2O4, M = Co, Cu, Ni, and Zn]. In addition, KF modification was done to impart basic character to the catalyst that can perform C-N coupling under base-free conditions. Initially, Brunauer-Emmett-Teller (BET) analysis of the synthesized catalysts was carried out, which indicated that Cu@KF-C/CoFe2O4 possess more surface area as well as pore volume, and so accounting for the highest activity among the other synthesized catalysts. Further, X-ray photoelectron spectroscopy (XPS) analysis was performed, which inferred that Cu@KF-C/CoFe2O4 contains most of the copper in reduced form, i.e., Cu(0), which is the active species responsible for better catalytic activity toward Chan-Lam coupling reactions as well as oxidation of alcohols and hydrocarbons. The physiochemical properties of the most active catalyst, Cu@KF-C/CoFe2O4, was examined by BET, XPS, Fourier transform infrared Spectroscopy (FTIR), thermogravimetric analysis (TGA), field emission gun scanning electron microscopy (FEG-SEM), high-resolution transmission electron microscopy (HR-TEM), energy dispersive X-ray (EDX) mapping, energy dispersive X-ray (EDX), inductively coupled plasma atomic emission spectroscopy (ICP-AES), powder X-ray diffraction (XRD), and vibrating sample magnetometry (VSM). Moreover, Cu@KF-C/CoFe2O4 shows excellent stability as well as reusability and could be easily separated with the help of an external magnet.

Super adsorption performance of carboxymethyl cellulose/copper oxide-nickel oxide nanocomposite toward the removal of organic and inorganic pollutants

A novel nanocomposite bead based on polymeric matrix of carboxymethyl cellulose and copper oxide-nickel oxide nanoparticles was synthesized, characterized, and applied for adsorptive removal of inorganic and organic contaminants at trace level of part per million (mgL^-1) from aqueous sample. Carboxymethyl cellulose/copper oxide-nickel oxide (CMC/CuO-NiO) adsorbent beads were selective toward the removal of Pb(II) among other metal ions. The removal percentage of Pb(II) was more than 99% with 3 mgL^-1. The waste beads after Pb (II) adsorption (Pb@CMC/CuO-NiO) and CMC/CuO-NiO nanocomposite beads were employed as adsorbents for removing of various dyes. It was found that Pb@CMC/CuO-NiO can be reused as adsorbent for the removal of Congo Red (CR), while CMC/CuO-NiO nanocomposite beads were more selective for removal of Eosin Yellow (EY) from aqueous media. The adsorption of CR and EY was optimized, and the removal percentages were 93% and 96.4%, respectively. The influence of different parameters was studied on the uptake capacity of Pb(II), CR, and EY, and lastly, the CMC/CuO-NiO beads exhibited responsive performance in relation to pH and other parameters. Thus, the prepared CMC/CuO-NiO beads were found to be a smart material which is effective and played super adsorption performance in the removal of Pb(II), CR, and EY from aqueous solution. These features make CMC/CuO-NiO beads suitable for numerous scientific and industrial applications and may be used as an alternative to high-cost commercial adsorbents.

Comparative efficacy of biogenic zinc oxide nanoparticles synthesized by Pseudochrobactrum sp. C5 and chemically synthesized zinc oxide nanoparticles for catalytic degradation of dyes and wastewater treatment

Discharge of untreated textile wastewaters loaded with dyes is not only contaminating the soil and water resources but also posing a threat to the health and socioeconomic life of the people. Hence, there is a need to devise the strategies for effective treatment of such wastewaters. The present study reports the catalytic potential of biogenic ZnO nanoparticles (ZnO NPs) synthesized by using a bacterial strain Pseudochrobactrum sp. C5 for degradation of dyes and wastewater treatment. The catalytic potential of the biogenic ZnO NPs for degradation of dyes and wastewater treatment was also compared with that of the chemically synthesized ones. The characterization of the biogenic ZnO NPs through FT-IR, XRD, and field emission scanning electron microscopy (FESEM) indicated that these are granular agglomerated particles having a size range of 90-110 nm and zeta potential of -27.41 mV. These catalytic NPs had resulted into almost complete (> 90%) decolorization of various dyes including the methanol blue and reactive black 5. These NPs also resulted into a significant reduction in COD, TDS, EC, pH, and color of two real wastewaters spiked with reactive black 5 and reactive red 120. The findings of this study suggest that the biosynthesized ZnO NPs might serve as a potential green solution for treatment of dye-loaded textile wastewaters.

Eggshell membranes coated chitosan decorated with metal nanoparticles for the catalytic reduction of organic contaminates

This study focusses on the effect of chitosan coating with eggshell membranes for the reduction of different organic pollutants. Chickens eggs were collected from the local market and utilized to extract the enrich eggshell membranes (ESM). The chicken eggshell membranes are abundant waste material which is inexpensive and illustrates remarkable physiognomies for many possible applications. Fresh fibers/strips coated by chitosan (CS) were prepared by mixing the eggshell membranes with CS solution (2 wt%/v) in different proportions i.e., 10 %, 30 %, 50 %, 60 %, 70 %, 80 %, and 90 %. These strips were then templated with copper and iron metal nanoparticles by putting them in their metal ions aqueous solution to adsorb the metals ions and were then reduced to zero-valent metal nanoparticles (MNPS) by using NaBH₄ aqueous solution. These prepared materials (MNPS@ESM-CS) were characterized by using XRD, XPS, FE-SEM, and EDS to confirm the successful preparation of MNPs over the surface of ESM coated with CS. Afterwards, these prepared materials were investigated as a catalyst for the reduction of different organic pollutants, such as 4-nitroaniline (4-NA), 4-nitrophenol (4-NP) and methylene blue (MB) dye. The catalytic efficiency of ESM was enhanced 5.7-fold by adding only 20 % CS solution. It was observed that Cu@ESM-CS-80 % took 7 min for reduction of 4-NA, 6 min for 4-NP, and 7 min for MB dye. The reusability of the catalytic strip was also investigated for four cycles and found efficient and can be easily recovered by simply pulling it from the reaction mixture.

Copper on chitosan-modified cellulose filter paper as an efficient dip catalyst for ATRP of MMA

Achieving an efficient catalyst in the ATRP system with a simple design, preparation from available materials, and high recyclability is a significant challenging issue. To attain the goal, herein, we used chitosan (CS)-modified cellulose filter paper (FP) as a green support for the synthesis of dip catalyst. The preparation of this catalyst involved surface treatment of the FP strips by CS coating through a dipping method, which increased the affinity of the substrate for adsorbing copper ions in the next step. The Cu@CS-FP catalyst was prepared without the requirement of any ligands. The synthesized dip-catalyst, in the form of the strips, was employed for the first time in the ATRP reaction of methyl methacrylate to assay catalytic activity. Catalytic insertion/ removal (ON/OFF) experiments were carried out during the polymerization. A reasonable control over the molecular weight with high conversion (68%) and polydispersity index of 1.32 under mild reaction conditions were obtained. Significantly, because of the facile separation of the catalyst, the amount of copper that remained in the polymer was very low (2.7 ppm). Also, the recyclability of the catalyst was investigated for five runs. The conversion in the final run was 64% without a loss of catalyst efficiency.

Synthesis of zero-valent Au nanoparticles on chitosan coated NiAl layered double hydroxide microspheres for the discoloration of dyes in aqueous medium

The catalyst activity of the nano Au was largely dependent on the particle size and the structure of the supported matrix to avoid particle agglomeration. Chitosan (CS) and CS coated layered double hydroxide of NiAl (LDH) microsphere were designed through a simple and an economic casting method. The CS and LDH microsphere were used for the impregnation and support of Au NPs and represented as Au/CS and Au/LDH and used for the sole and concurrent discoloration of methylene blue (MB) and rhodamine B (RB) dyes. The aim of the incorporation of NiAl-LDH to the CS host polymer is to increase the binding capacity of CS with Au NPs to make it more stable. The Au/LDH displaying stronger catalyst activity for both dyes discoloration, while found highly selective for MB dye. The high catalyst activity of Au/LDH is due to their small crystallite size which is 1.02 nm compared to 6.75 nm in Au/CS derived from Scherer's equation. The k_app value based on zero-order kinetics was higher with Au/LDH against MB and RB dyes which are 3.5 × 10^-1 and 1.4 × 10^-1 min^-1 respectively.

Photocatalytic degradation of crystal violet dye under sunlight by chitosan-encapsulated ternary metal selenide microspheres

Organic dyes that are extensively released in wastewater from various industries remain the priority concern in the modern world. Therefore, a novel catalyst, bismuth-iron selenide, was prepared through the solvothermal process for photocatalytic degradation of a carcinogenic crystal violet dye. The catalyst was supported with chitosan to form iron-bismuth selenide-chitosan microspheres (BISe-CM). The synthesized catalyst was composed of iron, bismuth, and selenium in a definite proportion based on EDX analysis. FTIR analysis confirmed the synthesis of BISe-CM from characteristic bands of metal selenium bond as well as the typical bands of chitosan. SEM analysis illustrated the average diameter of the barren catalyst to be 54.8 nm, while the average size of the microspheres was 982.5 um. The BISe-CM has the surface of a pore with an average size of 0.5 um. XRD analysis revealed that the synthesized catalyst was composed of Fe₃Se₄ and Bi₂Se₃. The prepared catalyst showed better degradation efficiency for crystal violet dye at optimized conditions under solar irradiation. Employing 0.2 g of BISe-CM resulted in complete degradation for 30 ppm of crystal violet dye in 150 min at pH 8.0. The reusability of the catalyst up to four consecutive times makes it a more attractive and practical candidate. Moreover, the catalyst followed pseudo-first-order kinetics in the decontamination of crystal violet. Conclusively, the novel photocatalyst showed the best decolorizing property of crystal violet under sunlight irradiation and could be a suitable alternative for dye decontamination from wastewater.

Starch, cellulose, pectin, gum, alginate, chitin and chitosan derived (nano)materials for sustainable water treatment: A review

Natural biopolymers, polymeric organic molecules produced by living organisms and/or renewable resources, are considered greener, sustainable, and eco-friendly materials. Natural polysaccharides comprising cellulose, chitin/chitosan, starch, gum, alginate, and pectin are sustainable materials owing to their outstanding structural features, abundant availability, and nontoxicity, ease of modification, biocompatibility, and promissing potentials. Plentiful polysaccharides have been utilized for making assorted (nano)catalysts in recent years; fabrication of polysaccharides-supported metal/metal oxide (nano)materials is one of the effective strategies in nanotechnology. Water is one of the world's foremost environmental stress concerns. Nanomaterial-adorned polysaccharides-based entities have functioned as novel and more efficient (nano)catalysts or sorbents in eliminating an array of aqueous pollutants and contaminants, including ionic metals and organic/inorganic pollutants from wastewater. This review encompasses recent advancements, trends and challenges for natural biopolymers assembled from renewable resources for exploitation in the production of starch, cellulose, pectin, gum, alginate, chitin and chitosan-derived (nano)materials.

The in situ fabrication of ZIF-67 on titania-coated magnetic nanoparticles: a new platform for the immobilization of Pd(ii) with enhanced catalytic activity for organic transformations

The synthesis of a magnetic zeolitic-imidazolate-framework-67-supported Pd catalyst was demonstrated, and its catalytic activity for oxidation, reduction, and the oxidative deprotection of oximes was studied.

Catalytic potential of cobalt oxide and agar nanocomposite hydrogel for the chemical reduction of organic pollutants

In this study, cobalt oxide nanoparticles (Co₃O₄ NPs) were synthesized by precipitation method from cobalt sulphate solution with basic pH, followed by calcination. The ex-situ synthesized Co₃O₄ NPs were mixed with hot agar (AG) aqueous solution. The preparation of AG- Co₃O₄ nanocomposite hydrogel was carried out by self-association method promoted by thermal denaturation. The quenching of hot suspension from 80 °C to room temperature resulted in the formation of AG-Co₃O₄ nanocomposite hydrogel. The as-synthesized AG-Co₃O₄ was characterized by FTIR, XRD and SEM techniques. In order to test the catalytic activity, AG-Co₃O₄ was used as a heterogeneous catalyst for the reduction of methylene blue (MB), congo red (CR) and 4-nitrophenol (4-NP). The excellent performance of the AG-Co₃O₄ was shown by the reaction rate constant (k_app) values of 0.3623, 0.2114 and 0.2893 for MB, 4-NP and CR, respectively. All these results were obtained with R² above 94 and utilization of an AG-Co₃O₄ catalyst. Furthermore, the catalytic reduction was studied with varying dye concentration and catalyst dose. This study showed that AG-Co₃O₄ catalyst has high potential for remediation of environmental pollutants in wastewaters.

Modified graphene supported Ag-Cu NPs with enhanced bimetallic synergistic effect in oxidation and Chan-Lam coupling reactions

Herein, well dispersed Ag–Cu NPs supported on modified graphene have been synthesized via a facile and rapid approach using sodium borohydride as a reducing agent under ambient conditions. Dicyandiamide is selected as an effective nitrogen source with TiO₂ as an inorganic material to form two kinds of supports, labelled as TiO₂–NGO and NTiO₂–GO. Initially, the surface area analysis of these two support materials was carried out which indicated that N-doping of GO followed by anchoring with TiO₂ has produced support material of larger surface area. Using both types of supports, ten nano-metal catalysts based on Ag and Cu were synthesized. Benefiting from the bimetallic synergistic effect and larger specific surface area of TiO₂–NGO, Cu@Ag–TiO₂–NGO is found to be a highly active and reusable catalyst out of other synthesized catalysts. It exhibits excellent catalytic activity for oxidation of alcohols and hydrocarbons as well as Chan–Lam coupling reactions. The nanocatalyst is intensively characterized by BET, SEM, HR-TEM, ICP-AES, EDX, CHN, FT-IR, TGA, XRD and XPS.

Cu@Ag–TiO₂–NGO prepared from modified graphene by simple methodology exhibits enhanced catalytic activity towards oxidation and Chan–Lam coupling due to the synergistic effect between Ag and Cu NPs.

Switching from Conventional to Nano-natural Phytochemicals to Prevent and Treat Cancers: Special Emphasis on Resveratrol

BACKGROUND

Natural phytochemicals and their derivatives have been used in medicine since prehistoric times. Natural phytochemicals have potential uses against various disorders, including cancers. However, due to low bioavailability, their success in clinical trials has not been reproduced. Nanotechnology has played a vital role in providing new directions for diagnosis, prevention, and treatment of different disorders, and of cancer in particular. Nanotechnology has demonstrated the capability to deliver conventional natural products with poor solubility or a short half-life to target specific sites in the body and regulate the release of drugs. Among the natural products, the phytoalexin resveratrol has demonstrated therapeutic effects, including antioxidant, antiinflammatory, and anti-proliferative effects, as well as the potential to inhibit the initiation and promotion of cancer. However, low water solubility and extensive first-pass metabolism lead to poor bioavailability of resveratrol, hindering its potential. Conventional dosage forms of resveratrol, such as tablets, capsules, dry powder, and injections, have met with limited success. Nanoformulations are now being investigated to improve the pharmacokinetic characteristics, as well as to enhance the bioavailability and targetability of resveratrol.

OBJECTIVES

This review details the therapeutic effectiveness, mode of action, and pharmacokinetic limitations of resveratrol, as well as discusses the successes and challenges of resveratrol nanoformulations. Modern nanotechnology techniques to enhance the encapsulation of resveratrol within nanoparticles and thereby enhance its therapeutic effects are emphasized.

CONCLUSION

To date, no resveratrol-based nanosystems are in clinical use, and this review would provide a new direction for further investigations on innovative nanodevices that could consolidate the anticancer potential of resveratrol.

Pollution, Toxicity and Carcinogenicity of Organic Dyes and their Catalytic Bio-Remediation

Water pollution due to waste effluents of the textile industry is seriously causing various health problems in humans. Water pollution with pathogenic bacteria, especially Escherichia coli (E. coli) and other microbes is due to the mixing of fecal material with drinking water, industrial and domestic sewage, pasture and agricultural runoff. Among the chemical pollutants, organic dyes due to toxic nature, are one of the major contaminants of industrial wastewater. Adequate sanitation services and drinking quality water would eliminate 200 million cases of diarrhea, which results in 2.1 million less deaths caused by diarrheal disease due to E. coli each year. Nanotechnology is an excellent platform as compared to conventional treatment methods of water treatment and remediation from microorganisms and organic dyes. In the current study, toxicity and carcinogenicity of the organic dyes have been studied as well as the remediation/inactivation of dyes and microorganism has been discussed. Remediation by biological, physical and chemical methods has been reviewed critically. A physical process like adsorption is cost-effective, but can't degrade dyes. Biological methods were considered to be ecofriendly and cost-effective. Microbiological degradation of dyes is cost-effective, eco-friendly and alternative to the chemical reduction. Besides, certain enzymes especially horseradish peroxidase are used as versatile catalysts in a number of industrial processes. Moreover, this document has been prepared by gathering recent research works related to the dyes and microbial pollution elimination from water sources by using heterogeneous photocatalysts, metal nanoparticles catalysts, metal oxides and enzymes.

Laser-assisted preparation of Pd nanoparticles on carbon cloth for the degradation of environmental pollutants in aqueous medium

Laser ablation in liquid (LAL), one of the attractive methods for fabrication of nanoparticles, was used for the modification of carbon cloth (CC) by deposition of palladium nanoparticles (Pd NPs); a simple stirring method was deployed to deposit Pd NPs on the CC surface. Characterization techniques viz X-ray diffraction (XRD), Fourier transform infrared (FT-IR), scanning electron microscope (SEM), energy-dispersive X-ray spectrometry (EDS) and inductively coupled plasma atomic emission spectroscopy (ICP-AES) were applied to study the surface of the ensuing samples which confirmed that LAL technique managed to fabricate and deposit the Pd NPs on the surface of CC. In addition, the catalytic prowess of the carbon cloth-Pd NPs (CC/Pd NPs) was investigated in the NaBH₄- or HCOOH-assisted reduction of assorted environmental pollutants in aqueous medium namely hexavalent chromium [Cr(VI)], 4-nitrophenol (4-NP), congo red (CR) and methylene blue (MB). The CC/Pd NPs system has advantages such as high stability/sustainability, high catalytic performance and easy reusability.