Natural cellulose fiber derived hollow-tubular-oriented polydopamine: In-situ formation of Ag nanoparticles for reduction of 4-nitrophenol

A review of cellulose-based catechol-containing functional materials for advanced applications

With the increment in global energy consumption and severe environmental pollution, it is urgently needed to explore green and sustainable materials. Inspired by nature, catechol groups in mussel adhesion proteins have been successively understood and utilized as novel biomimetic materials. In parallel, cellulose presents a wide class of functional materials rating from macro-scale to nano-scale components. The cross-over among both research fields alters the introduction of impressive materials with potential engineering properties, where catechol-containing materials supply a general stage for the functionalization of cellulose or cellulose derivatives. In this review, the role of catechol groups in the modification of cellulose and cellulose derivatives is discussed. A broad variety of advanced applications of cellulose-based catechol-containing materials, including adhesives, hydrogels, aerogels, membranes, textiles, pulp and papermaking, composites, are presented. Furthermore, some critical remaining challenges and opportunities are studied to mount the way toward the rational purpose and applications of cellulose-based catechol-containing materials.

Zn/Al layered double hydroxide and carboxymethyl cellulose composite beads as support for the catalytic gold nanoparticles and their applications in the reduction of nitroarenes

Until now, many efficient catalysts have been reported that are used for the reduction of nitroarenes. However, a catalyst reusability is a challenge that is often faced in practical environment. In this report, we designed a hydrogel composite (CMC-LDH), which act as support and making it possible to address this challenge. In this research work, zinc/aluminum based layered double hydroxides (Zn/Al LDH) have been assembled with carboxymethyl cellulose (CMC) to prepare CMC/LDH hydrogel beads. The CMC/LDH hydrogel beads were prepared by the ionotropic gelation method. For CMC/LDH/Au preparation, the already prepared CMC/LDH beads were kept in gold ion (Au3+) solution, and their subsequent reduction with sodium borohydride (NaBH4). For the characterization of the prepared samples different instrumental techniques, such as Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy, and scanning electron microscopy (SEM) were adopted. For the catalytic evaluation of CMC/LDH/Au, it was utilized as a catalyst in 4-NP and 4-NA reduction reactions. The continuity of the reaction was monitored by a UV-visible spectrophotometer. Rate constant (kapp) of 0.48474 min-1 and 0.7486 min-1 were obtained for 4-NP and 4-NA reduction, respectively. The hydrogel beads were recycled and reused for up to five successive cycles without significantly changing their catalytic efficiency.

Nano-sized and microporous palladium catalyst supported on modified chitosan/cigarette butt composite for treatment of environmental contaminants

This study reports a versatile process for the fabrication of a microporous heterogeneous palladium nanocatalyst on a novel spherical, biodegradable, and chemically/physically resistant catalyst support consisting of chitosan (CS) and cigarette waste-derived activated carbon (CAC). The physicochemical properties of the microporous Pd-CS-CAC nanocatalyst developed were successfully determined by FTIR, XRD, FE-SEM, TEM, BET, and EDS techniques. TEM studies showed that the average particle size of the synthesized Pd NPs was about 30 nm. The catalytic prowess of microporous Pd-CS-CAC was evaluated in the reduction/decolorization of various nitroarenes (2-nitroaniline (2-NA), 4-nitroaniline (4-NA), 4-nitrophenol (4-NP), and 4-nitro-o-phenylenediamine (4-NPD)) and organic dyes (methyl red (MR), methyl orange (MO), methylene blue (MB), congo red (CR), and rhodamine B (RhB)) in an aqueous medium in the presence of NaBH₄ as the reducing agent at room temperature. The catalytic activities were studied by UV-Vis absorption spectroscopy of the supernatant at regular time intervals. The short reaction times, mild reaction conditions, high efficiency (100% conversion), easy separation, and excellent chemical stability of the catalyst due to its heterogeneity and reusability are the advantages of this method. The results of the tests showed that reduction/decolorization reactions were successfully carried out within 10-140 s due to the good catalytic ability of Pd-CS-CAC. Moreover, Pd-CS-CAC was reused for 5 consecutive times with no loss of the initial shape, size, and morphology, confirming that it was a sustainable and robust nanocatalyst.

Efficient fabrication, antibacterial and catalytic performance of Ag-NiO loaded bacterial cellulose paper

This study reports the synthesis of bacterial cellulose (BC) hydrogel sheets and their utilization as a support for silver‑nickel oxide nanocomposites (Ag/NiO). A two-step facile hydrothermal method was employed for the preparation of Ag/NiO, followed by impregnation into BC hydrogel sheets. A 20% Ag/NiO composition was revealed by dry weight analysis. The stability of nanocomposites-Hydrogel was confirmed by Ag⁺ and Ni²⁺ ion release study. The catalytic activity of the BC-Ag/NiO was evaluated against chemical reduction of congo red, methyl orange and methylene blue. The reduction reaction followed pseudo first order kinetics and k_app values of 0.1147 min^-1, 0.1323 min^-1 and 0.12989 min^-1 were obtained for CR, MO, and MB dyes, respectively. The BC-Ag/NiO catalyst could be easily recovered and re-used in another reaction without centrifugation. The synthesized nanocomposites hydrogel was also tested for its antibacterial activity against Gram-negative bacteria, Escherichia coli (E.coli) and Gram-positive bacteria, Staphylococcus aureus (S.aureus).

Ag/LDH-itaconic acid-gellan gam nanocomposites: Facile and green synthesis, characterization, and excellent catalytic reduction of 4-nitrophenol

The catalytic reduction reaction is one of the most commonly used solutions to convert high-risk contaminants into safe or low-risk materials. Today, with the increasing water pollution, the urgent need for efficient and effective catalysts is felt more than ever. For this purpose, for the first time, a green catalyst composed of silver nanoparticles anchored on itaconic acid-modified Ca-Al layered double hydroxide/gellan gum nanocomposite (Ag/LDH-ITA-GG NC) was prepared from a green approach without the use of any toxic organic solvents. To gain an in-depth insight into the physicochemical properties of the catalyst, different techniques including nitrogen adsorption-desorption isotherms, FESEM/mapping, FTIR, TGA, and XRD were used. The catalytic performance of the Ag/LDH-ITA-GG NC toward 4-nitrophenol reduction by NaBH₄ was investigated. The calculated values of the apparent rate constant for this reaction are 0.2142 min^-1 (for 1.0 mg of the catalyst), 0.2375 min^-1 (for 3.0 mg of the catalyst), and 0.2550 min^-1 (for 5.0 mg of the catalyst), indicating that the catalytic conversion of 4-nitrophenol to 4-aminophenol on the Ag/LDH-ITA-GG NC catalyst follows the pseudo-first-order kinetics and is comparable to the previous findings in the literature. The results of this study indicated that Ag/LDH-ITA-GG NC can potentially be utilized as an auspicious high efficient green catalyst for the reduction of pollutants like 4-nitrophenol.

A Review on Silver Nanoparticles: Classification, Various Methods of Synthesis, and Their Potential Roles in Biomedical Applications and Water Treatment

Recent developments in nanoscience have appreciably modified how diseases are prevented, diagnosed, and treated. Metal nanoparticles, specifically silver nanoparticles (AgNPs), are widely used in bioscience. From time to time, various synthetic methods for the synthesis of AgNPs are reported, i.e., physical, chemical, and photochemical ones. However, among these, most are expensive and not eco-friendly. The physicochemical parameters such as temperature, use of a dispersing agent, surfactant, and others greatly influence the quality and quantity of the synthesized NPs and ultimately affect the material’s properties. Scientists worldwide are trying to synthesize NPs and are devising methods that are easy to apply, eco-friendly, and economical. Among such strategies is the biogenic method, where plants are used as the source of reducing and capping agents. In this review, we intend to debate different strategies of AgNP synthesis. Although, different preparation strategies are in use to synthesize AgNPs such as electron irradiation, optical device ablation, chemical reduction, organic procedures, and photochemical methods. However, biogenic processes are preferably used, as they are environment-friendly and economical. The review covers a comprehensive discussion on the biological activities of AgNPs, such as antimicrobial, anticancer anti-inflammatory, and anti-angiogenic potentials of AgNPs. The use of AgNPs in water treatment and disinfection has also been discussed in detail.

Enhanced Conductivity and Antibacterial Behavior of Cotton via the Electroless Deposition of Silver

In this study, the surface-initiated atom transfer radical polymerization (SI-ATRP) technique and electroless deposition of silver (Ag) were used to prepare a novel multi-functional cotton (Cotton-Ag), possessing both conductive and antibacterial behaviors. It was found that the optimal electroless deposition time was 20 min for a weight gain of 40.4%. The physical and chemical properties of Cotton-Ag were investigated. It was found that Cotton-Ag was conductive and showed much lower electrical resistance, compared to the pristine cotton. The antibacterial properties of Cotton-Ag were also explored, and high antibacterial activity against both Escherichia coli and Staphylococcus aureus was observed.

A redox interaction-engaged strategy for multicomponent nanomaterials

The review article focuses on the redox interaction-engaged strategy that offers a powerful way to construct multicomponent nanomaterials with precisely-controlled size, shape, composition and hybridization of nanostructures.

Preparation of Magnetic CuFe2O4@Ag@ZIF-8 Nanocomposites with Highly Catalytic Activity Based on Cellulose Nanocrystals

A facile approach was successfully developed for synthesis of cellulose nanocrystals (CNC)-supported magnetic CuFe2O4@Ag@ZIF-8 nanospheres which consist of a paramagnetic CuFe2O4@Ag core and porous ZIF-8 shell. The CuFe2O4 nanoparticles (NPs) were first prepared in the presence of CNC and dispersant. Ag NPs were then deposited on the CuFe2O4/CNC composites via an in situ reduction directed by dopamine polymerization (PDA). The CuFe2O4/CNC@Ag@ZIF-8 nanocomposite was characterized by TEM, FTIR, XRD, N2 adsorption-desorption isotherms, VSM, and XPS. Catalytic studies showed that the CuFe2O4/CNC@Ag@ZIF-8 catalyst had much higher catalytic activity than CuFe2O4@Ag catalyst with the rate constant of 0.64 min-1. Because of the integration of ZIF-8 with CuFe2O4/CNC@Ag that combines the advantaged of each component, the nanocomposites were demonstrated to have an enhanced catalytic activity in heterogeneous catalysis. Therefore, these results demonstrate a new method for the fabrication of CNC-supported magnetic core-shell catalysts, which display great potential for application in biocatalysis and environmental chemistry.

Fabrication of tubular braid reinforced PMIA nanofiber membrane with mussel-inspired Ag nanoparticles and its superior performance for the reduction of 4-nitrophenol

A novel tubular braid reinforced (TBR) PMIA/CA-PEI/Ag nanofiber membrane for application in dynamic catalysis was introduced in this study. The preparation method of the TBR PMIA/CA-PEI/Ag nanofiber membrane was facile and efficient. The TBR PMIA/CA-PEI/Ag nanofiber membrane was characterized by field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and thermal gravimetric analysis (TGA). The mechanical properties were evaluated by a universal material testing machine. The tensile strength of TBR nanofiber membrane exceeded 500 MPa, whereas that of the nanofiber membrane without reinforcement was merely 10 MPa. Besides, the compressive strength of the TBR nanofiber membrane was also reinforced, which indicated that the TBR nanofiber membrane could withstand a higher operating pressure. The reduction of 4-NP to 4-AP was selected as the model reaction to evaluate the catalytic property of TBR PMIA/CA-PEI/Ag nanofiber membrane. The apparent rate constant of dynamic catalysis was 34.58 times higher than that of static catalysis. After 10 cycles, the conversion of 4-NP was still higher than 95.3%. This indicated that the TBR PMIA/CA-PEI/Ag nanofiber membrane had superior stability and recyclability. Besides, the TBR PMIA/CA-PEI/Ag nanofiber membrane also showed superior catalytic performance when it was used for catalyzing other environmental pollutants.

Removal of methyl orange dye and copper (II) ions from aqueous solution using polyaniline-coated kapok (Ceiba pentandra) fibers

Hollow tubular structured kapok fibers (Ceiba pentandra) were coated with polyaniline (PANI) molecules using an in situ oxidative polymerization technique. The tubular morphology of the kapok fibers was retained after PANI coating. The Fourier transform infrared (FT-IR) spectrum of the PANI-coated kapok fibers illustrated the vibration modes associated with the presence of PANI molecules. The PANI-treated kapok fibers achieved complete wettability with water molecules (zero water contact angle) from initially being highly hydrophobic (contact angle = 120°). In the present work, the removal of contaminants such as methyl orange dye and Cu(II) from aqueous solution using polyaniline-coated kapok fibers was investigated. Isotherm studies show that the removal of methyl orange dye (R² ≥ 0.959) and Cu(II) (R² ≥ 0.972) using PANI-coated kapok fibers follow the Langmuir isotherm model with maximum sorption capacities determined to be 75.76 and 81.04 mg/g, respectively. Based from thermodynamic studies, the sorption of methyl orange dye and Cu(II) are endothermic, feasible and spontaneous. Furthermore, kinetic studies show that the both processes follow a pseudo-second-order model, implying that the rate-determining step is chemisorption.

Preparation of Hierarchical Porous Silicalite-1 Encapsulated Ag NPs and Its Catalytic Performance for 4-Nitrophenol Reduction

A facile and efficient strategy is presented for the encapsulation of Ag NPs within hierarchical porous silicalite-1. The physicochemical properties of the resultant catalyst are characterized by TEM, XRD, FTIR, and N₂ adsorption-desorption analytical techniques. It turns out that the Ag NPs are well distributed in MFI zeolite framework, which possesses hierarchical porous characteristics (1.75, 3.96 nm), and the specific surface area is as high as 243 m² · g^-1. More importantly, such catalyst can rapidly transform the 4-nitrophenol to 4-aminophenol in aqueous solution at room temperature, and a quantitative conversion is also obtained after being reused 10 times. The reasons can be attributed to the fast mass transfer, large surface area, and spatial confinement effect of the advanced support.

Sonochemical green reduction to prepare Ag nanoparticles decorated graphene sheets for catalytic performance and antibacterial application

The emerging popularity and wide acceptance of green chemistry and environmentally benign/ecofriendly approaches have comprehensively considered for catalyst synthesis methods. Natural resource derived carbogenic quantum dots has been used in assistance with ultrasonic shock wave to graphene oxide (GO) aqueous dispersion in order to prepare reduced graphene oxide decorated with silver nanoparticles following the 'top-down' method. The total reduction process is done without using any toxic external reducing agents and any surfactants or stabilizers, thus it can be accepted as green method. Sonochemical destratification of the GO layers provides green attributes due to scalable, non-hazardous and relatively fast reduction to enhance surface area of the GO. Arresting the silver nanoparticles onto basal planes of graphene oxide can act as an efficient solid state support catalyst for fast reduction of toxic nitro aryls. Besides this work also reports bactericidal feature exhibited by the catalyst. Thus a dual functioning nanomaterial has been successfully developed which can be a suitable alternative for reductive forthcoming specialty/multifunctional membrane and other high-end medicinal or industrial applications.

The role of cellulose nanocrystals incorporation route in waterborne polyurethane for preparation of electrospun nanocomposites mats

Electrospinning offers the possibility of obtaining fibers mats from polymer solutions. The use of environmentally-friendly waterborne polyurethane (WBPU) allows obtaining electrospun polyurethane mats in water medium. Furthermore, the incorporation of water dispersible nanoentities, like renewable cellulose nanocrystals (CNC), is facilitated. Therefore, in this work, a WBPU was synthesized and CNC were isolated for preparing WBPU-CNC dispersions nanocomposites with 1 and 3wt% of CNC following both the classical mixing by sonication, and the innovative in-situ route. The dispersions were used for obtaining electrospun mats assisted by poly(ethylene oxide) (PEO) as polymer template. Moreover, the extraction of PEO with water resulted in continuous WBPU-CNC mats, showing different properties respect to WBPU-CNC mats containing PEO. The effective addition of CNC led to more defined cylindrical morphologies and the two alternative incorporation routes induced to different CNC dispositions in the matrix, which modified fibers diameters, and thus, mats final properties.