Metal nanoparticles decorated mint-cellulose acetate composite as an efficient catalyst for the reduction of methyl orange.

Water contamination caused by toxic compounds has emerged as one of the most severe challenges worldwide. Biomass-based nanocomposites offer a sustainable and renewable alternative to conventional materials. In this study, a nanocomposite of mint and cellulose acetate (Mint-CA) was prepared and employed as a supportive material for Cu nanoparticles (CuNPs) and Ag nanoparticles (AgNPs). The selectivity of CuNPs@mint-CA and AgNPs@mint-CA was assessed by comparing their performance in the reduction reaction of various dyes solutions. AgNPs@mint-CA exhibited superior catalytic performance, with a removal of 95.2 % for methyl orange (MO) compared to 68 % with CuNPs@mint-CA. The absorption spectra of MO exhibited a distinct peak at 464 nm. The reduction reaction of MO by AgNPs@mint-CA followed pseudo-first-order-kinetic with a rate constant of k = 0.0063 min-1 (R2 = 0.928). The highest removal of MO was achieved under the following conditions: a catalyst weight of 40 mg, an initial MO concentration of 0.07 mM, the addition of 0.5 mL of 0.1 M NaBH4, and a temperature of 25 °C. Furthermore, the AgNPs@mint-CA catalyst exhibited exceptional reducibility even after five use cycles, highlighting its potential for efficiently removing MO.

Silver oxide doped iron oxide/alginate nanocomposite coated cotton cloth for selective catalytic reduction of potassium ferricyanide.

Silver oxide doped iron oxide (Ag2O-Fe2O3) nanocatalyst was prepared and coated on cotton cloth (CC) as well as wrapped in sodium alginate (Alg) hydrogel. Ag2O-Fe2O3 coated CC (Ag2O-Fe2O3/CC) and Ag2O-Fe2O3 wrapped Alg (Ag2O-Fe2O3/Alg) were utilized as catalysts in reduction reaction of 4-nitrophenol (4-NP), congo red (CR), methylene blue (MB) and potassium ferricyanide (K3[Fe(CN)6]). Ag2O-Fe2O3/CC and Ag2O-Fe2O3/Alg were found to be effective and selective catalyst for the reaction of K3[Fe(CN)6]. Further amount of catalyst, K3[Fe(CN)6] quantity, amount of NaBH4, stability of catalyst and recyclability were optimized for the reaction of K3[Fe(CN)6] reduction. Ag2O-Fe2O3/Alg and Ag2O-Fe2O3/CC were appeared to be the stable catalysts by maintaining high activity during recyclability tests showing highest reaction rate constants (kapp) of 0.3472 and 0.5629 min-1, correspondingly. However, Ag2O-Fe2O3/CC can be easily recovered as compared to Ag2O-Fe2O3/Alg by simply removing from the reaction which is the main advantage of Ag2O-Fe2O3/CC. Moreover, Ag2O-Fe2O3/Alg and Ag2O-Fe2O3/CC were also examined in real samples and found useful for K3[Fe(CN)6] reduction involving real samples. The Ag2O-Fe2O3/CC nanocatalyst is a cost and time saving material for economical reduction of K3[Fe(CN)6] and environmental safety.

SnLa2O5 wrapped carboxymethyl cellulose mixed calcium alginate nanocomposite beads for efficient reduction of pollutants.

In this project, lanthanum oxide doped tin oxide (SnLa2O5) nanomaterial was prepared and characterized morphologically and physiochemically by different techniques. The catalytic performance of SnLa2O5 was assessed toward catalytic reduction of 4-nitrophenol (4-NP), methyl orange (MO), congo red (CR), methylene blue (MB) and potassium ferricyanide (K3[Fe(CN)6]). SnLa2O5 was found to be efficient for K3[Fe(CN)6] in the presence of NaBH4, which reduced in only 8.0 min. SnLa2O5 was further wrapped in carboxymethyl cellulose mixed calcium alginate (CMC-Alg) hydrogel beads because the powder catalyst cannot be simply recovered from reaction media to recycle and use again. SnLa2O5 wrapped CMC-Alg (SnLa2O5/CMC-Alg) was assessed for detail analysis of K3[Fe(CN)6] reduction. The effect of NaBH4, K3[Fe(CN)6] concentration and amount of catalyst was optimized using SnLa2O5/CMC-Alg. The amount of catalyst has positive impact on catalytic reduction of K3[Fe(CN)6]. The kinetic study revealed that K3[Fe(CN)6] reduction by SnLa2O5 and SnLa2O5/CMC-Alg was fast, which completed in 8.0 and 4.0 min with rate constant of 0.4283 min-1 and 0.7461 min-1, respectively. These findings indicated that the developed SnLa2O5/CMC-Alg is best and proficient nanocatalyst for K3[Fe(CN)6] reduction. The efficiency along with cost-effective and simple treatment route of the developed nanocatalyst have prospect to compete and replace the reputable commercial catalysts.

Carboxymethyl Cellulose/Copper Oxide-Titanium Oxide Based Nanocatalyst Beads for the Reduction of Organic and Inorganic Pollutants.

In this work, we have developed novel beads based on carboxymethyl cellulose (CMC) encapsulated copper oxide-titanium oxide (CuO-TiO2) nanocomposite (CMC/CuO-TiO2) via Al+3 cross-linking agent. The developed CMC/CuO-TiO2 beads were applied as a promising catalyst for the catalytic reduction of organic and inorganic contaminants; nitrophenols (NP), methyl orange (MO), eosin yellow (EY) and potassium hexacyanoferrate (K3[Fe(CN)6]) in the presence of reducing agent (NaBH4). CMC/CuO-TiO2 nanocatalyst beads exhibited excellent catalytic activity in the reduction of all selected pollutants (4-NP, 2-NP, 2,6-DNP, MO, EY and K3[Fe(CN)6]). Further, the catalytic activity of beads was optimized toward 4-nitrophenol with varying its concentrations and testing different concentrations of NaBH4. Beads stability, reusability, and loss in catalytic activity were investigated using the recyclability method, in which the CMC/CuO-TiO2 nanocomposite beads were tested several times for the reduction of 4-NP. As a result, the designed CMC/CuO-TiO2 nanocomposite beads are strong, stable, and their catalytic activity has been proven.

SnAg2O3-Coated Adhesive Tape as a Recyclable Catalyst for Efficient Reduction of Methyl Orange.

Silver oxide-doped tin oxide (SnAg2O3) nanoparticles were synthesized and different spectroscopic techniques were used to structurally identify SnAg2O3 nanoparticles. The reduction of 4-nitrophenol (4-NP), congo red (CR), methylene blue (MB), and methyl orange (MO) was studied using SnAg2O3 as a catalyst. Only 1.0 min was required to reduce 95% MO; thus, SnAg2O3 was found to be effective with a rate constant of 3.0412 min-1. Being a powder, SnAg2O3 is difficult to recover and recycle multiple times. For this reason, SnAg2O3 was coated on adhesive tape (AT) to make it recyclable for large-scale usage. SnAg2O3@AT catalyst was assessed toward MO reduction under various conditions. The amount of SnAg2O3@AT, NaBH4, and MO was optimized for best possible reduction conditions. The catalyst had a positive effect since it speed up the reduction of MO by adding more SnAg2O3@AT and NaBH4 as well as lowering the MO concentration. SnAg2O3@AT totally reduced MO (98%) in 3.0 min with a rate constant of 1.3669 min-1. These findings confirmed that SnAg2O3@AT is an effective and useful catalyst for MO reduction that can even be utilized on a large scale for industrial purposes.

Adsorptive removal of heavy metals and organic dyes by sodium alginate/coffee waste composite hydrogel.

Heavy metals and dyes used in technological applications have a detrimental influence on human health and the environment. The most used methods for removing pollutants depend on high-cost materials. Therefore, this research was conducted on cost-effective alternatives derived from natural resources and food waste. Herein, we designed a composite hydrogel based on sodium alginate/coffee waste (Alg/coffee) as adsorbent for the removal of organic and inorganic pollutants from aquatic solutions. The selectivity study displayed that Alg/coffee is more effective in adsorbing Pb(II) and acridine orange dye (AO). Adsorption of Pb(II) and AO was studied at concentration range of 0-170 mgL-1 and 0-40 mgL-1. Adsorption data of Pb(II) and AO reveals their fitting to Langmuir-isotherm and pseudo-second-order-kinetic models. The findings demonstrated that Alg/coffee hydrogel are more effective than coffee powder itself with an adsorption (%) approaching 98.44 % of Pb(II) and 80.53 % of AO. Real sample analysis reveals the efficiency of Alg/coffee hydrogel beads in Pb(II) adsorption. The adsorption cycle was examined four times providing high efficiency toward Pb(II) and AO. Desorption of Pb(II) and AO was easily performed using HCl eluent. Thus, Alg/coffee hydrogel beads could be promising adsorbent for the removal of organic and inorganic pollutants.

Lignin nanoparticles-reduced graphene oxide based hydrogel: A novel strategy for environmental applications.

In this work, facile fabrication of lignin nanoparticles (LNP)-based three-dimensional reduced graphene oxide hydrogel (rGO@LNP) has been demonstrated as a novel strategy for environmental applications. Herein, LNP were facilely synthesized from walnut shell waste through a direct chemical route. These LNP were incorporated into the continuous porous network of rGO network to fabricate rGO@LNP hydrogel. Characterization studies were carried out using various analytical techniques viz. scanning electron microscopy, Fourier transform IR spectroscopy, X-ray diffraction and thermogravimetric analysis. The efficiency of rGO@LNP hydrogel as adsorptive platform was evaluated by employing methylene blue and Pb2+ as model pollutants, whilst the effect of various experimental parameters was ascertained for optimal performance. Furthermore, Agar well diffusion method was used to check the antibacterial activities of the hydrogel using two bacterial pathogenic strains, i.e. Klebsiella pneumoniae (gram negative) and Enterococcus faecalis (gram positive). Results showed that after the inclusion of LNP into rGO hydrogel, there was a marked improvement in pollutant's uptake ability and compared to bare LNP and rGO, the composite hydrogel showed enhanced bactericidal effect. Overall, this approach is outstanding because of the synergy of functional properties of nano-lignin and rGO due to multi-interaction sites in the resulting hydrogel. The results presented herein support the application of rGO@LNP as innovative water filter material for scavenging broad spectrum pollutants and bactericidal properties.

Chitosan hydrogel anchored phthalocyanine supported metal nanoparticles: Bifunctional catalysts for pollutants reduction and hydrogen production.

Metal nanoparticles possess high catalytic activity in various organic transformation reactions. A catalyst must be recovered and re-used effectively and economically to lower the overall reaction cost. The recovery of a catalyst remains a challenge due to their extreme small size. In this research work, catalytic metal nanoparticles were synthesized on Zn-phthalocyanine (ZnPc) and chitosan hydrogel (CH) composite which acts as catalyst support. The ZnPc-CH support facilitate the easy recovery of the loaded metal nanoparticles. Metal nanoparticles (M0) based on Cu0, Ag0, Ni0, Co0 and Fe0 were decorated inside and on ZnPc-CH hydrogel surface. The developed M0@ZnPc-CH were utilized for the enhanced selective reduction of toxins and hydrogen production by methanolysis and hydrolysis of NaBH4. Effective catalytic reduction and hydrogen generation was successfully achieved with Co0@ZnPc-CH and ZnPc-CH. Under optimized conditions, Co0@ZnPc-CH showed complete reduction of 4-nitrophenol (4-NP) in 8.0 min with the fast 4-NP reduction kinetics (K = 0.611 min-1). Among the developed catalysts, ZnPc-CH showed fast H2 generation with high H2 generation rate (HGR = 4100 mLg-1min-1) under optimized conditions. Metal leaching from Co0@ZnPc-CH was negligible during recycling of the catalyst, suggesting that it could be implemented to 4-NP treatment from real water samples. Similarly, ZnPc-CH could produce same quantity of H2 throughout 4 continuous cycles of durability testing without any deactivation and leaching and ZnPc-CH showed high stability, indicating the effectiveness of the catalyst to be applied for H2 production on large scale.

Novel Synthesis of CuO/GO Nanocomposites and Their Photocatalytic Potential in the Degradation of Hazardous Industrial Effluents.

Photocatalytic degradation of dyes has been the subject of extensive study due to its low cost, eco-friendly operation, and absence of secondary pollutants. Copper oxide/graphene oxide (CuO/GO) nanocomposites are emerging as a new class of fascinating materials due to their low cost, nontoxicity, and distinctive properties such as a narrow band gap and good sunlight absorbency. In this study, copper oxide (CuO), graphene oxide (GO), and CuO/GO were synthesized successfully. X-ray diffractometer (XRD) and Fourier transform infrared (FTIR) spectroscopy confirm the oxidation and production of GO from the graphene of lead pencil. According to the morphological analysis of nanocomposites, CuO nanoparticles of sizes ≤20 nm on the GO sheets were evenly adorned and distributed. Nanocomposites of different CuO:GO ratios (1:1 up to 5:1) were applied for the photocatalytic degradation of methyl red (MR). CuO:GO(1:1) nanocomposites achieved 84% MR dye removal, while CuO:GO(5:1) nanocomposites achieved the highest value (95.48%). The thermodynamic parameters of the reaction for CuO:GO(5:1) were evaluated using the Van't Hoff equation and the activation energy was found to be 44.186 kJ/mol. The reusability test of the nanocomposites showed high stability even after seven cycles. CuO/GO catalysts can be used in the photodegradation of organic pollutants in wastewater at room temperature due to their excellent properties, simple synthesis process, and low cost.

Substantial increase in adsorption efficiency of local clay-alginate beads toward methylene blue impregnated with SDS.

In the current research work, local clay-alginate beads loaded with sodium dodecyl sulfate (SDS) surfactant were prepared for efficient adsorption of methylene blue (MB). FTIR, SEM-EDX, and TGA instruments were used to examine the surface functional groups, morphology, elemental analysis, and thermal stability of beads, respectively. The adsorption efficiency of native clay for MB increases from 124.78 to 247.94 mg/g when loaded in alginate and SDS in beads form. The impacts of adsorbent dosage, initial pH, contact time, initial MB concentration, and temperature were investigated and optimized. The maximum adsorption capacity of beads for MB was 1468.5 mg/g. The process followed a pseudosecond order kinetic and Freundlich adsorption isotherm model. Thermodynamic study confirmed that MB adsorption on beads is endothermic and spontaneous in nature. The beads were recycled and reused for five times. According to the findings, local clay-alginate beads impregnated with SDS proved to be a promising and efficient adsorbent for extracting MB from aqueous solution.

Emerging Fabrication Strategies of Hydrogels and Its Applications.

Recently, hydrogels have been investigated for the controlled release of bioactive molecules, such as for living cell encapsulation and matrices. Due to their remote controllability and quick response, hydrogels are widely used for various applications, including drug delivery. The rate and extent to which the drugs reach their targets are highly dependent on the carriers used in drug delivery systems; therefore the demand for biodegradable and intelligent carriers is progressively increasing. The biodegradable nature of hydrogel has created much interest for its use in drug delivery systems. The first part of this review focuses on emerging fabrication strategies of hydrogel, including physical and chemical cross-linking, as well as radiation cross-linking. The second part describes the applications of hydrogels in various fields, including drug delivery systems. In the end, an overview of the application of hydrogels prepared from several natural polymers in drug delivery is presented.

Effect of Humidity and Temperature on the Impedances and Voltage of Al/Gr-Jelly/Cu-Rubber Composite-Based Flexible Electrochemical Sensors.

Here we present the fabrication of graphene and jelly (superabsorbent polymer) electrolyte composite-based shockproof flexible electrochemical sensors (Al/Gr-Jelly/Cu) and their properties under the effect of humidity and temperature. A layer of graphene mixed in jelly electrolyte was drop-casted onto porous rubber substrates between preliminary fixed aluminum (Al) and copper (Cu) electrodes followed by rubbing-in. It was observed that the graphene and jelly mixture was mechanically soft and flexible, similar to jelly. Electrically, this mixture (graphene and jelly) behaved as a flexible electrolyte. It was observed that under the effect of humidity ranging from 47 to 98%, the impedances of the sensors decreased by 2.0 times on average. Under the effect of temperatures ranging from 21 to 41 °C the impedances decreased by 2.4 times. The average temperature coefficient of impedances was equal to -0.03 °C-1. The electrochemical voltage generated by the flexible jelly electrolyte sensors was also investigated. It was found that the initial open-circuit voltages were equal to 201 mV and increased slightly, by 5-10% under the effect of humidity and temperature as well. The short-circuit currents under the effect of humidity and temperature increased by 2-3 times. The Al/Gr-Jelly/Cu electrochemical sensors may be used as prototypes for the development of the jelly electronic-based devices.

Preparation, Characterization, and Biological Features of Cactus Coated Bacterial Cellulose Hydrogels.

The current study was aimed at developing BC-Cactus (BCC) composite hydrogels with impressive mechanical features for their potential applications in medical and environmental sectors. BCC composites hydrogels were developed through cactus gel coating on a never dried BC matrix. The FE-SEM micrographs confirmed the saturation of BC fibrils with cactus gel. Additionally, the presence of various functional groups and alteration in crystalline behavior was confirmed through FTIR and XRD analysis. Mechanical testing illustrated a three-times increase in the strain failure and an increase of 1.6 times in the tensile strength of BCC composite. Absorption capabilities of BCC were much higher than pure BC and it retained water for a longer period of time. Additionally, the rewetting and absorption potentials of composites were also higher than pure BC. The composite efficiently adsorbed Pb, Zn, Cu, and Co metals. Biocompatibility studies against human HaCat cell line indicated much better cell adhesion and proliferation of BCC compared to BC. These findings advocate that the BCC composite could find applications in medical, pharmaceutical and environmental fields.

Copper Oxide-Antimony Oxide Entrapped Alginate Hydrogel as Efficient Catalyst for Selective Reduction of 2-Nitrophenol.

Copper oxide-antimony oxide (Cu2O-Sb2O3) was prepared and entrapped inside Na-alginate hydrogel (Alg@Cu2O-Sb2O3). The developed Alg@Cu2O-Sb2O3 was used as catalytic reactor for the reduction of 4-nitrophenol (4-NP), 2-nitrophenol (2-NP), 2,6-dinitrophenol (2,6-DNP), methyl orange (MO), congo red (CR), acridine orange (AO), methylene blue (MB) and potassium ferricyanide (K3[Fe(CN)6]). Alg@Cu2O-Sb2O3 was found to be selective and more efficient for the reduction of 2-NP among all the pollutants. Therefore, 2-NP was selected for a detailed study to optimize various parameters, e.g., the catalyst amount, reducing agent concentration, 2-NP concentration and recyclability. Alg@Cu2O-Sb2O3 was found to be very stable and easily recyclable for the reduction of 2-NP. The Alg@Cu2O-Sb2O3 nanocatalyst reduced 2-NP in 1.0 min, having a rate constant of 3.8187 min-1.

Alginate biopolymer as a reactor container for copper oxide-tin oxide: Efficient nanocatalyst for reduction of different pollutants.

The need of clean water demands to design an efficient catalytic system with high effective and selective reduction of water pollutants. Here, we successfully prepared copper oxide-tin oxide (CuO-SnO2) nanomaterial and further wrapped in Na-alginate hydrogel (Alg/CuO-SnO2). CuO-SnO2 and Alg/CuO-SnO2 were characterized by FESEM, EDS, FTIR-ATR, and XRD and tested for the reduction of water pollutants. The catalytic ability of CuO-SnO2 and Alg/CuO-SnO2 was examined for numerous pollutants like 4-nitrophenol (4-NP), methyl orange (MO), congo red (CR), methylene blue (MB) and potassium ferricyanide (K3[Fe(CN)6]) where the designed CuO-SnO2 and Alg/CuO-SnO2 nanocatalysts were most selective toward MB reduction. Further on optimization of catalyst amount, stability, and reducing agent amount, it was found that the increase of nanocatalyst amount and NaBH4 concentration increase the rate of MB reduction. CuO-SnO2 and Alg/CuO-SnO2 nanocatalysts reduced MB in 3.0 min with reaction rate constants (kapp) of 1.2944 min-1 and 1.2715 min-1, respectively. Additionally, Alg/CuO-SnO2 nanocatalyst was easily recovered by simply pulling hydrogel after completion of reaction and reused four times with no loss in efficiency. Besides, Alg/CuO-SnO2 nanocatalyst was further investigated in real samples like sea water, irrigation water, well water, university wastewater and found effective for MB reduction even in real samples.

Metal nanoparticles supported chitosan coated carboxymethyl cellulose beads as a catalyst for the selective removal of 4-nitrophenol.

In the area of water pollution treatment, the coupling of biopolymers with metal/metal nanoparticles is getting a lot of interest these days. Herein, carboxymethyl cellulose (CMC) beads and chitosan (Cs) coated CMC beads were employed as a support for copper nanoparticles, (Cu/CMC) and (Cu/Cs@CMC), respectively. Following that, a reducing agent (NaBH4) was used to convert Cu/CMC and Cu/Cs@CMC beads to zero valent. The developed beads were employed for catalytic reductions of nitrophenol, dyes, and potassium hexacyanoferrate (III) in their mixed solution with NaBH4. Cu/Cs@CMC beads were more efficient compared to Cu/CMC beads toward selected pollutants. The reduction rate constants of 4-NP, MO, EY and K3[Fe(CN)6] by utilizing Cu/Cs@CMC were 3.8 × 10-1, 4.0 × 10-1, 1.4 × 10-1 and 4.48 × 10-1 min-1, respectively. Further, the catalytic activity of the Cu/Cs@CMC beads were optimized using 4-NP as a model compound for this study. Cu/Cs@CMC beads were able to use up to three cycles compared to Cu/CMC beads without losing catalytic activity in the reduction of 4-NP, according to the recyclability and reusability study of both beads. The chitosan coating beads Cu/Cs@CMC was simply prepared and have good catalytic activity, recyclable, and more efficient than Cu/CMC beads due to their high strength and stability.

Nanoarchitectured Cu based catalysts supported on alginate/glycyl leucine hybrid beads for tainted water treatment.

Water pollution reached worrying point due to different dye pollutants which demands an instant solution. One of the best ways to manage water pollutants is their reduction and decolorization to less-toxic and useful compounds. However, reduction process requires an effective, stable, and recyclable catalyst to reduce such pollutants more effectively. Metal nanoparticles (M0) are highly effective catalysts but separation of nanoparticles after reaction is difficult and requires a high-speed centrifugation. If loaded on polymer-beads, they can be easily separated from the reaction-mixture. Hearin, alginate/glycyl leucine (AGL) hybrid-beads were prepared, and copper nanoparticles (Cu0) were grown on it by simple process. M0/AGL bead catalysts were tested toward reducing various toxic compounds. Among all developed composite-beads, the catalytic performance of Cu0/AGL was highest in terms of reduction kinetics. After initial screening for different pollutants, Cu0/AGL was much more effective for MO reduction, thus, all optimized different parameters i.e., catalyst dosage, stability, amount of reducing-agent and recyclability were experimentally determined. The Cu0/AGL showed high-rate constants (kapp) of 0.7566 and 2.9506 min-1 depending on beads content. The reusability of the Cu0/AGL catalysts up to the 7th cycle has been checked. With the use of AGL as support for the Cu nanoparticles, not only the catalytic activity was retained for longer times during reusability, but it helped in their easy separation.

Ultraviolet and Infrared Irradiations Sensing of Gel-Orange Dye Composite-Based Flexible Electrochemical Cells.

The flexible and shockproof rubber-based Al/OD-Gel/Cu electrochemical cell was designed, fabricated, and investigated for the detection of IR and UV irradiations. For this purpose, the transparent gel-orange dye composite was deposited on the porous rubber substrate between aluminum and copper electrodes. It was observed that the gel-orange dye composite was mechanically like a gel: soft and flexible. Electrically, this composite (gel-orange dye) forms a flexible electrolyte. It was found that the impedance of the samples under the effect of infrared irradiation decreased by 2.02 to 2.19 times on changing frequency from 100 Hz to 200 kHz. Accordingly, under the effect of ultraviolet irradiation, the impedance of the samples decreased by 1.23 to 1.45 times on increasing frequency from 100 Hz to 200 kHz. Under the effect of infrared irradiation up to 4000 W/m2, the cell's open-circuit voltage increased by 1.59 times. The cell's open-circuit voltage also increased by 1.06 times under the effect of ultraviolet irradiation up to 200 uW/cm2. The mechanism of the absorption of the infrared and ultraviolet irradiations by the OD-Gel composite has been discussed in detail. The fabricated flexible rubber substrate-based Al/OD-Gel/Cu electrochemical cells can be used as a prototype for the development of gel electronics-based devices.

Chitosan@Carboxymethylcellulose/CuO-Co2O3 Nanoadsorbent as a Super Catalyst for the Removal of Water Pollutants.

In this work, an efficient nanocatalyst was developed based on nanoadsorbent beads. Herein, carboxymethyl cellulose-copper oxide-cobalt oxide nanocomposite beads (CMC/CuO-Co2O3) crosslinked by using AlCl3 were successfully prepared. The beads were then coated with chitosan (Cs), Cs@CMC/CuO-Co2O3. The prepared beads, CMC/CuO-Co2O3 and Cs@CMC/CuO-Co2O3, were utilized as adsorbents for heavy metal ions (Ni, Fe, Ag and Zn). By using CMC/CuO-Co2O3 and Cs@CMC/CuO-Co2O3, the distribution coefficients (Kd) for Ni, Fe, Ag and Zn were (41.166 and 6173.6 mLg-1), (136.3 and 1500 mLg-1), (20,739.1 and 1941.1 mLg-1) and (86.9 and 2333.3 mLg-1), respectively. Thus, Ni was highly adsorbed by Cs@CMC/CuO-Co2O3 beads. The metal ion adsorbed on the beads were converted into nanoparticles by treating with reducing agent (NaBH4) and named Ni/Cs@CMC/CuO-Co2O3. Further, the prepared nanoparticles-decorated beads (Ni/Cs@CMC/CuO-Co2O3) were utilized as nanocatalysts for the reduction of organic and inorganic pollutants (4-nitophenol, MO, EY dyes and potassium ferricyanide K3[Fe(CN)6]) in the presence of NaBH4. Among all catalysts, Ni/Cs@CMC/CuO-Co2O3 had the highest catalytic activity toward MO, EY and K3[Fe(CN)6], removing up to 98% in 2.0 min, 90 % in 6.0 min and 91% in 6.0 min, respectively. The reduction rate constants of MO, EY, 4-NP and K3[Fe(CN)6] were 1.06 × 10-1, 4.58 × 10-3, 4.26 × 10-3 and 5.1 × 10-3 s-1, respectively. Additionally, the catalytic activity of the Ni/Cs@CMC/CuO-Co2O3 beads was effectively optimized. The stability and recyclability of the beads were tested up to five times for the catalytic reduction of MO, EY and K3[Fe(CN)6]. It was confirmed that the designed nanocomposite beads are ecofriendly and efficient with high strength and stability as catalysts for the reduction of organic and inorganic pollutants.

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 silver­nickel 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 kapp 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).