NiO nanoparticle doped-PVA-MF polymer nanocomposites: Preparation, Congo red dye adsorption and antibacterial activity

Optical, thermal, mechanical, and antibacterial properties of polyvinyl alcohol/sodium alginate/ZnMn2O4 nanocomposites films for various optical devices and food packaging applications

This work involves preparing zinc manganite nanoparticles (ZnMn2O4 NPs) using the Sol-gel method. Polymer nanocomposites of polyvinyl alcohol (PVA)/Sodium alginate (NaAlg)- ZnMn2O4 NPs were created using the solution casting technique. The polymer nanocomposites films were made with varying weight percentages of ZnMn2O4 nanoparticles. With the addition of nanofiller, the reduced direct and indirect energy band gap values and increased Urbach energy values were discovered in the UV-Vis data. XRD data showed a reduction in crystallinity degree with dopant. ZnMn2O4 NPs had a strong interaction with PVA/NaAlg blend, as confirmed by FTIR. The addition of ZnMn2O4 NPs led to improved thermal stability of the polymer nanocomposites films. Additionally, the nanocomposites films' mechanical characteristics were examined. The loading of ZnMn2O4 nanoparticles has been associated with an increasing trend in the mechanical properties of the nanocomposites, including its toughness, Young's modulus, Tensile strength (Ts), and elongation. The antibacterial activity of the nanocomposites against fungus and bacteria was studied. Additionally, PVA/NaAlg-ZnMn2O4 nanocomposites films had good antibacterial characteristics against environmental microorganisms such as Gram-positive (G+) S. aureus and Gram-negative(G-) E. coli bacteria as well as fungi C. albicans and A. niger. It was observed that the biodegradability of the nanocomposite films was lower compared to the pure PVA/NaAlg film. Compared to pure film, the water solubility was decreased upon the addition of ZnMn2O4 NPs. After ZnMn2O4 was added to the pure blend, the WVTR decreased. The produced polymer nanocomposites films appear to be a promising material for food packing, according to these results.

Photocatalytic degradation of methyl blue dye with H2O2 sensing

A condensation polymer (urea-formaldehyde resin) passivated ZnO nanoparticles were used as an efficient photocatalyst for methyl blue degradation in the presence of H2O2 involving a Fenton-like reaction. The formation of OH˙ radicals were attributed to the pivotal factor for the degradation process. The method was easy and recyclable. The dose of photocatalyst, initial dye concentration, pH variation, variations of the composition of the photocatalyst, and the effect of scavengers were gauged. The degraded product was highly fluorescent and fluorometric detection of H2O2 was achieved along with a colorimetric recognition pathway. No other dye could be degraded under similar experimental conditions, implying the novel utility of methyl blue for environmental remediation.

Fabrication of a corn stalk derived cellulose-based bio-adsorbent to remove Congo red from wastewater: Investigation on its ultra-high adsorption performance and mechanism

A cellulose-based bio-absorbent with various and plenty of amino groups was successfully prepared from corn stalk to achieve quantitative removal of Congo red from wastewater with wide pH values (5 ≤ pH ≤ 10). The maximum removal amount was 8.0 mmol·g^-1 (5572 mg·g^-1) under pH = 6.0 and 45 °C, which was obviously higher than reported absorbents. Investigation on dynamic adsorption and recyclability in authentic wastewater found that the removal efficiency of Congo red was >98 % within 180 min and decreased slightly in industrial water after five cycles, denoting this adsorbent with great potential for environmental application. The characterization results proved that 7.58 mmol·g^-1 of different amino groups (-NH₂, -NH- and -NR₂) were introduced on adsorbent surface by two steps of modification and were the major functional groups for adsorption of Congo red. The inferred adsorption mechanism revealed that Congo red could be adsorbed equivalently on the amino groups by strong electrostatic interactions or hydrogen bonds. Different amino groups played different roles in adsorption due to great differences in protonation ability in 5 ≤ pH ≤ 10. The study was expected to high-efficiently remove Congo red from acidic or alkaline wastewater, and offered an alternative strategy for biowaste treatment of corn stalks in a high value-added manner.

Functionalization of pine sawdust biochars with Mg/Al layered double hydroxides to enhance adsorption capacity of synthetic azo dyes: Adsorption mechanisms and reusability

This study determined that the adsorption of azo dyes, Methyl Orange (MO) and Sunset Yellow FCF (SYF), using the pristine pine sawdust biochar (PSB) and post-modified PSB with Mg/Al layered double hydroxides (PSB-LDH_MgAl) was examined to offer valuable information into the differences in their adsorption mechanisms. Although a lower specific surface area of PSB-LDH_MgAl (147.2 m² g^-1) than PSB (495.7 m² g^-1), LDH_MgAl were successfully functionalized on the PSB surface through co-precipitation, which was highly related to the improvements of adsorption capacity of PSB-LDH_MgAl toward MO and SYF. The MO and SYF adsorption kinetics by PSB and PSB-LDH_MgAl were confirmed to the pseudo-second-order and considered chemisorption. The adsorption capacity of MO and SYF adsorbed onto PSB-LDH_MgAl (MO = 21.8 mg g^-1, SYF = 23.6 mg g^-1) were significantly higher than that of PSB (MO = 2.2 mg g^-1, SYF = 1.6 mg g^-1). The adsorption isotherms of MO and SYF by PSB were well fitted by Freundlich isotherm, whereas the MO and SYF via PSB-LDH_MgAl were by Langmuir isotherm. Even after 3 adsorption-desorption cycles using desorbents, the PSB-LDH_MgAl remained excellent reusability (reuse efficiency: >81.2%). These findings suggest that post-modification with LDH_MgAl might accelerate the adsorption performance (i.e., electrostatic interaction) of azo dyes to PSB in water.

Synthesis of novel PANI/PVA-NiCu composite material for efficient removal of organic dyes

The present work aims the synthesis of a novel, low cost, and environmentally friendly PANI/PVA-CuNi composite by chemical oxidative polymerization of aniline monomer and polyvinyl alcohol (PVA) as film matrix; several percentages of copper (Cu) and Nickel (Ni) were used. UV-Visible spectroscopy, FTIR, SEM-EDX, and TGA were used to characterize the nanocomposites. While PANI/PVA-CuNi nanocomposites were investigated in adsorption experiments of methylene blue (MB) under different controlled conditions (time reaction, adsorbent dosage, initial dye concentration, stirring speed, temperature, and pH of the medium) also various kinetic models were employed to evaluate the efficiency of the adsorption. The results revealed that the10 mg of PANI/PVA-Cu₅₀N_i50 and PANI/PVA-Ni composites Catalyst removed (94% and 93% of methylene blue in 180 min respectively at 10^-5 M initial concentration of dye, pH of 13, stirring speed of 150 rpm, the temperature of 301 k. the kinetics data were properly fitted with the pseudo second-order model with a correlation coefficient of 0.98262 and 0.95881 using PANI/PVA-Cu₅₀N_i50 and PANI/PVA-Ni, respectively.

Delonix regia seed pod-an efficient biosorptive candidate toward the removal of Rhodamine B from simulated wastewater: characterization, kinetics, and equilibrium approach

This study focused on the comparative analysis of biosorption performance of Delonix regia seed pod toward the removal of Rhodamine B (RB) from simulated solution using native (DRSP) and chemically treated form (ADRSP). The surface morphology, structural analysis, textural properties, and thermal analysis of DRSP and ADRSP were examined using scanning electron microscopy (SEM), BET analysis, Fourier transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA), respectively. FTIR analysis concluded that surface functional groups like hydroxyl -OH stretching, C-N stretching, and C = C stretching of the aromatic ring were largely responsible for the attachment of RB. The chemical treatment enhanced the surface morphology of D. regia seed in terms of heterogeneity, distinct depth cavities, and irregular pores responsible for RB biosorption. The biosorption of RB was investigated using parametric analyses such as solution pH, biosorbent dosage, contact time, initial RB concentration, and operating temperature. The obtained equilibrium data were fitted with different isotherm and kinetic models. Langmuir isotherm model and pseudo-second-order kinetic were well suitable for the biosorption of RB using DRSP and ADRSP. The maximum monolayer biosorption capacities (mg/g) of DRSP and ADRSP were predicted to be 39.37 and 60.61, respectively. Using thermodynamic principles, the removal of RB was found to be thermodynamically feasible, endothermic, and spontaneous process. The results of the present study proved that DRSP and ADRSP can be identified as promising biosorbents for the removal of RB.

Antimicrobial and antifungal properties of NiCu-PANI/PVA quaternary nanocomposite synthesized by chemical oxidative polymerization of polyaniline

Increasing antimicrobial resistance has led to use of novel technologies such as nanomaterials and nanocomposites that have shown effective antimicrobial and/or antifungal activities against several gram-positive and gram-negative bacteria. There have been limited studies on antimicrobial properties of the combined polymer nanocomposites with transitional bimetallic nanoparticles such as nickel (Ni) and copper (Cu). Thus, the main objective of this study was to synthesis, characterize and investigate the antibacterial and antifungal properties of NiCu-PANI/PVA nanocomposite. The nanocomposite films with different amount of Ni and Cu salts were synthesized by chemical oxidative polymerization of polyaniline using HCl as oxidant and PVA as a stabilizer. Optical, chemical composition, and morphological characteristics as well as thermal stability were evaluated using UV-Visible, FTIR, SEM-EDX, and TGA analyses. Antimicrobial properties were then determined using the disc diffusion assay against gram-negative bacteria (i.e., Escherichia coli ATCC 25922, Klebsiella pneumonia ATCC 700603, Proteus sp.,) and gram-positive bacteria (i.e., Staphylococcus aureus ATCC 2593). Fungal plant pathogens including Aspergillus niger and Fusarium oxysporum f. sp. pisi were also evaluated for determination of antifungal activity of NiCu-PANI/PVA films. Among the synthesized films, Ni₆₅Cu₃₅-PANI/PVA showed excellent antibacterial activity against all the bacteria strains examined in this study. The diameters of inhibition zones for Escherichia coli ATCC 25922, Klebsiella pneumoniae ATCC 700603, Proteus sp., and Staphylococcus aureus ATCC 2593 were 23, 23, 17, and 18 mm, respectively indicating good antibacterial activities. Additionally, NiCu-PANI/PVA, particularly the films with higher Cu intake, showed better antifungal activity against Fusarium oxysporum f. sp. pisi. However, NiCu-PANI/PVA was ineffective against Aspergillus niger.

Chitosan-based nanocomposite films incorporated with NiO nanoparticles: Physicochemical, photocatalytic and antimicrobial properties

The aim of this research was to fabricate active nanocomposite films by incorporation of nickel oxide nanoparticles (NiONPs) (3, 6 and 9% w/w) into the chitosan-based films. The NiONPs were synthesized by solution combustion method and the films were prepared by solvent casting method. The formation of new interactions and increasing of films' crystallinity were confirmed by FT-IR and XRD analyses. Uniform dispersion of NiONPs at lower concentrations and their aggregation at level of 9% was confirmed by FE-SEM observations. Water barrier properties, tensile strength, thermal properties and surface hydrophobicity of films enhanced by addition of 6% NiONPs. Photocatalytic activity of nanocomposites was confirmed by absorption of 72% of methyl orange during 270 min under UV irradiation. The nanocomposite films exhibited good antibacterial activity against gram-positive (S. aureus) and gram-negative (S. typhimurium) bacteria. Therefore, the chitosan-NiONPs nanocomposite films could be used for active food packaging applications and photodecolorization purposes.

New and efficient NiO/chitosan/polyvinyl alcohol nanocomposites as antibacterial and dye adsorptive films

The development of composite films with enhanced antibacterial and dye decolorization properties for water treatment has attracted a great attention. In this study, nickel oxide/chitosan/polyvinyl alcohol nanocomposite films containing different weight percentage of NiO nanoparticles with a dual functionality, removal of toxic dye and antibacterial properties, were prepared. Methyl orange (MO) was selected as a target pollutant. Additionally, the antimicrobial activity of the films against two Gram positive bacteria (Staphylococcus aureus and Bacillus cereus) and two Gram negative bacteria (Escherichia coli and Salmonella Typhimurium) was studied. The prepared samples were characterized by XRD, HRTEM, FESEM, ATR-FTIR, UV-Vis spectroscopy, and dielectric measurements. The morphological examination proved that the nanocomposite film has more porous structure compared to the unmodified chitosan/PVA. The antimicrobial tests indicated that the modified chitosan/PVA films have higher activity than pure chitosan/PVA toward all the tested pathogenic bacteria. The impact of the NiO amount (0.5, 1.5, 3, and 5 wt%), contact time (0-150 min), and adsorbent dose (40, 80, and 100 mg) on the removal of MO was studied. Dye adsorption results proved that the incorporation of 5 wt% NiO led to more than 2 fold increase in the dye removal percentage in comparison with the unmodified PVA/chitosan film.

Zero Valent Iron Nanoparticle-Loaded Nanobentonite Intercalated Carboxymethyl Chitosan for Efficient Removal of Both Anionic and Cationic Dyes

A zero valent iron-loaded nano-bentonite intercalated carboxymethyl chitosan (nZVI@nBent-CMC) composite was fabricated and characterized by FT-IR, TEM, TEM-EDX, XRD, BET surface area, and zeta potential measurements. The as-fabricated nZVI@nBent-CMC composite exhibited excellent removal efficiency for both anionic Congo red (CR) dye and cationic crystal violet (CV) dye. The maximum uptake capacities of CR and CV onto the nZVI@nBent-CMC composite were found to be 884.95 and 505.05 mg/g, respectively. The adsorption process of both dyes well fitted with the Langmuir isotherm model and pseudo-second order kinetic model. Thermodynamic data clarified that the adsorptions of both CR and CV onto the nZVI@nBent-CMC composite are spontaneous processes. Moreover, the adsorption of CR onto the nZVI@nBent-CMC composite was found to be an exothermic process while that of CV is an endothermic process. The nZVI@nBent-CMC composite also exhibited excellent reusability for both studied dyes without noticeable loss in the removal efficiency, suggesting its validity to remove both anionic and cationic dyes from wastewater.

Adsorption properties of β-cyclodextrin modified hydrogel for methylene blue

With the development of dye and printing, production wastewater has become one of the most primary pollution sources of water and soil pollution. Most of the dyes are toxic substances, which have the "three-way" effect of carcinogenic, teratogenic and mutagenic. Therefore, it is a very difficult but significant issue to deal with the dye in the wastewater. Here, we report a study on low-cost, high-capacity hydrogels that remove water-soluble dyes. The hydrogel is prepared by crosslinking the β-cyclodextrin and functional monomer: acrylamido and 2-acrylamide-2-methylpropane sulfonic acid by aqueous solution polymerization, meanwhile, alkaline hydrolysis is also an important step for adsorption performance. After alkaline hydrolysis, the amide and sulfonic groups in the hydrogel were converted into carboxylate and sulfonate, which was beneficial to the adsorption of cationic dyes. This polymer could remove 96.58% methylene blue (400 mg/L) and only requires 0.02 wt%. Its maximum adsorption capacity for methylene blue could reach 2638.22 mg/g under equilibrium condition. It is the most powerful adsorbent used to treat dye wastewater, according to the report. It also provides some references for hydrogel treatment of dye wastewater.