Adsorption and antibacterial studies of a novel hydrogel adsorbent based on ternary eco-polymers doped with sulfonated graphene oxide developed from upcycled plastic waste.

A novel ternary blended polymer composed of cost-effective and readily available polymers was synthesized using poly (vinyl alcohol) (PVA), iota carrageenan (IC), and poly (vinyl pyrrolidone) (PVP). Sulfonated graphene oxide (SGO), prepared from recycled drinking water bottles, was utilized as a doping agent. Varying amounts (1-3 wt%) were combined into the polymer matrix. The produced hydrogel film was examined as a potential adsorbent hydrogel film for the removal of methylene blue (MB) and Gentamicin sulfate (GMS) antibiotic from an aqueous solution. The experimental results demonstrate that the presence of SGO significantly increased the adsorption efficiency of PVA/IC/PVP hydrogel film. The antimicrobial tests revealed that the PVA/IC/PVP-3% SGO hydrogel film exhibited the most potent activity against all the tested pathogenic bacteria. However, the adsorption results for MB and GMS showed that the addition of 3 wt% SGO resulted in a removal percentage that was a two fold increase in the removal percentage compared with the undoped PVA/IC/PVP hydrogel film. Furthermore, the response surface methodology (RSM) model was utilized to examine and optimize several operating parameters, including time, pH of the solution, and initial pollutant concentration. The adsorption kinetics were better characterized by the pseudo-second-order kinetics model. The composite film containing 3 wt% SGO had a maximum adsorption capacity of 606 mg g-1 for MB and 654 mg g-1 for GMS, respectively. The generated nanocomposite hydrogel film demonstrated promising potential for application in water purification systems.

Development of hybrid green nanocomposite polymeric beads doped with nano sulfated zirconia for effective removal of Cefotaxime antibiotic from aqueous solution.

Adsorption efficiency of Cefotaxime by novel nanocomposites beads composed of iota carrageenan (IC), sulfonated poly vinyl alcohol (SPVA) and nano sulfated zirconia (SZrO2) was evaluated in this study. SZrO2 was synthesized from solvent-free and easy calcination technique then embedded with 1-2.5 wt.% into the polymeric matrix. A batch adsorption experiment was carried out to investigate the effects of dosage, pH, beginning concentration, and time on Cefotaxime antibiotic adsorption. The ideal conditions to achieve complete removal are 88.97 mg L-1 initial cefotaxime concentration at time 3.58 h with 11.68 mg of beads composite with 2.5 wt.% of SZrO2. The pseudo second order kinetics model better illustrated the adsorption of cefotaxime on nanocomposite beads, and the maximum adsorption capacity are 659 mg g-1 for the composite with 2.5 wt.% of SZrO2. The mechanism of adsorption process depend mainly on the interactions between the different functional groups of SPVA, IC and SZrO2. The nanocomposites beads also exhibit excellent reproducibility after ten adsorption cycles. This type of nanocomposites beads can be easily separated from water without leaving any residue, verifying this novel nanocomposite beads has strong potential in water treatment for the antibiotic contaminant removal.

Polyvinyl Alcohol/Polyaniline/Carboxylated Graphene Oxide Nanocomposites for Coating Protection of Cast Iron in Simulated Seawater.

In our daily lives and product manufacturing, metal corrosion causes significant economic losses. Numerous polymeric composite coatings have been shown to be resistant to harsh environments, such as those found in marine environments. In this study, a composite of polyvinyl alcohol/polyaniline blend loaded with carboxylated graphene was explored in the search for long-lasting coatings to resist electrochemical deterioration of cast iron in desalination systems of saltwater. Polyvinyl alcohol/polyaniline/carboxylated graphene oxide nanocomposite was spin-coated onto cast iron samples. Electrochemical impedance spectroscopy (EIS) and electrochemical DC corrosion testing with a three-electrode system were used to study corrosion resistance in uncoated and coated cast iron samples. The results exhibit effective corrosion protection properties. The EIS data indicated better capacitance and higher impedance values for coated samples than bare metal, depicting enhanced corrosion resistance against the saline environment. Tafel analysis confirmed a significant decrease in the corrosion rate of the PVA/PANI/GO-COOH coated sample.

Sustainable Microbial and Heavy Metal Reduction in Water Purification Systems Based on PVA/IC Nanofiber Membrane Doped with PANI/GO.

Effective and efficient removal of both heavy metal pollutants and bacterial contamination from fresh water is an open issue, especially in developing countries. In this work, a novel eco-friendly functional composite for water treatment application was investigated. The composite consisted of electrospun nanofiber membrane from blended polyvinyl alcohol (PVA)/iota carrageenan (IC) polymers doped with equal concentrations of graphene oxide (GO) nanoparticles and polyaniline (PANI). The effectiveness of this composite as a water purification fixed-bed filter was optimized in a batch system for the removal of cadmium (Cd+2) and lead (Pb+2) ions, and additionally characterized for its antimicrobial and antifungal properties and cytotoxicity effect. The fiber nanocomposite exhibited efficient antibacterial activity, with maximum adsorption capacity of about 459 mg g-1 after 120 min for Cd+2 and of about 486 mg g-1 after 90 min for Pb+2. The optimized conditions for removal of both metals were assessed by using a response surface methodology model. The resulting scores at 25 °C were 91.4% (Cd+2) removal at 117 min contact time for 89.5 mg L-1 of initial concentration and 29.6 cm2 membrane area, and 97.19% (Pb+2) removal at contact time 105 min for 83.2 mg L-1 of initial concentration and 30.9 cm2 nanofiber composite membrane. Adsorption kinetics and isotherm followed a pseudo-second-order model and Langmuir and Freundlich isotherm model, respectively. The prepared membrane appears to be promising for possible use in domestic water purification systems.

Design of Promising Green Cation-Exchange-Membranes-Based Sulfonated PVA and Doped with Nano Sulfated Zirconia for Direct Borohydride Fuel Cells.

The direct borohydride fuel cell (DBFC) is a low-temperature fuel cell that requires the development of affordable price and efficient proton exchange membranes for commercial purposes. In this context, super-acidic sulfated zirconia (SO4ZrO2) was embedded into a cheap and environmentally friendly binary polymer blend, developed from poly(vinyl alcohol) (PVA) and iota carrageenan (IC). The percentage of SO4ZrO2 ranged between 1 and 7.5 wt.% in the polymeric matrix. The study findings revealed that the composite membranes' physicochemical features improved by adding increasing amounts of SO4ZrO2. In addition, there was a decrease in the permeability and swelling ratio of the borohydride membranes as the SO4ZrO2 weight% increased. Interestingly, the power density increased to 76 mW cm-2 at 150 mA cm-2, with 7.5 wt.% SO4ZrO2, which is very close to that of Nafion117 (91 mW cm-2). This apparent selectivity, combined with the low cost of the eco-friendly fabricated membranes, points out that DBFC has promising future applications.

Novel scaffold based graphene oxide doped electrospun iota carrageenan/polyvinyl alcohol for wound healing and pathogen reduction: in-vitro and in-vivo study.

Wound healing is a complicated multicellular process that involves several kinds of cells including macrophages, fibroblasts, endothelial cells, keratinocytes and platelets that are leading to their differentiation towards an anti-inflammatory response for producing several chemokines, cytokine and growth factors. In this study, electrospun nanofiber scaffold named (MNS) is composed of polyvinyl alcohol (PVA)/iota carrageenan (IC) and doped with partially reduced graphene oxide (prGO) that is successfully synthesized for wound healing and skin repair. The fabricated MNS was tested in case of infection and un-infection with E. coli and Staphylococcus and in both of the presence and in the absence of yeast as a natural nutritional supplement. Numerous biochemical parameters including total protein, albumin, urea and LDH, and hematological parameters were evaluated. Results revealed that the MNS was proved to be effective on most of the measured parameters and had exhibited efficient antibacterial inhibition activity. Whereas it can be used as an effective antimicrobial agent in wound healing, however, histopathological findings confirmed that the MNS caused re-epithelialization and the presence of yeast induced hair follicles growth and subsequently it may be used to hide formed head wound scar.

Novel Crosslinked Sulfonated PVA/PEO Doped with Phosphated Titanium Oxide Nanotubes as Effective Green Cation Exchange Membrane for Direct Borohydride Fuel Cells.

A direct borohydride fuel cell (DBFC) is a type of low temperature fuel cell which requires efficient and low cost proton exchange membranes in order to commercialize it. Herein, a binary polymer blend was formulated from inexpensive and ecofriendly polymers, namely polyethylene oxide (PEO) and poly vinyl alcohol (PVA). Phosphated titanium oxide nanotube (PO4TiO2) was synthesized from a simple impregnation-calcination method and later embedded for the first time as a doping agent into this polymeric matrix with a percentage of 1-3 wt%. The membranes' physicochemical properties such as oxidative stability and tensile strength were enhanced with increasing doping addition, while the borohydride permeability, water uptake, and swelling ratio of the membranes decreased with increasing PO4TiO2 weight percentage. However, the ionic conductivity and power density increased to 28 mS cm-1 and 72 mWcm-2 respectively for the membrane with 3 wt% of PO4TiO2 which achieved approximately 99% oxidative stability and 40.3 MPa tensile strength, better than Nafion117 (92% RW and 25 MPa). The fabricated membrane with the optimum properties (PVA/PEO/PO4TiO2-3) achieved higher selectivity than Nafion117 and could be efficient as a proton exchange membrane in the development of green and low cost DBFCs.