Recent advances in graphene sheets as new generation of flame retardant materials

Polymeric and textile based materials constitute the majority of market products, however, due to their low thermal stability and high flammability hazards, their uses are limited in some applications. Therefore, flame retardant materials have to be dispersed as fillers in polymer matrix and coated on textile fabrics to enhance their fire safety and thermal stability. Graphene is two-dimensional materials and considered as a promising carbon nanomaterials with sp2-hybridization and with unique properties. In this review article conventional flame retardant and different methods of synthesis of graphene layers were summarized. Also, the possibility of use graphene sheets alone as flame retardant material for polymeric materials was reviewed and compared with other common nanofillers. Graphene sheets and their composite as flame retardant nanofillers for polymers and flame retardant coating for textiles are discussed in details. Synergistic flame retardant effect of use of nanoparticles decorated graphene sheets as flame retardant for polymer nanocomposites are discussed

pH-Sensitive Alginate/Carboxymethyl Chitosan/Aminated Chitosan Microcapsules for Efficient Encapsulation and Delivery of Diclofenac Sodium

To develop an effective pH-sensitive drug carrier, alginate (Alg), carboxymethyl chitosan (CMCs), and aminated chitosan (AmCs) derivatives were employed in this study. A simple ionic gelation technique was employed to formulate Alg-CMCs@AmCs dual polyelectrolyte complexes (PECs) microcapsules as a pH-sensitive carrier for efficient encapsulation and release of diclofenac sodium (DS) drug. The developed microcapsules were characterized by Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analyzer (TGA), and scanning electron microscope (SEM). The results clarified that formation of dual PECs significantly protected Alg microcapsules from rapid disintegration at colon conditions (pH 7.4), and greatly reduced their porosity. In addition, the dual PECs microcapsules can effectively encapsulate 95.4% of DS-drug compared to 86.3 and 68.6% for Alg and Alg-CMCs microcapsules, respectively. Higher DS-release values were achieved in simulated colonic fluid [SCF; pH 7.4] compared to those obtained in simulated gastric fluid [SGF; pH 1.2]. Moreover, the drug burst release was prevented and a sustained DS-release was achieved as the AmCs concentration increased. The results confirmed also that the developed microcapsules were biodegradable in the presence of the lysozyme enzyme. These findings emphasize that the formulated pH-sensitive microcapsules could be applied for the delivery of diclofenac sodium

Efficient loading and delivery of ciprofloxacin by smart alginate/carboxylated graphene oxide/aminated chitosan composite microbeads: In vitro release and kinetic studies

New composite microbeads were formulated as smart pH-sensitive vehicle for efficient delivery of ciprofloxacin (CIP) drug. Herein, carboxylated graphene oxide (CGO) was successfully impregnated into alginate (Alg) microbeads, which were then coated with aminated chitosan (AmCs) layer to form core–shell Alg/CGO@AmCs composite microbeads. Diverse analysis tools comprising FTIR, TGA, XRD and SEM were employed to characterize the developed carriers, while their swelling profiles and pH-sensitivity were examined under different pHs. The results clarified that increasing CGO and AmCs concentrations in microbeads matrix greatly protected Alg microbeads from fast disintegration at colon pH and prolonged their swelling time. Moreover, about 94.65 % of CIP drug was successfully loaded by Alg/CGO@AmCs composite microbeads compared to 61.95 % for Alg microbeads, confirming their reduced porosity. The in vitro CIP-release profiles were investigated in simulated gastrointestinal conditions. Furthermore, increasing AmCs concentration in the outer shell of composite microbeads clearly minimized the CIP burst release at the colon region and offered a sustained release performance. Besides, the CIP release mechanism was well-described by korsmeyer-peppas kinetic model. The cytotoxicity study confirmed the potential safety of the Alg/CGO@AmCs composite microbeads with human cell viability reached 98.98 %, suggesting their applicability as smart carriers for oral delivery of antibiotics

Preparation of Lambda-Cyhalothrin-Loaded Chitosan Nanoparticles and Their Bioactivity against Drosophila suzukii

The encapsulation of pesticides within nanoparticles is a promising approach of advanced technology in sustainable agriculture. Lambda-cyhalothrin (LC) was encapsulated by the ionotropic gelation technique into chitosan (CS)/tripolyphosphate (TPP) and CS/alginate (ALG) matrixes. CS-LC nanoparticles were characterized, and their efficacy was then evaluated against the key pest of soft fruits in Europe and the United States, Drosophila suzukii. The encapsulation efficiency (74%), nanoparticle yield (80%), polydispersity index (0.341), zeta potential (-23.1 mV) and particle size (278 nm) were determined at the optimum conditions. FTIR confirmed the cross-linkage between CS and TPP/ALG in the nanoparticles. The optimum formula recommended by the fractional factorial design was associated with the formulation variables of CS of high or low molecular weight, cross-linking agent (TPP), LC concentration (1.5% w/v) and stirring rate (1500 rpm), showing the highest desirability value (0.5511). CS-LC nanoparticles of the lowest particle size (278 nm) exhibited the highest percent mortality of D. suzukii males (86%) and females (84%), exceeding that caused by the commercial product (Karate-zeon® 10% CS) at 2 HAT. This is the first work to use the ionic gelation technique to make LC nanoparticles, to the best of our knowledge. The encapsulation of chemical pesticides within biodegradable polymeric nanoparticles could be helpful for establishing a sustainable IPM strategy with benefits for human and environmental health and the lifetime of pesticides

Sandwich-like construction of a new aminated chitosan Schiff base for efficient removal of Congo red

Abstract Herein, a novel sandwich-like α-ketoglutaric acid Schiff base-aminated chitosan composite (α-kGl-AmCsSB) was fabricated by reacting α-ketoglutaric acid and aminated chitosan. The as-fabricated α-kGl-AmCsSB was inspected by diversified characterization tools to determine its morphology, surface charge, and chemical composition as well as define the linkage pathway between α-kGl and AmCs. The SEM images demonstrated a spongy network of AmCs with interconnected pores structure which turned to a quite rough surface due to the linkage of α-kGl to the free amine groups of AmCs. Notably, the XPS and FTIR spectra suggested the linkage of α-kGl to the amine group of AmCs. The experimental results implied the superior adsorption efficiency of Congo red (CR) onto α-kGl-AmCsSB since the maximum adsorption capacity (q max) reached 434.78 mg/g at 25 °C and pH 3. Based on kinetics data, the adsorption of CR on α-kGl-AmCsSB followed pseudo-second-order model. Furthermore, D-R model infers that the CR adsorption onto α-kGl-AmCsSB occurred via physical interactions since the E value  72%. More importantly, the adsorption mechanism of CR onto α-kGl-AmCsSB was proposed and discussed. Ultimately, the novel sandwich-like α-kGl-AmCsSB exhibited advanced adsorption performance toward CR along with excellent reusability. Based on these results, we recommend more modifications on α-kGl-AmCsSB for exploiting its remarkable advantages and applying it on a large scale

Machine learning for membrane design in energy production, gas separation, and water treatment: a review

Membrane filtration is a major process used in the energy, gas separation, and water treatment sectors, yet the efficiency of current membranes is limited. Here, we review the use of machine learning to improve membrane efficiency, with emphasis on reverse osmosis, nanofiltration, pervaporation, removal of pollutants, pathogens and nutrients, gas separation of carbon dioxide, oxygen and hydrogen, fuel cells, biodiesel, and biogas purification. We found that the use of machine learning brings substantial improvements in performance and efficiency, leading to specialized membranes with remarkable potential for various applications. This integration offers versatile solutions crucial for addressing global challenges in sustainable development and advancing environmental goals. Membrane gas separation techniques improve carbon capture and purification of industrial gases, aiding in the reduction of carbon dioxide emissions.<br/

Advances in hydrogen storage materials: harnessing innovative technology, from machine learning to computational chemistry, for energy storage solutions

The demand for clean and sustainable energy solutions is escalating as the global population grows and economies develop. Fossil fuels, which currently dominate the energy sector, contribute to greenhouse gas emissions and environmental degradation. In response to these challenges, hydrogen storage technologies have emerged as a promising avenue for achieving energy sustainability. This review provides an overview of recent advancements in hydrogen storage materials and technologies, emphasizing the importance of efficient storage for maximizing hydrogen's potential. The review highlights physical storage methods such as compressed hydrogen (reaching pressures of up to 70 MPa) and material-based approaches utilizing metal hydrides and carbon-containing substances. It also explores design considerations, computational chemistry, high-throughput screening, and machine-learning techniques employed in developing efficient hydrogen storage materials. This comprehensive analysis showcases the potential of hydrogen storage in addressing energy demands, reducing greenhouse gas emissions, and driving clean energy innovation.<br/

Formulation and Antibacterial Activity Evaluation of Quaternized Aminochitosan Membrane for Wound Dressing Applications

Much attention has been paid to chitosan biopolymer for advanced wound dressing owing to its exceptional biological characteristics comprising biodegradability, biocompatibility and respectable antibacterial activity. This study intended to develop a new antibacterial membrane based on quaternized aminochitosan (QAMCS) derivative. Herein, aminochitosan (AMCS) derivative was quaternized by N-(2-Chloroethyl) dimethylamine hydrochloride with different ratios. The pre-fabricated membranes were characterized by several analysis tools. The results indicate that maximum surface potential of +42.2 mV was attained by QAMCS3 membrane compared with +33.6 mV for native AMCS membrane. Moreover, membranes displayed higher surface roughness (1.27 ± 0.24 μm) and higher water uptake value (237 ± 8%) for QAMCS3 compared with 0.81 ± 0.08 μm and 165 ± 6% for neat AMCS membranes. Furthermore, the antibacterial activities were evaluated against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Bacillus cereus. Superior antibacterial activities with maximum inhibition values of 80–98% were accomplished by QAMCS3 membranes compared with 57–72% for AMCS membrane. Minimum inhibition concentration (MIC) results denote that the antibacterial activities were significantly boosted with increasing of polymeric sample concentration from 25 to 250 µg/mL. Additionally, all membranes unveiled better biocompatibility and respectable biodegradability, suggesting their possible application for advanced wound dressing

A comprehensive review on LDH-based catalysts to activate persulfates for the degradation of organic pollutants

Abstract Degradation of organic contaminants into less toxic substances is the best option to remove these compounds rather than using conventional techniques. The sulfate radical-based-advanced oxidation process is an effective strategy that degrades organic contaminants by activating peroxymonosulfate (PMS). Such a strategy generates singlet oxygen (1O2), hydroxyl ( $$^ \bullet \!{{{\mathrm{OH}}}}$$ ∙ OH ), and sulfate ( $${{{\mathrm{SO}}}}_4^{ \bullet\! - }$$ SO 4 ∙ − ) radicals. $${{{\mathrm{SO}}}}_4^{ \bullet \!- }$$ SO 4 ∙ − is distinguished by its high oxidation selectivity and activity toward the degradation of organic contaminates compared to other radicals. Various catalysts are employed in PMS activation including layered doubled hydroxides (LDHs), which are characterized by their facile synthesis and high catalytic activity. This review article is the first attempt to compile the recent progress in the degradation of common organic pollutants including aromatic compounds, pharmaceutical residues, and dyes via the PMS activation using LDH-based catalysts. The degradation pathways, reaction parameters’ influence, stability of LDHs, and comparisons between different LDH-based catalysts are investigated in this work

Iron oxide nanoparticles and their pharmaceutical applications

The importance of different polymorphic forms of iron oxide nanoparticles attracted a lot of attentions in various applications due to their unique electrical, optical and magnetic properties. Moreover, the excellent biocompatibility, high surface area, spherical shape, tunable nanoscale size and the availability of synthesis route make them desirable in various biological and pharmaceutical applications. To this aim, in this review, different synthesis methods of iron oxide nanoparticles were discussed, also the main characterization techniques used for elucidation of the iron oxide nanoparticles were reviewed. The exploitation of iron oxide nanoparticles-based systems as anticancer, antiviral, antimicrobial agents and its involvement in drug delivery system were reviewed in details. Additionally, the influence of nanoparticles size and the reagent type and conditions utilized in synthesis and their pharmaceutical applications was highlighted