Preparation of Isopropyl Acrylamide Grafted Chitosan and Carbon Bionanocomposites for Adsorption of Lead Ion and Methylene Blue

Biopolymeric Nanocomposites for Wastewater Remediation: An Overview on Recent Progress and Challenges

Essential for human development, water is increasingly polluted by diverse anthropogenic activities, containing contaminants like organic dyes, acids, antibiotics, inorganic salts, and heavy metals. Conventional methods fall short, prompting the exploration of advanced, cost-effective remediation. Recent research focuses on sustainable adsorption, with nano-modifications enhancing adsorbent efficacy against persistent waterborne pollutants. This review delves into recent advancements (2020-2023) in sustainable biopolymeric nanocomposites, spotlighting the applications of biopolymers like chitosan in wastewater remediation, particularly as adsorbents and filtration membranes along with their mechanism. The advantages and drawbacks of various biopolymers have also been discussed along with their modification in synthesizing biopolymeric nanocomposites by combining the benefits of biodegradable polymers and nanomaterials for enhanced physiochemical and mechanical properties for their application in wastewater treatment. The important functions of biopolymeric nanocomposites by adsorbing, removing, and selectively targeting contaminants, contributing to the purification and sustainable management of water resources, have also been elaborated on. Furthermore, it outlines the reusability and current challenges for the further exploration of biopolymers in this burgeoning field for environmental applications.

A significant antibiofilm and antimicrobial activity of chitosan-polyacrylic acid nanoparticles against pathogenic bacteria

Chitosan is known to exert antimicrobial activity without the need for any chemical modification; however, new derivatives of chitosan can be created to target multi-drug resistant bacteria. In this study, chitosan (CS) was cross-linked with sodium tripolyphosphate to form nanoparticles, which were then coated with polyacrylic acid (PAA). The SEM images revealed that the CS-PAA nanoparticles had spherical shapes with smooth surfaces and the size of the dried nanoparticles was approximately 222 nm. Biofilm formation was significantly inhibited by 0.5 mg/mL of CS-PAA. In-situ optical microscopy showed that CS-PAA nanoparticles inhibited the bacterial biofilm formation in Campylobacter jejuni, Pseudomonas aeruginosa, and Escherichia coli after a single treatment with 40 μg. Additionally, 20 µg of CS-PAA nanoparticles demonstrated antibacterial activity against the growth of C. jejuni, P. aeruginosa, and E. coli with notable inhibitory zones of 9, 12, and 13 mm, respectively (P < 0.01). The development of a novel and ecofriendly method for the preparation of chitosan nanoparticles through an interaction of chitosan with PAA shows promise tool to combat bacterial infections and validates effective antibacterial and antibiofilm properties against antibiotic resistant pathogens.

Impact of the Configurational Microstructure of Carboxylate-Rich Chitosan Beads on Its Adsorptive Removal of Diclofenac Potassium from Contaminated Water

A novel adsorbent-contaminant system was investigated for its ability to remove a contaminant of emerging concern, diclofenac potassium, from contaminated water. Bio-based crosslinked chitosan beads functionalized with poly(itaconic acid) side chains were examined for their potential to remove the emerging contaminant. To evaluate the impact of the polymeric microstructure on its adsorptive capacity, several adsorbent samples were prepared using different combinations of initiator and monomeric concentrations. Fourier Transform Infrared (FTIR) analysis confirmed the crosslinking of the chitosan chains and the incorporation of the carboxylic groups on the surface of the final chitosan beads. After the grafting copolymerization process, an additional peak at 1726 cm-1 corresponding to the carboxylic C=O groups of the grafted chains appeared, indicating the successful preparation of poly(IA)-g-chitosan. Thermal stability studies showed that the grafting copolymerization improved the thermal stability of the beads. X-ray and Scanning Electron Microscopy confirmed the successful grafting of the itaconic acid on the surface of the beads. The study revealed that the higher the initiator concentration, the greater the number of side chains, whereas the higher the monomeric concentration, the longer the length of these side chains. The adsorption mechanism involved hydrogen bonding to the carboxylic groups of the grafted chains along with n-π* stacking interaction between the amino group of the chitosan and the aromatic rings of diclofenac potassium. The adsorption efficiencies of diclofenac potassium onto the grafted beads were significantly improved compared to the unfunctionalized chitosan beads, reaching values above 90%. The removal efficiency of grafted chitosan increased with an increase in the concentration in the range of 10-30 ppm and then flattened out in the range of 30-50 ppm. The removal efficiencies of 1-50 ppm of DCF ranged between about 75% and 92% for the grafted chitosan and 30-45% for the crosslinked chitosan. Rapid adsorption occurred within 20 min for all grafted sample combinations, and the adsorption kinetics followed a pseudo-second-order model with qe values ranging from 28 to 44.25 g/mg and R2 values greater than 0.9915. The results highlight the potential of grafted chitosan beads in removing emerging contaminants from contaminated water without harming the environment.

Preparation and performance of bionanocomposites based on grafted chitosan, GO and TiO2-NPs for removal of lead ions and basic-red 46

Wastewater rich in heavy metals and organic compounds represents one of the essential environmental pollutants. Therefore, a practical approach is to fabricate eco-friendly polymer-based systems with a high ability to absorb pollutants. Herein, bionanocomposites consisting of chitosan (Cs) grafted by various monomers, such as acrylamide (Am), acrylic acid (AA), and 4-styrene sulfonic acid (SSA), and hybrid nanoparticles of graphene oxide/titanium dioxide nanoparticles (GO@TiO₂-NPs) were fabricated. The prepared nanomaterials and bionanocomposites characterized via various tools. The data illustrated that the prepared GO had a thickness of 10 nm and TiO₂-NPs had a diameter of 25 nm. In addition, the grafted chitosan (gCs) using Am and SSA had the largest surface area (gCs2; 22.89 nm) and its bionanocomposite (NC5; 104.79 nm). In addition, the sorption ability of the 0.15 g of prepared bionanocomposites to the (100 mg/L) of lead ions (Pb²⁺) and (25 mg/L) of basic-red 46 (BR46) under various conditions has been studied. The results showed that gCs3 and NC5 had the highest adsorption of Pb²⁺ (79.54 %) and BR46 (79.98 %), respectively. The kinetic study results of the sorbents obeyed the Pseudo second-order model. In contrast, the isothermal study followed the Freundlich adsorption model for Pb²⁺ and the Langmuir adsorption model for BR46.