Synthesis and characterization of chitosan-g-methacrylic acid and studies of its additional physicochemical properties, such as swelling, metal-ion sorption, and flocculation behavior

Synthesis of 2,5-furandicarboxylic acid-enriched-chitosan for anti-inflammatory and metal ion uptake

The main aim of the present study is to synthesize a hitherto unreported polymer of chitosan (CS) and 2,5-furandicarboxylic acid (FDCA) derived from renewable biomass resources. For this purpose, CS was chosen which had -NH₂ groups as abundant active sites. Synthesis of 2,5-furandicarboxylic acid-enriched-chitosan polymer (CS-FDCA) was carried out by reaction involving EDC-NHS coupling reagents. The structure of CS-FDCA polymer was confirmed by various characterization techniques such as Fourier-transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance (¹H NMR), X-ray powder diffraction (XRD), high resolution-field emission scanning electron microscope (HR-FESEM), and thermogravimetric analysis (TGA). Moreover, CS and CS-FDCA were scrutinized to examine their efficacies towards ameliorate inflammation via detection of lipopolysaccharide (LPS) induced nitric oxide (NO) production. As compared to CS, CS-FDCA with low concentration (1.0 μM) exhibited the better efficacy to reduce the NO production. Furthermore, CS-FDCA polymer showed high as 12.6% of Cu²⁺ ion uptake while CS showed 9.2% of Cu²⁺ ion uptake. Overall, it can be inferred that CS-FDCA polymer is expected to be used for biomedical application and for the removal of metal contaminants from industrial wastewater.

A review on chitosan-based flocculants and their applications in water treatment

In recent years, the use of chitosan and its derivatives as flocculants in water treatment has received considerable attention due to their many advantages, including their widespread availability, environmental friendliness, biodegradability, and prominent structural features. However, it is a significant strategy for selection and design of the high-performance materials on the basis of their structure-activity relationships. Here we describe several of the chemical modification methods commonly used to prepare chitosan-based flocculants. These methods allow convenient control and adjustment of the structures of the obtained materials to meet the different practical requirements. The influence of structural elements of the chitosan-based flocculants on their flocculation properties are emphasized in this review by examining different flocculation mechanisms and their applications in the treatment of various wastewaters containing different pollutants (insoluble suspended colloids but also dissolved matters). Above all, the chitosan-based flocculants with proper structures by precise structure control bear great application potentials in water treatment.

Novel biodegradable flocculanting agents based on pullulan

New copolymers with different grafted cationic chain content and length were synthesized by graft-polymerization of (3-acrylamidopropyl)-trimethylammonium chloride onto pullulan in aqueous solution, using potassium persulfate as an initiator. Their flocculation efficiency was studied in a clay suspension as a function of the grafted chains content and length as well as of some flocculation parameters: the polycation dose, the settling time, the parent solution concentration of polycation. All the polysaccharide samples showed flocculation ability: the higher the grafted cationic chain content and length the lower the amount of pullulan derivative was required for reaching the maximum clarity degree (of about 100%). This finding together with the negative value of the zeta potential and floc size measurements, at the optimum polymer dose, point to contributions from both neutralization and bridging mechanisms for flocculation process. The residual turbidity values also varied with the settling time and the parent solution concentration of polymer.