Chitosan Grafted Adsorbents for Diclofenac Pharmaceutical Compound Removal from Single-Component Aqueous Solutions and Mixtures

Abstract

The main purpose of this study was to investigate the synthesis of some cross-linked carboxyl-grafted chitosan derivatives to be used as selective adsorbents for diclofenac (DCF) pharmaceutical compounds from aqueous mixtures. Four different materials were synthesized using succinic anhydride (CsSUC), maleic anhydride (CsMAL), itaconic acid (CsITA), and trans-aconitic acid (CsTACON) as grafting agents. After synthesis, scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD) were performed before and after DCF adsorption. In addition, a complete adsorption evaluation was carried out for all materials studying some important parameters. The optimum pH was 4; the amino groups of DCF can be protonated at pH = 4 (–NH+), so this groups can easily attract the clear negatively carboxyl moieties (–COO−) of the chitosan adsorbents. The Qm for CsTACON was higher than those of the other materials, at all temperatures studied. By altering the temperature from 25 to 35 °C, an increase (16%) of Qm (from 84.56 to 98.34 mg g−1) was noted, while similar behavior was revealed after a further increase of temperature from 35 to 45 °C, improving by 5% (from 98.34 to 102.75 mg g−1). All isotherms were fitted to Langmuir, Freundlich, and Langmuir-Freundlich (L-F) models). In addition, a kinetic model was proposed taking into account not only the interactions but also the diffusivity of the molecule (DCF) into the polymeric network. The behavior of the prepared chitosan materials in simultaneously removing other compounds (synergetic or antagonistic) was also evaluated by experiments performed in mixtures. DCF presented the highest removal from the mixture in the order: CsTACON (92.8%) > CsITA (89.5%) > CsSUC (80.9%) > CsMAL (66.2%) compared to other pharmaceutical compounds (salicylic acid, ibuprofen and ketoprofen). Desorption was achieved by using different eluants (either water or organic). The highest desorption ability was found for acetone (100% for CsTACON, CsSUC, CsMAL and 77% for CsITA) for all materials.

Microencapsulation of Fluticasone Propionate and Salmeterol Xinafoate in Modified Chitosan Microparticles for Release Optimization

“…decreases its folding ability, and thus, the crystal structure formation. Analogous results were found in our previous works on CS derivatives [31,32,35,44,46]. Following the above XRD analysis, TGA curves were recorded in order to examine the effect of the modifications on the thermal stability of chitosan.…”

“…Among the various methods of modification (carboxymethylation, thiolation, succinylation) [ 28 , 29 ], graft copolymerization has been the most applied by researchers, as it allows the formation of functional derivatives by covalent binding of a molecule onto chitosan matrix [ 30 ]. In particular, grafting of a polymer’s structure by adding carboxylic groups, i.e., trans-aconitic acid and succinic anhydride [ 31 , 32 , 33 , 34 ], or vinylic monomers, i.e., acrylic acid and 2-hydroxyethylacrylate ester [ 35 ] ( Figure 2 ) via radical polymerization, enhances its complexing capacity and results in improved swelling ratio, hydrophilicity and bacteriostatic characteristics, without affecting other significant properties. In fact, via radical polymerization, CS is grafted with short oligomeric chains, leading to derivatives with a short number of repetitive units.…”

Marine-Derived Polymeric Materials and Biomimetics: An Overview

“…Moreover, chitosan is non-toxic and can be biodegraded by lysozyme contained in human body fluids [38,39]. Owing to all these characteristics, chitosan is actively investigated and presents great potential in a multitude of applications including tissue engineering, drug delivery, wound dressing, scaffolds, pharmaceutical contaminant removal, cancer diagnosis, (nano)composites, high-tech materials, food, packaging, dye removal, and more [33,35,37,[40][41][42][43][44][45][46][47][48][49][50][51][52][53][54].…”

Design and Preparation of New Multifunctional Hydrogels Based on Chitosan/Acrylic Polymers for Drug Delivery and Wound Dressing Applications

“…It is known that the drug release from hydrogels is governed by several phenomena: diffusion, erosion, network relaxation, all in various proportions, depending on the polymer nature, network stability and parameters, morphology, hydrophilicity, the nature of the drug and its interaction with the matrix, the release medium etc., [ 37 , 38 , 39 , 40 ]. In order to study the drug release kinetics and mechanism, the drug release data were fitted into four models, using the following equations [ 21 , 41 , 42 , 43 ]: where Q t is the amount of drug released at time t, Q 0 is the original drug concentration in the material (40 mg), n is the release exponent and K is the release rate constant.…”