Performance of oxalic acid-chitosan/alumina ceramic biocomposite for the adsorption of a reactive anionic azo dye

Abstract

A biocomposite system was developed and tested for the removal of the azo dye Reative Red (RR195) from wastewater. The biocomposite was synthesized using ceramic particles containing 75% alumina which were coated using chitosan crosslinked with oxalic acid. The biocomposite showed high performance at low pH (maximum adsorption capacity= 345.3mg.g -1 at pH=2). The physico-chemical and structure characteristics of the matrix were evaluated by Z-potential, FTIR-ATR, SEM-EDS, DRX and porosity. Langmuir sorption isotherm and Pseudo Second order model gave the best fit. The electrostatic interaction between RR195 (due to the sulfonate groups) and the free amino groups of chitosan, enabled successive desorption/regeneration cycles. The maximum removal percentage (>80%) occurred at pH=2 due to the crosslinking effect. Experiments at different temperatures allowed the calculation of thermodynamic parameters (G, S, H); adsorption was spontaneous, exothermic and enthalpy controlled. The presence of inorganic ions (NO3 ->Cl -) was analyzed during the adsorption process. This novel biocomposite can be applied as a cost-effective and environmentally friendly adsorbent for anionic azo dye removal from wastewater. The application of chitosan crosslinked with oxalic acid as a coating of the ceramic support enhanced the adsorption capacity and enabled its use under acidic conditions without solubilization.

Study on the adsorption properties of multiple-generation hyperbranched collagen fibers towards isolan-series acid dyes

“…The pH of the solution influences the protonation degree of the adsorbent, thereby determining the specific charge of the binding sites and the adsorption performance of the adsorbent. 28 The CF-HBPN-II contains amino (p K a ) groups. When the pH was lesser than p K a , the cationic form was dominated.…”

Experimental study and modelling of an azo colourant dynamic adsorption onto functional cross‐linked chitosan/ceramic particles in a fixed bed column

“…The FTIR-ATR spectrum of AOCh is shown in Figure S1D, demonstrating the ionic cross-linking of Ch by the OA action due to the two important bands observed: (a) the wavenumber shift of the band of the symmetric stretching of the carboxylic group of the OA from 1698 to 1685 cm À1 for AOCh [32] and (b) the shift and deformation in the band of the amino group (1517 cm À1 ) due to the ionic interaction of the protonated amino group from Ch with the carboxyl anions of the OA; for the case of the unmodified Ch, this band is presented at 1550 cm À1 . [16,24,31] OA is a dicarboxylic acid that was used to bind the alumina from CerPe and Ch; this is due to the esterification reaction between one of the carboxylate anions ( RCO 2 À ) of OA and alumina generating the alumina (III) oxalate complex. The presence of the ester bond was verified by the appearance of a band at 1723 cm À1 in the AOCh spectrum (Figure S1D); this band is characteristic of the C O tension of the ester group.…”

“…A complete description of the composite material AOCh used to fill the fixed bed column was previously reported. [24] 3.2 | Effect of operating conditions on the dynamic sorption using fixed-bed column Dynamic adsorption tests were evaluated taking into account different parameters such as bed depth (Z), influent concentration (C 0 ), and volumetric flow rate (F); the measurements were carried out at pH = 2.0 in all cases, based on previous batch tests in which it was found that the novel material presents at this pH its maximum adsorption performance maintaining excellent physical properties. [24] The obtained breakthrough curves are shown in Figure 2.…”

“…[24] 3.2 | Effect of operating conditions on the dynamic sorption using fixed-bed column Dynamic adsorption tests were evaluated taking into account different parameters such as bed depth (Z), influent concentration (C 0 ), and volumetric flow rate (F); the measurements were carried out at pH = 2.0 in all cases, based on previous batch tests in which it was found that the novel material presents at this pH its maximum adsorption performance maintaining excellent physical properties. [24] The obtained breakthrough curves are shown in Figure 2. The region where the most important concentration change occurs in the column is the mass transfer zone (MTZ), which separates the active zone of the AOCh from the saturation zone.…”

“…[17,18] In order to improve the mechanical stability of the sorbent material, different Ch/alumina biocomposites have been reported for the removal of different pollutants such as chromium, [19,20] nitrate, [21] fluorine, [22] and azo dyes. [23,24] Fixed bed columns are very convenient to remove pollutants under continuous operating conditions. In this case, an economical, eco-compatible, and stable (chemically and physically) material with high mechanical strength is required.…”