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EN
Adsorption tests in the air-lift reactor were carried out for six dyes – four anionic (RR11, RB5, RB8, and RR18) and two cationic (BV10 and BG 4) – as well as three adsorbents – chitosan flakes, chitosan in the form of beads, and modified sawdust immobilised in chitosan (adsorbent 3). The dye concentration in the inflow to the reactor in all the conducted test series was 10 mg/dm3; the amount of adsorbent was also constant at 10 g dry matter (d.m./dm3, and the flow rate was 0.1 V/h. For all tested dyes, the obtained maximum adsorption capacity was high and ranged from 3802 to 2203 mg/g d.m. for chitosan flakes, from 3312 to 2076 mg/g d.m. for chitosan beads, and from 2734 to 2148 mg/g d.m. for modified sawdust immobilised in chitosan. The immobilisation of sawdust on chitosan resulted in effective adsorption of both anionic and cationic dyes.
EN
This article presents the influence of chitin amination on the effectiveness of RB5 and RY84 dye sorption. For chitin and chitin modified by amination, the optimal pH of sorption and the maximum sorption capacity were determined in relation to two reactive dyes: Reactive Black 5 (RB5) and Reactive Yellow 84 (RY84), differing in the active group and molecular weight. Three sorption models were used to describe the experimental data: Langmuir, Langmuir 2 and Freundlich. The highest sorption capacity was obtained for aminated chitin for both tested dyes: 386.53 mg/g for RB5 and 261.56 mg/g for RY84. In the case of sorption on unmodified chitin, the sorption capacities were lower: up to 235.65 mg/g.d.m. for RB5 and 208.88 mg/g.d.m. for RY84. The modification of chitin by amination has a beneficial effect on the amount of dye adsorbed in the process. The adsorptive capacity increased by 1.6-times in the case of RB5 and 1.25-times in case of RY84.
EN
Here, we report the fabrication of supermacroporous monolith sorbents for acidic dye removal via chitosan cross-linking with ethylene glycol diglycidyl ether (EGDGE) in acidic medium at sub-zero temperature. The developed porous structure with the thickness of polymer walls in the range of a few microns and a high content of primary amino groups determined the high sorption capacity of the sorbents toward Alizarin Red in a broad pH range (2–8). Due to the cross-linking via hydroxyl groups of the chitosan, the static sorption capacity of the fabricated materials was higher than that of chitosan flakes, even for sorbents cross-linked at EGDGE:NH2-chitosan with molar ratio 2:1. The monolith sorbents were mechanically stable and supported flow rates up to 300 bed volumes per hour. The breakthrough curve of Alizarin Red sorption showed that the effective dynamic sorption capacity was 283 mg/g, and 100% of the dye could be removed from the solutions with concentration of 100 mg/L. The monoliths can be regenerated with 0.3s M NaOH solution and used in several consecutive cycles of sorption/regeneration without loss of efficacy.
EN
The influence of chitosan content in hydrogel beads on the sorption effectiveness of Reactive Black 5 (RB5) dye from aqueous solutions is presented in the following work. The dry mass of chitosan in the tested hydrogel chitosan sorbents was from 2 to 10%. The influence of pH (4–11) on the sorption effectiveness of RB5 on chitosan hydrogels as well as the sorption capacity of the tested chitosan sorbents in relation to RB5 were studied. The optimal pH of RB5 sorption was determined along with the pH at the potential at zero point charge (pHPZC) of the tested sorbents. The maximum sorption capacity of the tested sorbents, depending on the amount of chitosan dry mass in the hydrogel beads, was determined. The obtained data was fit to Langmuir 1, Langmuir 2, and Freundlich models.
EN
In the paper, the adsorption of Acid Red 18 (AR18) on chitosan (CHs), sodium carboxymethyl cellulose (CMC) and agar (AGA) was researched. The adsorption capability of biosorbents was examined as a function of initial pH, time of contact and influence of initial concentration of dye. The adsorption kinetics was compared with the pseudo 1. and 2. order models. It was found that the dye adsorption occurred in accordance with the pseudo 2. order model. The experimental data of adsorption in the equilibrium state was analysed with the use of isotherms of the Freundlich, Langmuir and double-Langmuir models. It was found that for the description of dye adsorption on adsorbents, the double-Langmuir model was suitable, which was demonstrated by the determined values of the average relative error (ARE). The highest adsorption capacity and affinity to AR 18 was obtained for CHs, at 81.7 mg/g d.w and 0.997 L/mg, respectively. The experimental results show that CHs seems to be a promising biosorbent for AR 18 dye removal from aqueous solutions.
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