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EN
This study was aimed at determining the possibility of applying non-cross-linked chitosan (CHs) as well as chitosan cross-linked with glutaraldehyde (CHs-GLA) and epichlorohydrin (CHSECH) for the removal of nitrates (V) from aqueous solutions. The scope of the study included determinations of: optimal pH value of nitrates sorption (from pH range of 2-11), equilibrium time of sorption process, and maximum N-NO3 sorption capacity of the analysed chitosan sorbents. Kinetics of nitrates sorption was described with pseudo-first and pseudo-second order equations, and with the intraparticle diffusion model. Sorption capacity analysis was conducted with the heterogeneous Langmuir model, the double Langmuir model and the Freundlich model. The optimal pH value of N-NO3 sorption onto CHs-GLA and CHs-ECH was pH 3, whereas onto CHs this was pH 4. The equilibrium time of sorption reaction was the same for all chitosan sorbents and reached 120 min. The maximum sorption capacity of CHs, CHs-GLA and CHs- ECH accounted for 12.71 mg N-NO3/g, 34.99 mg N-NO3/g and 38.47 mg N-NO3/g.
EN
The article presents the effectiveness of phosphate adsorption on the flakes of chitin and chitosan. Studies performed determined adsorption capacity of chitin and chitosan, best among the tested adsorption pH and the equilibrium time. Langmuir model was used to describe the results. The highest removal efficiency of phosphorus compounds using chitin was obtained at pH 3 and with chitosan at pH 4. The study of phosphate equilibrium concentration time obtained for both sorbents was carried out at three concentrations of 1, 5 and 10 mg/dm3. The highest sorption efficiency of the phosphate using chitin was achieved after 20 minutes of the process and at the chitosan after 40 minutes. In the case of chitosan after the equilibrium time the effect of partial P-PO4 release was observed, which could be related to the change in pH of the solution by the sorbent. Studies have shown that chitosan is a more effective absorbent for phosphorus compounds. The maximum adsorption capacity of chitosan with phosphate was 6.65 mg/g, and chitin - 2.09 mg/g.
EN
This paper presents the adsorption of dyes – the anionic Reactive Black 5 (RB5) and cationic Basic Violet 10 (BV10) dyes – on activated carbon (AC) immobilised on chitosan (CHs). The results were compared with the removal efficiency of RB5 and BV10 on the individual sorbents: chitosan beads and activated carbon. In this study, the sorption capacities of the sorbents, sorption pH and the point of zero charge (pHZPC) were determined. For the description of the obtained results, the Freundlich, Langmuir and double Langmuir models were used. The results show that the developed sorbent (CHs-AC) is effective for both types of dye (RB5 or BV10) over a broad pH range 4–10, which makes it a universal sorbent. The maximum sorption capacity of CHs-AC with RB5 was 639.8 mg/g, while for BV10 it was 50.7 mg/g.
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.
EN
This study investigated the effectiveness of phosphate adsorption onto non-cross-linked chitosan beads [CHs], and onto chitosan beads cross-linked with glutaraldehyde [ALD-CHs] and epichlorohydrin [ECH-CHs]. The weight ratio of glutaraldehyde to chitosan was 1:2 (w/w), whereas that of epichlorohydrin to chitosan was 2:1 (w/w). The optimal pH value of the phosphate adsorption process was determined at pH 3 for cross-linked chitosan and at pH 4 for noncross- linked chitosan. The time needed to reach the equilibrium concentration reached 60 min for both adsorbents. Experimental data were described with the heterogeneous Langmuir model (double Langmuir equation). The most effective adsorbent of phosphates was shown to be chitosan cross-linked with epichlorohydrin [ECH-CHs] - for which the adsorption capacity reached 139.4 mg/g d.m.CHs. In the case of the remaining adsorbents (chitosan [CHs] and chitosan crosslinked with glutaraldehyde [ALD-CHs]) the adsorption capacity was lower and accounted for 44.38 mg/g d.m.CHs and 108.24 mg/g d.m.CHs, respectively.
EN
In this study, we evaluated the effectiveness of cadmium and zinc adsorption and desorption from solutions containing single metals and a mixture of metals in the ratio of 1:2 by activated sludge immobilized onto chitosan (ASC). The optimal pH value determined for metals adsorption ranged from pH 5 to pH 6, whereas that established for desorption reached pH 2. In the case of individual metals, the state of adsorption equilibrium in the solution was achieved after 180 min, whereas in the case of a metal mixture – after 270 min. In the case of desorption, the state of equilibrium was achieved after 45 min. It was stated that both adsorption and desorption proceeded according to the pseudo-second order reaction. The study enabled determining the maximum adsorption capacity based on Langmuir, Freundlich and Sips models. The Sips model was found suitable for the description of adsorption of single metals onto ASC, whereas both Sips and Freundlich models – for description of the adsorption of a metal mixture, which was indicated by the determined values of R2 coefficient. The adsorption capacity of ASC determined from Sips model for individual solutions of cadmium and zinc reached 216 and 188.3 mg/g d.m., respectively, whereas that determined for their mixture reached 106 mg/g d.m. for both metals.
EN
In this study, we investigated the effectiveness of Reactive Black 5 dye adsorption onto chitin and chitosan flakes. Adsorption capacity of chitin and chitosan, optimal pH of the adsorption process and reaction equilibrium time were determined. Results achieved were described with Freundlich, Langmuir and double Langmuir models. The pH value ensuring the highest dye adsorption effectiveness onto chitosan was pH 4. In turn, the highest dye adsorption effectiveness onto chitin was determined at pH 2, however considering that the pH value of industrial wastewater containing reactive dyes ranges from pH 3 to pH 4, further analyses with chitin were continued at pH 3. The time needed to reach the equilibrium concentration of dye was 360 min for chitin and 72 hours for chitosan. The study demonstrated that chitosan is the most effective sorbent of RB5. Its maximum adsorption capacity of the reactive dye accounted for 696.99 mg/g d.m., compared to 131.56 mg/g d.m. determined for chitin. Higher effectiveness of RB5 removal by chitosan is result of more number of amine groups in the chemical structure of this polymer, compared to chitin.
EN
In this article, the sorption properties of chitosan hydrogel beads, beech sawdust and sawdust immobilised on chitosan in relation to Reactive Black 5 (RB5) and Basic Violet 10 (BV10) dyes were compared. In the conducted research, the sorption capacities of the sorbents, sorption pH and the point of zero charge (pHZPC) were determined. For the description of the obtained results, the double Langmuir model has been used. The highest effectiveness of the cationic and anionic dye removal on chitosan hydrogel beads and sawdust immobilised on chitosan was obtained at pH 4, whereas on sawdust, the pH was 3. The best sorbent in relation to the RB5 dye was obtained using chitosan hydrogel beads, and in relation to BV10, it was sawdust. The maximum sorption capacity of chitosan in relation to RB5 was 875.66 mg/g, whereas the sorption capacity of sawdust in relation to BV10 was 30.15 mg/g. The research has shown that the sorbent in the form of sawdust immobilised on chitosan had a high sorption capacity in relation to anionic as well as cationic dyes. Immobilisation of sawdust on chitosan led to the creation of a universal sorbent in relation to cationic and anionic dyes.
EN
In this research, a cyclical adsorption/desorption of cadmium and zinc from solutions containing a single metal or its mixture in ratio of 1:1 and 1:2 using immobilized activated sludge in the chitosan (ASC) was examined. In the adsorption studies, the optimal dose of ASC was 4 g/L. The highest desorption efficiency was achieved for 1M HNO3. Both adsorption and desorption occurred in accordance with a pseudo-second order reactions which is confirmed by R2 values. Mass of zinc adsorbed and desorbed in one cycle from a solution containing a single metal was 0.78 and 0.40 mmol/g d.w. when cadmium was lower (respectively 0.41 and 0.21 mmol/g d.w.). In subsequent cycles, both metals were adsorbed and desorbed at a lower efficiency. The highest efficiency of desorption was observed for a mixture of Cd:Zn in the ratio of 1:1 and 1:2, respectively 86% and 89% of cycle1, whereas for the zinc it was 70% and 53%. Desorption efficiency of both metals and its mixtures, in subsequent cycles gradually decreased.
EN
The sorption capacity of glauconite, glauconite immobilised on chitosan hydrogel beads and unmodified chitosan hydrogel beads against Reactive Black 5 and Basic Violet 10 was compared in this article. The effect of pH on the sorption effectiveness of dyes on the tested sorbents was investigated and the sorption capacity of sorbents after 24 and 72 h was determined. Langmuir sorption, double Langmuir and Freundlich isotherms were used to describe the experimental data. The adsorption efficiency of the dyes on sorbents containing chitosan was highest at pH 4. In the case of glauconite, Reactive Black 5 removal efficiency was the highest at pH 3, and Basic Violet 10 removal efficiency was highest at pH 2. The sorption capacity of glauconite immobilised on chitosan hydrogel spheres obtained after 72 h was -656.73 mg/g and -32.77 mg/g for Reactive Black 5 and Basic Violet 10, respectively.
EN
In this study, we investigated the effect of chitosan crosslinking with sodium edetate (SE) on its sorption capacity of Reactive Black 5 and Reactive Yellow 84 dyes. The first stage of the study allowed establishing conditions of chitosan crosslinking. The process of ionic crosslinking was effective only at pH 4 and at the optimal dose of sodium edetate ranging from 0.046 to 0.462 g/g CHs. Process temperature in the range of 20-60oC had no significant effect on the stability of crosslinked chitosan. Contrary to the non-crosslinked chitosan (CHs), chitosan crosslinked with sodium edetate (CHs-SE) was capable of dyes sorption at pH 3. Sorption of reactive onto both CHs and CHs-SE was the most effective at pH 4. Chitosan crosslinking with SE had a positive effect on the effectiveness of RB5 and RY84 sorption. This effect was especially tangible within the first ten or so hours of sorption. After 24 h of the process, the sorption capacity of CHs-SE against RB5 and RY84 reached 1296.69 mg/g and 1883.62 mg/g, respectively. In the case of CHs, sorption capacity achieved after the same time was lower and accounted for 1025.55 mg RB5/g and 1539.67 mg RY84/g.
EN
In this work, the effect of cross-linking of chitosan beads on the removal efficiency of dye RB 5 from aqueous solutions was defined. In the studies not crosslinked chitosan as well as chitosan cross-linked with a chemical cross-linking agent - glutaraldehyde and ionic cross-linking agent - pentasodium tripolyphosphate were used. The scope of the research included the determination of pH at which the adsorption process proceeded efficiently, study time, in order to designate the time, after which the reaction equilibrium is reached and to determine the kinetics of the adsorption process and constants in the Langmuir 2 equation. The work sets maximum sorption capacity of the sorbent non-crosslinked and two crosslinked sorbents. Based on these results, it was found that the highest removal efficiency of dye RB 5 was obtained for chitosan crosslinked with ion agent - pentasodium tripolyphosphate. The maximum sorption capacity of the sorbent amounted 1125.7 mg / g d.m. of chitosan.
EN
The present study investigated the sorption of Basic Yellow 28 (BY 28) and Acid Yellow 23 (AY 23) by chitin flakes. The study determined the influence of pH value on adsorption effectiveness and the adsorption capacity of chitin flakes. The results were described with Freundlich, Langmuir, Sips and double Langmuir isotherms. Similar values of adsorption capacities were achieved for both tested dyes using Langmuir, Sips and Langmuir2 models, i.e. 16.804, 17.740 and 18687 mg/g d.m. for BY28 as well as 24.195, 27.930 and 24.196 mg/g d.m. for AY23, respectively. The isotherms were compared with the use of average relative error (ARE) of approximation. In the case of both dyes, the best fit to experimental data was achieved with the use of tri-parametric Sips equilibrium isotherm, which was indicated by ARE values of 3.10% (BY 28) and 5.26% (AY 23).
EN
In the paper sorption capacity of chitosan having a deacetylation degree DD=75%, DD=85% and DD=90% relatively to the Reactive Black 5 were compared. Studies on the effectiveness of the dye sorption were carried out in a wide pH range – from 3 to 11. For each of the tested chitosan sorbents, sorption capacity has been determined. The results were described by isotherms Freundlich and Lagmuir isotherms, and a double Langmuir isotherm. Sorption of Reactive Black 5 most efficiently occurred at pH 4. At pH <4 chitosan sorbents underwent dissolution, regardless of the degree of deacetylation. The efficiency of dye sorption increased with the degree of deacetylation. The sorption capacity calculated after 12 h of the chitosan sorption with DD=75%, DD=85% and DD =90% was, relatively to the Reactive Black 5, respectively 433.03 mg/g and 464.52 mg/g and 532.14 mg/g. The impact of the deacetylation degree on pHZPC (zero point of charge) of the sorbent was also examined. Along with the increase in the deacetylation degree the value of chitosan pHZPC increased as well and at DD=75% DD=85% and DD=90%, pHZPC amounted respectively 7.6, 7.7 and 7.8.
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