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1
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THE INFLUENCE OF SALINITY ON REACTIVE BLACK 5 DYE SORPTION EFFICIENCY ON HYDROGEL CHITOSAN SORBENTS

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Jóźwiak T., Filipkowska U., Bolozan L., Gache L.
Progress on Chemistry and Application of Chitin and its Derivatives
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2019
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vol. 24
49 - 60
EN
This study examined the effect of salt concentration (NaCl/Na2SO4) on the sorption efficiency of Reactive Black 5 (RB5) dye on chitosan hydrogel granules (CHs). The tested salt concentration was in the range of 0.0 to 0.5 mol/L. The scope of the research included the effect of salinity on RB5 sorption at different pH values (4–11), equilibrium time, and maximum sorption capacity (Langmuir 2 model). At low pH (pH 4, pHpHPZC), an opposite trend was observed (the sorption efficiency of RB5 on CHs increased with increasing salinity). The concentration of salt in the solution did not have a major impact on the equilibrium time of sorption, which depended mainly on the initial pH of the solution (and ranged from 36 to 60 h). The relatively long sorption time resulted from the hydrogel structure of the sorbent used, which slowed the dye absorption ability. The maximum sorption capacity of CHs in relation to RB5 at the optimum pH (pH 4) in the solution without the addition of salt determined after 60 h of sorption was 1.386 mmol RB5/g (1373.5 mg RB5/g). Under conditions of high salinity (0.5 mol Na2SO4/L), at pH 4, the capacity was 17.2% lower (1.148 mmol RB5/g to 1139.7 mg RB5/g), and at pH 11, it was 6.3% higher (1.474 mmol RB5/g to 1460.7 mg RB5/g).
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THE INFLUENCE OF CHITIN AMINATION ON THE EFFECTIVENESS OF RB5 AND RY84 DYE SORPTION

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Filipkowska U., Jóźwiak T., Bugajska P., Kuczajowska-Zadrożna M.
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vol. 23
66 - 75
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.
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APPLICATION OF CROSS-LINKED CHITOSAN FOR NITRATE NITROGEN (V) REMOVAL FROM AQUEOUS SOLUTIONS

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Jóźwiak T., Filipkowska U., Szymczyk P., Mielcarek A.
Progress on Chemistry and Application of Chitin and its Derivatives
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2014
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vol. 19
41-52
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.
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EFFECT OF CROSS-LINKING WITH GLUTARALDEHYDE ON ADSORPTION CAPACITY OF CHITOSAN BEADS

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Jóźwiak T., Filipkowska U., Rodziewicz J., Nowosad E.
Progress on Chemistry and Application of Chitin and its Derivatives
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2013
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vol. 18
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issue 18
35-47
EN
The study was undertaken to analyze the effect of chitosan cross-linking with glutaraldehyde on the adsorption capacity of chitosan beads during adsorption of Reactive Black (RB5) and Basic Green (BG4) dyes. Analyses were conducted at three pH values: pH 3.0; 5.0 and 9.0. Results obtained were evaluated with the use of four models of adsorption isotherms  Freundlich, Langmuir, Double Langmuir and Redlic-Petreson. The cross-linking of beads with glutaraldehyde turned out to be beneficial for the anionic dye RB5. Compared to the non-cross-linked beads, a comparable adsorption capacity (over 500 mg/g d.m.) was obtained at pH 3.0 and pH 5.0. In the case of the cationic dye, chitosan cross-linking reduced the quantity of adsorbed dye, irrespective of the pH value of the adsorption process.
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PHOSPHATE REMOVAL FROM AQUEOUS SOLUTIONS BY CHITIN AND CHITOSAN IN FLAKES

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Szymczyk P., Filipkowska U., Jóźwiak T., Kuczajowska-Zadrożna M.
Progress on Chemistry and Application of Chitin and its Derivatives
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2016
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vol. 21
192-202
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.
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THE USE OF ACTIVE CARBON IMMOBILISED ON CHITOSAN BEADS FOR RB5 AND BV10 DYE REMOVAL FROM AQUEOUS SOLUTIONS

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Filipkowska U., Jóźwiak T., Szymczyk P., Kuczajowska-Zadrożna M.
Progress on Chemistry and Application of Chitin and its Derivatives
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2017
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vol. 22
14-26
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.
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THE USE OF POLYSACCHARIDES FOR ACID RED 18 ANIONIC DYE REMOVAL FROM AQUEOUS SOLUTIONS

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Kuczajowska-Zadrożna M., Filipkowska U., Jóźwiak T., Szymczyk P.
Progress on Chemistry and Application of Chitin and its Derivatives
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2017
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vol. 22
106-117
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.
8
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APPLICATION OF CROSS-LINKED CHITOSAN FOR PHOSPHATE REMOVAL FROM AQUEOUS SOLUTIONS

100%
Filipkowska U., Jóźwiak T., Szymczyk P.
Progress on Chemistry and Application of Chitin and its Derivatives
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2014
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vol. 19
5-14
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.
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BIOSORPTION/DESORPTION OF CADMIUM(II) AND ZINC (II) FROM AQUEOUS SOLUTIONS BY ACTIVATED SLUDGE IMMOBILIZED ONTO CHITOSAN BEADS

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Kuczajowska-Zadrożna M., Filipkowska U., Jóźwiak T., Szymczyk P.
Progress on Chemistry and Application of Chitin and its Derivatives
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2015
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vol. 20
142-155
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.
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THE USE OF CHITIN AND CHITOSAN FOR THE REMOVAL OF REACTIVE BLACK 5 DYE

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Szymczyk P., Filipkowska U., Jóźwiak T., Kuczajowska-Zadrożna M.
Progress on Chemistry and Application of Chitin and its Derivatives
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2015
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vol. 20
260-272
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.
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USE OF SAWDUST IMMOBILISED ON CHITOSAN FOR DISPOSAL OF DYES FROM WATER SOLUTIONS

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Szymczyk P., Filipkowska U., Jóźwiak T., Kuczajowska-Zadrożna M.
Progress on Chemistry and Application of Chitin and its Derivatives
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2017
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vol. 22
207 - 219
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.
12
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THE INFLUENCE OF CHITOSAN CONTENT IN HYDROGEL BEADS ON THE SORPTION EFFECTIVENESS OF REACTIVE BLACK 5 DYE

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Filipkowska U., Jóźwiak T., Gache L., Bolozan L.
Progress on Chemistry and Application of Chitin and its Derivatives
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2019
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vol. 24
36 - 48
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.
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USE OF CHITOSAN ADSORBENTS FOR DYE REMOVAL IN THE AIR-LIFT REACTOR

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Filipkowska U., Jóźwiak T., Filipkowska M.
Progress on Chemistry and Application of Chitin and its Derivatives
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2022
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vol. 27
79-91
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.
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THE INFLUENCE OF CHITOSAN FLAKE DEACETYLATION DEGREE ON ORTHOPHOSPHATE SORPTION EFFICIENCY FROM AQUEOUS SOLUTIONS

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Bugajska P., Filipkowska U., Jóźwiak T., Kuczajowska-Zadrożna M.
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vol. 23
33 - 44
EN
The article presents the effectiveness of orthophosphate sorption from aqueous solutions depending on the deacetylation degree of chitosan flakes. The first stage of the research was to determine the pH value at which the sorption process was the most effective (from the pH range 2–11). In the second stage, research was carried out to determine the maximum sorption capacities of chitosan with deacetylation degrees of 75%, 85% and 90% in relation to PO43-. The highest effectiveness of orthophosphate removal on chitosan, regardless of its deacetylation degree, was obtained at pH 4. At pH 2 and 3, the chitosan flakes dissolved. This study showed that the sorption effectiveness of phosphorus compounds depends on the deacetylation degree of chitosan. Along with the increase in deacetylation degree, the sorption capacity of chitosan also increases in relation to orthophosphates. It is related to the higher number of amino groups in the structure of chitosan, which are responsible for the sorption of pollutants in the form of anions. The maximum sorption capacity of chitosan-DD = 75% in relation to biogen was 5.13 mg/g, chitosan-DD = 85% was 5.65 mg/g, and chitosan-DD = 90% was 5.91 mg/g. After 60 minutes, the desorption process had begun and was most likely caused by an increase in the pH of the solution. Due to chitosan's ability to neutralise the sample and the associated risk of desorption, the time of sorbent contact with sewage cannot be longer than 60 minutes.
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EFFECT OF IONIC AND COVALENT CROSSLINKING OF HYDROGEL CHITOSAN BEADS ON THE ADSORPTION EFFICIENCY OF BASIC VIOLET 10 AND BASIC GREEN 4 DYES FROM AQUEOUS SOLUTIONS

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Jóźwiak T., Filipkowska U., Filipkowska M.
Progress on Chemistry and Application of Chitin and its Derivatives
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2022
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vol. 27
116-134
EN
This work investigated the adsorption efficiency of Basic Violet 10 (BV10) and Basic Green 4 (BG4) dyes on ionically and covalently crosslinked chitosan hydrogel beads. The tested ionic crosslinkers were sodium citrate, sodium tripolyphosphate, and sulphosuccinic acid, while the covalent crosslinkers were glutaraldehyde, epichlorohydrin, and trimethylolpropane triglycidyl ether. The scope of the work included investigation of the effect of pH on the adsorption efficiency of dyes and the maximum adsorption capacity of crosslinked chitosan adsorbents. The maximum adsorption capacity of the non-crosslinked chitosan adsorbent was 2.94 mg/g and 44.32 mg/g for BV10 and BG4, respectively. Ionic crosslinking, regardless of the type of crosslinking agent, reduced the adsorption ability of hydrogel chitosan adsorbents in relation to cationic dyes (Qmax = 1.84-2.49 mg/g for BV10; 37.21-38.90 mg/g for BG4). Covalent crosslinking of chitosan slightly increased its adsorption capacity only for BV10 (Qmax = 3.59-3.81 mg/g for BV10; 39.15-40.62 mg/g for BG4).
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THE USE OF CHITIN IN THE MOULTS AND EXOSKELETONS OF MEALWORMS (TENEBRIO MOLITOR) TO REMOVE CATIONIC DYES FROM AQUEOUS SOLUTIONS

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Kurowska P., Jóźwiak T., Filipkowska U., Bakuła T.
Progress on Chemistry and Application of Chitin and its Derivatives
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2023
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vol. 28
56-74
EN
We analysed the feasibility of using unmodified chitin exoskeletons and moults of mealworms (Tenebrio molitor) as adsorbents to remove cationic dyes – Basic Violet 10 (BV10) and Basic Red 46 (BR46) – from aqueous solutions. We evaluated the characteristics of the adsorption materials using Fourier-transform infrared spectroscopy and determining the pH of the point of zero charge (pHPZC); the pH effect on dye adsorption effectiveness; dye adsorption kinetics (pseudo–first order, pseudo–second order, and intramolecular diffusion models); and the maximum adsorption capacity of the adsorbents (Langmuir 1 and 2 and Freundlich isotherms). BV10 adsorption on the tested adsorbents was the highest at pH 3, while adsorption of BR46 was highest at pH 6. The adsorption equilibrium time depended mainly on the dye type and its initial concentration; it was 150–210 min for BV10 and 120–150 min for BR46. The maximum adsorption capacity of mealworm exoskeletons reached 5.56 mg/g for BV10 and 31.53 mg/g for BR46, whereas mealworm moults exhibited a higher maximum adsorption capacity, reaching 6.44 mg/g for BV10 and 5.56 mg/g for BR46.
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CYCLICAL METAL ADSORPTION AND DESORPTION THROUGH SLUDGE IMMOBILIZED IN CHITOSAN MEDIA

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Kuczajowska-Zadrożna M., Filipkowska U., Jóźwiak T., Szymczyk P.
Progress on Chemistry and Application of Chitin and its Derivatives
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2016
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vol. 21
135-146
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.
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REMOVAL OF DYES FROM AQUEOUS SOLUTIONS BY GLAUCONITE IMMOBILISED ON CHITOSAN HYDROGEL BEADS

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Jóźwiak T., Filipkowska U., Szymczyk P., Kuczajowska-Zadrożna M., Mielcarek A.
Progress on Chemistry and Application of Chitin and its Derivatives
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2017
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vol. 22
54-65
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.
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THE INFLUENCE OF THE DEACETYLATION DEGREE OF CHITOSAN IN THE FORM OF FLAKES ON THE EFFECTIVENESS OF NITRATES V SORPTION FROM AQUEOUS SOLUTIONS

88%
Jóźwiak T., Filipkowska U., Bugajska P., Kuczajowska-Zadrożna M., Mielcarek A.
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vol. 23
88 - 96
EN
The influence of the degree of deacetylation of chitosan from the range of DD = 75–90% on the effectiveness of sorption of nitrates from aqueous solutions was investigated. The scope of the research included: determining the effect of pH on the effectiveness of N-NO3 binding on chitosan sorbents and determining the sorption capacity of chitosan sorbents with different degrees of deacetylation after 5, 15, 30 and 60 minutes. The effectiveness of sorption of nitrates on chitosan sorbents increased in the series DD=75% < DD=85% < DD=90%. Regardless of the degree of deacetylation, the sorption effectiveness of nitrates on chitosan was the highest at pH 4. The amount of nitrate-related sorbents was the highest after 30 min of sorption. A process time which was too long resulted in desorption of nitrates. The maximum sorption capacity for chitosan with the degree of deacetylation DD = 75, 85 and 90% was 0.59 mg N-NO3/g, 0.60 mg N-NO3/g and 0.87 mg N-NO3/g, respectively.
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APPLICATION OF CHITOSAN IONICALLY CROSSLINKED WITH SODIUM EDETATE FOR REACTIVE DYES REMOVAL FROM AQUEOUS SOLUTIONS

88%
Jóźwiak T., Filipkowska U., Szymczyk P., Kuczajowska-Zadrożna M., Mielcarek A.
Progress on Chemistry and Application of Chitin and its Derivatives
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2015
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vol. 20
82-96
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.
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