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Modelling equilibrium data for manganese(II) sorption onto manganese dioxide modified chalcedonite using the non-linear regression method

100%
Michel M. M., Kiedrynska L.
Annals of Warsaw University of Life Sciences - SGGW. Land Reclamation
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2011
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tom 43
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nr 2
2

Evaluation of adsorption parameters and charge densities of some selected soils: application to lead

100%
Diatta J. B.
Electronic Journal of Polish Agricultural Universities. Series Environmental Development
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2002
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tom 05
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nr 2
An attempt to evaluate adsorption parameters and charge-based densities for Pb is reported in the paper. The method was based on the calculation of Langmuir adsorption maximum (amax), and the bonding energy term (b). The parameters were the outcome of well-established linear relationships of Ce/S versus Ce (Ce, equilibrium concentration and S, amount adsorbed). The use of charge-based sorption density parameter (SDCEC), which expressed the number of accessible charges for Pb adsorption, evidenced the occurrence of two main adsorption phases, characterised by two different slopes. The first ones, varying from 0.536 to 3.144 were suggested to be attributed to ‘high attractive sites’, whereas the second with slopes from 0.011 to 0.259, probably represented ‘low attractive sites.
3

The effect of poly[vinyl alcohol] on cadmium adsorption and desorption from alginate adsorbents

67%
Klimiuk E., Kuczajowska-Zadrozna M.
Polish Journal of Environmental Studies
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2002
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tom 11
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nr 4
Cadmium adsorption onto and desorption from sodium alginate and sodium alginate with poly(vinyl alcohol) (PVA) were studied. Intraparticular diffusion was demonstrated to limit adsorption kinetics during the first 20 min of process. The Deff value was dependent on adsorbent chemical composition and ranged from 3.35 ´ 10-10 m2/s to 1.86 ´ 10-10 m2/s for the 1.5% alginate with 0.5% PVA and for the 2% alginate with 5% PVA, respectively. At equilibrium the adsorption was more effective onto the 2% alginate and was lower for the alginate sorbent containing poly(vinyl alcohol). The dimensionless separation factor RL increased from 0.26 to 0.68 for the 2% alginate and the 2% alginate + 5% PVA, respectively. The maximum adsorption capacities in Langmuir isotherm for both the 2% and 1.5% alginate with 0.5% PVA were similar and were 176 and 178 mg/g dry weight, respectively. However, the adsorption capacity decreased to 48 mg/g dry weight for the 2% alginate with the 5% PVA (in proportion to the polymer amount increase in the adsorbent). Cadmium desorption was more effective for nitric acid than for sulfuric and hydrochloric acids (desorption pH 2.2). More cadmium was desorbed from 2% alginate with 5% PVA than from 2% alginate or 1.5% alginate with 0.5% PVA.
4

The effect of pH and chitin preparation on adsorption of reactive dyes

67%
Klimiuk E., Filipkowska U., Wojtasz-Pajak A.
Polish Journal of Environmental Studies
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2003
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tom 12
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nr 5
The effect of chitin preparation with HCl (chitin A) and with HCl and KOH (chitin B) and pH on the adsorption of reactive dyes (helactine, polactine and remazol) on chitin was investigated. The double Lang- muir equation was appropriate to analyze the dependence between amount of the adsorbed dye on chitin (Q) and its equilibrium concentration (C). It indicated the presence of two types of active sites which differed in both the maximum adsorption capacity (b) and adsorption affinity (K). Based on the dimensionless separa­tion factor R it was found that the dye adsorption mechanism in type I sites was an ion exchange, whereas in the case of type II sites it was a physical adsorption. The adsorption capacity of the chitin A (deacetylation degree of 3%) for samples without pH adjustment ranged from 29 (Red D-8B) to 67 mg/g dry weight of chitin (Gelb GR). At pH 3.0 the adsorption capacity was higher from 1.9 to 2.3-fold. The most favourable effect of pH change was found for helactine dyes. The adsorption capacity of the chitin B (deacetylation degree of 5%) was from 66 (Brillantorange 3R) to 101 mg/g dry weight of chitin (Gelb GR). After pH adjustment to pH 3.0 the adsorption capacity ranged from 160 (Ruby F-2B) to 294 mg/g dry weight of chitin (Blau 3R). The most favourable effect of deacety- lation degree increase was found in the case of helactine dyes in the samples without pH adjustment, and polactine and remazol dyes at pH 3.0.
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Adsorption of reactive dyes by modified chitin from aqueous solutions

67%
Filipkowska U., Klimiuk E., Grabowski S., Siedlecka E.
Polish Journal of Environmental Studies
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2002
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tom 11
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nr 4
The adsorption of reactive dyes onto chitin (deacetylation degree = 5%) was investigated from aqueous solutions at pH 3. Ten reactive dyes were examined, including 5 dyes from the helactine group, 3 dyes from the polactine group and 2 dyes from the remazol group. The K and b constants were calculated from the Langmuir equation that assumes the presence of two sites of different nature. It was found that the dye adsorption on chitin in type I and II sites differed in both the adsorption affinity and maximum adsorption capacity. Based on the dimensionless separation factor RL it was found that the dye adsorption mechanism in type I sites was an ion exchange, whereas in the case of type II sites it was a physical adsorption. A correlation was found between dye adsorption on chitin and the number of sulfone groups in a dye molecule. However, neither molecular weight nor the number of aromatic rings was correlated with dye adsorption.
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