Adsorption of Anionic Dyes on the Biopolymer Chitin

Abstract

A adsorção dos corantes aniônicos alaranjado IV, alaranjado G e alaranjado de xilenol pela quitina foi estudada empregando a isoterma de Langmuir. Os parâmetros de adsorção foram determinados utilizando várias regressões lineares da isoterma. Os resultados revelaram que a capacidade de adsorção é dependente do pH. Em pH ácido, os grupos aminos do polímero estão protonados e a cadeia polimérica está carregada positivamente, predominando a adsorção por troca iônica. Deve ocorrer também em pequena extensão adsorção de van der Walls e por ligações de hidrogênio. Para o alaranjado de xilenol uma relação linear com coeficiente angular de 0,726 L mg -1 foi encontrada. O aumento da temperatura diminui a capacidade de adsorção pela quitina, devido ao aumento da etapa de desorção no mecanismo. Os valores de ∆H de -10,9 kJ mol -1 para o alaranjado G e -28,9 kJ mol -1 para o alaranjado IV comprovam uma adsorção de natureza física para estes corantes sobre a superfície da quitina.The adsorption of the anionic dyes orange IV, orange G and xylenol orange on chitin was studied, employing the Langmuir isotherm. The adsorption parameters were determined utilizing various linear regressions of the isotherm. The results showed that the adsorption capacity is dependent on pH. In acid pH, the polymer amino groups are protonated and the polymer chain is positively charged, with a predominance of adsorption through ion exchange. Van der Waals adsorption, as well as adsorption through hydrogen bonding, is also likely to occur to some extent. For xylenol orange, a linear regression was found, with an angular coefficient of 0.726 L mg -1 . The temperature increase reduces adsorption capacity by chitin, due to the enhancement of the desorption step in the mechanism. ∆H values of -10.9 kJ mol -1 for orange G and -28.9 kJ mol -1 for orange IV prove the physical nature of the adsorption by these dyes on the chitin surface.

Adsorptive removal of hazardous anionic dye “Congo red” from wastewater using waste materials and recovery by desorption

“…The water bodies and dependent flora and fauna are highly affected by these pollutants. Problems related with the water pollution include damage of the aesthetic nature of water, interference with the process of photosynthesis, destruction of the food web existing in water ecosystem [5], etc. The polluted water is also harmful to animals and human beings as the dyes and their metabolites are highly toxic [6,7] and carcinogenic [8,9] in nature.…”

Studies on the Removal of Cu(II) from Aqueous Solutions using Modified Acacia nilotica Leaf

“…The Langmuir isotherm (Eq. 2) can be linearized into the following form (Kinniburgh 1986;Longhinotti et al 1998…”

The Pre-concentration and determination of Iridium and Palladium in environmental water by imprinted polymer-based method

“…Analogs to the Langmuir isotherm are important for the description of the binding sites for the drugs and enzyme catalysis. Simple linear regression will result in different parameter estimations (Kinniburgh 1986;Longhinotti et al 1998). In addition, Langmuir types I, II, III and IV are used as more popular linear forms.…”