Abstract
Chitosan was modified with acetylacetone and ethylenediamine in the absence of solvent. The new biopolymer obtained from the modification was characterized by elemental analysis and NMR 13C and applied in the removal of diclofenac sodium aqueous solution varying the pH and time. Through elemental analysis was possible to verify a decreasing in C/N relation after reaction with acetylacetone and an increasing after modification with ethylenediamine. From NMR analysis was verified the appearance of peaks around 160-210 ppm in both materials due to free carbonyl groups in the first step of the modification, besides the formation of imine bonds. The adsorption tests showed that the highest value occurred at pH 4 and from the results of the kinetic study was found that maximum adsorption occurred within 45 minutes and experimental data adjusted better to linear adjustment, following pseudo second-order model. The results show a material efficient in the removal of emerging pollutants.
Highlights
The search for natural materials of low cost and renewable source has greatly increased and among these types of materials biopolymers has excelled
This reduction was due to the incorporation of acetylacetone in the structure of chitosan, with incorporation of carbon, hydrogen and oxygen, and a reduction of nitrogen, since in this molecule there is no availability of amino groups[13]
Chitosan modified with acetylacetone and ethylenediamine showed an increase in nitrogen to 5.66 mmol g–1 and an increase of carbon to 35.00 mmol g–1, causing an increase in C/N ratio of 6.13 to 6.18, compared to Cpure, due to incorporation of the ethylenediamine molecule containing two nitrogen, where one reacted with the carbonyl available of the molecule of acetylacetone, forming a new imine bond and the other staying in the form of –NH2
Summary
The search for natural materials of low cost and renewable source has greatly increased and among these types of materials biopolymers has excelled. Chitosan is a biopolymer obtained by deacetylation of chitin, which is the second most abundant biopolymer in nature and has been widely studied. The adsorption in biopolymers have been widely investigated, given that the industrial and population progressive growth has exposed the environment to various harmful substances such as pesticides, heavy metals, dyes, petroleum derivatives, pharmaceutical drugs, among others[4,5]. Concern about drug residues present in the aquatic environment is extremely important, since, they reaching water treatment plants can directly harm the population. This fact makes imperative the control and removal of these pharmaceuticals compounds from the aquatic environment, especially in the case of water for human consumption.
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