Influence of Different Factors on the Sorption of Metals (Co 2+ and Ni 2+ ) by Modified Sodium Humate
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uence of Different Factors on the Sorption of Metals (Co2+ and Ni2+) by Modified Sodium Humate U. Zh. Dzhusipbekova,*, G. O. Nurgalievaa,*, A. K. Shakirovaa,**, Z. K. Bayakhmetovaa,*, and A. S. Taubaevaa,* a
Bekturov Institute of Chemical Sciences, Almaty, 050010 Kazakhstan *е-mail: [email protected] **е-mail: [email protected]
Received October 14, 2019; revised November 15, 2019; accepted March 30, 2020
Abstract—The sorption properties of a modified ethylenediamine humate (EDA–H) sorbent toward Co2+ and Ni2+ metal ions are considered. The results of the influence of sorbent norm (0.05–2.0 g), process time (15–120 min), and metal concentration (0.005, 0.05, and 0.5 g/L) are presented. The advanced extraction of cobalt(II) in solutions with low and medium metal concentrations (0.005–0.05 g/L) and nickel(II) in solutions with a high concentration of cations (0.5 g/L) were detected. Based on the data of physicochemical analysis, it can be assumed that complexation with the sorbent occurred in the course of Co(II) and Ni(II) metal sorption by the sorbent. Keywords: humic substances, sorption, modified sorbent, cobalt and nickel ions DOI: 10.3103/S0361521920040047
Humic substances are natural organic compounds, which contain from 50 to 90% organic matter of peat and coals; they are mixtures of complex high-molecular-weight substances with various functional groups. Humic substances are environmentally friendly, nontoxic, and cheap organic compounds of natural origin with sorption properties [1, 2]. Due to their chemical structure, humic substances can undergo chemical modification to provide the ability to form stable complexes with heavy metal cations [3]. Chemical modification, after which existing properties are improved and new ones appear, is an effective method to develop new sorbents based on humic compounds. Methods for the methylation of humic substances were described in the literature. The modification was carried out using methylating agents: diazomethane [4, 5] and methyl iodide in the presence of silver oxide, methanol in the presence of HCl or BF3 [6], and dimethyl sulfate [7]. Both phenolic hydroxyls and carboxyl groups were methylated with the use of diazomethane in an ether solution. The concentrations of carboxyl, phenol, and alcohol groups in the structure of humic substances were determined by varying methylation methods and the subsequent processing of the derivative. Methylation experiments with dimethyl sulfate, which led to the modification of phenolic and alcohol groups in humic substances, were carried out [8, 9]. In methylation with methanol, a reaction occurred at their carboxyl groups.
Humic substances were modified by trimethylsilylation followed by the measurement and processing of 29Si NMR spectra [10]. According to experimental data, the trimethylsilylation reaction of humic substances proceeds with the replacement of protons in various functional groups (–OH, =NH, –NH2, –SH, and –COOH) by the silyl group. This leads to disintegration of humic substances. The modification of humic s
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