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Wpływ surfaktantów na właściwości adsorpcyjne substancji organicznych i jonów metali ciężkich w układach koloidalnych

Chibowski Stanisław, Wiśniewska Małgorzata

Wiadomości Chemiczne

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2021

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[Z] 75, 9-10

1181--1202

EN

The main purpose of this paper is description of the mechanisms governing the adsorption process of organic substances (such as polymers and dyes soluble in water) and inorganic substances (i.e. heavy metal ions) on the solid surface in the presence of synthetic surfactants of various ionic nature (anionic SDS, cationic CTAB and nonionic Triton X-100). The following polymers were applied: polyacrylamide, poly(ethylene glycol), poly(vinyl alcohol) and poly(acrylic acid). Moreover, the mono-, di- and triazo dyes with acidic, reactive and direct characters were used. Metal oxides – both simple (alumina, zirconia, titania) and mixed (double: silica-alumina, silica-titania and triple: alumina-silica-titania), as well as activated carbons obtained from biomass and peat were applied in the role of adsorbents. The effects of solution pH, ionic character of adsorbate, its molecular weight, elemental composition of the solid, its acid-base properties and textural structure, were determined. The understanding of the phenomena occuring at this type of interface is extremaly important for the effective control of colloidal suspensions stability, which is essential for practical applications. The formation of mixed adsorption layers composed of polymer-surfactant, dye-surfactant or polymer-surfactant-metal ion complexes results in many cases in a significant modification of the surface properties of solids, which is manifested not only by the changes in amount of bound adsorbate, but also by the changes in the structure of electrical double layer. The analysis of the obtained results indicated two main mechanisms of the surfactants influence on the adsorption process of organic and inorganic substances in colloidal systems containing a highly dispersed solid. The first one is the formation of polymer-surfactant, dye-surfactant or polymer-surfactant-metal complexes through both hydrophobic and electrostatic interactions, which show different affinity to the adsorbent surface. In most of the examined systems, these complexes were effectively bound at the solid-liquidinterface, which resulted in the adsorption increase of polymer, dye and heavy metal ions. The second important mechanism is the competition of surfactant molecules and other adsorbates for the active sites of the solid surface (the components of mixed adsorbates had the same ionic character). As a result of these two processes, mixed adsorption layers with a specific structure were formed, which determined the stability of the colloidal suspension.

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Adsorption of methylamine cations on kaolinite basal surfaces : A DFT study

Chen Jun, Min Fan-fei, Liu Ling-yun, Jia Fei-fei

Physicochemical Problems of Mineral Processing

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2020

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Vol. 56, iss. 2

338--349

EN

To explore the interaction of alkylamine surfactants with kaolinite, the density functional theory (DFT) method was used to calculate the single adsorption of different methylamine cation on kaolinite basal surfaces and the competitive adsorption of methylamine cation and water molecule on kaolinite basal surfaces, respectively. Different methylamine cations can adsorb on kaolinite basal surfaces by electrostatic interaction and hydrogen bonds, and the methylamine cations more easily adsorbed on kaolinite Si-O surface. In the case of competitive adsorption with water molecule, the methylamine cation is capable of flushing out the surrounding water molecule to get rid of its steric effect and stably adsorbing on kaolinite basal surfaces, and the adsorption state of the competitive adsorption system is more stable. The adsorption mechanism of methylamine cation on kaolinite basal surface should be the result of electrostatic interaction and hydrogen bonds, and the electrostatic interaction plays the main role.

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Adsorption behaviors of typical aromatic pollutants in biologically treated coking wastewater on powdered coal

Sun H., Wang Y., Bian Y., He X., Li G.

Physicochemical Problems of Mineral Processing

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2018

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Vol. 54, iss. 2

496--504

EN

The raw coal was utilized as adsorbent based on its remarkable adsorption ability of coal slime to organic compounds in the flotation process. This paper mainly investigates adsorption behaviors of benzpyrole (BZP), pyrrole (PR) and benzoic acid (BA) on powdered coal (PC). In the monocomponent solution, the removal efficiencies of BZP, PR and BA reached 85.23%, 55.02% and 24.84% at PC dosage of 20 g/dm3. Adsorption behaviors of three pollutants fitted perfectly to the pseudo-second order kinetics model and liquid film diffusion occupied the largest proportion in rate-limiting step according to the diffusion rates. Furthermore, the influences of pH on adsorption behaviors and competitive adsorption mechanism of three pollutants were also reported.