Adsorption of Industrial Pollutants by Natural and Modified Aluminosilicates

Abstract

The adsorption ability of natural clay minerals and zeolites is a structurally caused distinguished feature, which determines their physical-chemical properties and almost each area of application. The type of surface active sites responsible for adsorption behavior differs for various structural types of aluminosilicates and varies under modifying agents. The present chapter illustrates the effect of the acid and base modification of natural aluminosilicates on their adsorption behavior in respect to a number of pollutants present in aqueous media. For this, the change of adsorption-structural characteristics of natural clay samples containing representatives of the main groups of clay minerals under activation is considered. Further, the chapter focuses on characterization of surface active sites by means of a new method of a catalytic conversion of 2-methylbut-3-yn-2-ol. The presence of both acid and basic sites on the aluminosilicates surface as well as variations of surface acidity and basicity for different structural types of aluminosilicates under varying conditions of modification is discussed. The third highlight of the chapter encompasses adsorption processes taking place in aqueous solutions of formaldehyde, acetic acid, and ammonium chloride on the surface of natural and activated aluminosilicates. The activating effect of a number of inorganic acids and bases on adsorption equilibrium is compared. The considered mechanism of the adsorption of electrolytes and polar molecules from aqueous media may comprise hydrogen bonding, chemisorptions, or ion-exchange reactions.

Determinação da área superficial específica e da porosidade de duas amostras de argilas provenientes da bacia de Taubaté- São Paulo / Determination of specific surface area and porosity of two clays originated from Taubaté- Basin – São Paulo

“…Os mesoporos (poros de tamanho na faixa de 2-50 nm) são principalmente poros interpartículas e exercem influência menor do que os microporos na área superficial. Os microporos (poros de tamanho menor de 2 nm) podem se localizar nos espaçamentos intrapartícula nas regiões empilhadas "quasecristalinas" e no espaçamento intercamada parcialmente accessíveis ao adsorvato nas bordas das partículas de argilominerais expansíveis [5,8,[13][14][15][16] A área superficial específica dos aluminossilicatos é avaliada normalmente através dos dados fornecidos pelas isotermas de adsorção de nitrogênio (N2) a 77 K, as quais são obtidas como função da quantidade de N2 adsorvida em equilíbrio com a sua pressão ou concentração na fase gasosa, a temperatura constante [17]. Modelos clássicos utilizados para determinar a área superficial específica são: o modelo de Langmuir, desenvolvido para adsorção monocamada, e o modelo de Brunauer-Emmet-Teller [18] desenvolvido para adsorção em multicamadas Argilas apresentam valores de superfície específica entre 5 -200 m 2 /g [2,16].…”

Effect of activation temperature on surface basicity of natural aluminosilicates

“…H2O)(Al 3+ 2-yMg 2+ y)Si 4+ 4O10(OH)2 (1) Nontronite (M + y . H2O)Fe 3+ 2(Si x)O10(OH)2 (2) Smectites are widely demanded in most of industrial productions owing to their unique physical, chemical, mechanical, rheological and other properties, as well as their rich and spread natural deposits making them environmentally compatible and safe [4][5][6][7][8]. For operation with gases or volatile compounds [9,10] and, currently, by cement and concrete productions [11] to be used as a source of cementitious materials, raw clays need to be activated.…”

A case study of methomyl removal from aqueous solutions by four natural Albanian clays

“…Moreover, the type of interlayer material, such as water molecules, cations of alkali/alkaline earth metals, hydroxides, and so forth, are typical characteristics used for further classification of clays. Therefore, these structural characteristics in conjunction with their chemical composition determine the clay activity, which is expressed by the adsorption/exchangeability behavior (Novikova & Belchinskaya, 2016).…”