Površinska modifikacija zeolita i uticaj pH i jonske jačine na desorpciju amina

Abstract

Ispitivan je uticaj temperature na adsorpciju stearildimetilbenzil-amonijum-hlorida (SDBAH ) na prirodnom zeolitskom tufu. Maksimalna adsorbovana količina SDBAH iznosila je 123 mmol/kg zeolita u slučaju termičkog tretiranja zeolita (100°C) i zagrevanja rastvora SDBAH (80°C ). Način vezivanja između površinskog modifikatora i zeolita ispitan je metodama DTA, TG, DTG i IR analiza. Tokom postepenog zagrevanja u atmosferi vazduha, adsorbovana organska faza se oksiduje što se manifestuje egzotermnim pikovima na DTA krivama. Adsorpcija vodene pare opada sa porastom sadržaja organske faze do vrednosti 75 mmol/kg, što se može pripisati povećanju hidrofobnosti uzoraka organo-zeolita. Sa daljim povećanjem sadržaja organske faze, adsorpcija vodene pare je intenzivnija. U radu je ispitana desorpcija SDBAH sa organo-zeolita pri različitim pH vrednostima i jonskim jačinama vodenih rastvora. Rezultati su pokazali da su organo-zeoliti sa sadržajem SDBAH do vrednosti 75 mmol/kg zeolita stabilni u svim primenjenim uslovima.

The adsorption of stearyldimethylbenzylammonium chloride (SDBAC) on the clinoptilolite-heulandite rich tuff in dependence on the applied temperature was studied. The maximal amount of sorbed SDBAC was 123 mmol/kg in the case of thermally treated zeolite tuff (100°C) and a warm surfactant solution (80°C). The amount and properties of water adsorbed on the organo-zeolite (OZ) as well as the bonding between the organic species and the zeolite were investigated by DTA, TG, DTG and IR analyses. During gradual heating in an oxidizing atmosphere, the adsorbed organic material was oxidized, giving rise to significant exothermic peaks. The adsorption of water vapor decreased with increasing SDBAC loading up to 75 mmol/kg of zeolite, which can be ascribed to an intensification of the hydrophobic characteristics of the surface. With loadings above the 75 mmol/kg, the adsorption of water vapor increased. Desorption of SDBAC from the organo-zeolite under environmentally relevant conditions: distilled water, pH 3 and 10 buffers, as well as aqueous NaCl and CaCl2 solutions, was investigated. OZs with loadings up to their external cation exchange capacity value (75 mmol/kg) were stable under all of the applied conditions.