RESUMO
Abstract This study describes the use of bentonite in suspension for the caffeine adsorption (pollutant of emerging concern) by taking different conditions of the pH, adsorbent mass, adsorbent calcination temperature and interferents into account. The results were compared with those obtained using bentonite immobilized in alginate beads. The acid medium has a greater efficiency for the caffeine adsorption and the adsorbent calcination temperature exerts, due to structural changes. Caffeine removal higher than 90% was obtained at optimized conditions. The Langmuir model indicated a better fit of the data and the adsorption capacity of caffeine onto bentonite. The bentonite immobilized led to a slower adsorption process in relation to the suspended.
Assuntos
Poluentes Químicos da Água/isolamento & purificação , Bentonita/química , Cafeína/química , Termodinâmica , Cafeína/efeitos adversos , Adsorção , Poluentes Ambientais/isolamento & purificação , Temperatura Alta , Concentração de Íons de Hidrogênio , Modelos TeóricosRESUMO
The study was carried out to understand the interaction of Zinc (II), which happens to be an essential micronutrient and essential element for all life, with a mineral surface, Montmorillonite Clay which happens to be an important soil constituent and is compared with carbonaceous solid phase such as Activated Carbon. It was found that retention takes place through chemisorptions, ion exchange and probably precipitation also involved at higher pH. The effect of various parameters such as pH, contact time, adsorbent dosage and initial concentration of the metal ion on the kinetics of adsorption was studied. At higher pH of the clay system, zinc becomes less soluble. The adsorption behaviour of zinc using a blend of Montmorillonite Clay, Activated Carbon was also studied. It was found that when the percentage of Activated Carbon in the blend increases, the percentage retention decreases. The release of Zn (II) was studied using different extracting solutions. The desorption was insignificant indicating the possibility of formation of inner sphere complexes. The adsorption data was also applied to the effluent from Zinc Smelting Industry.
Assuntos
Adsorção , Silicatos de Alumínio , Bentonita/química , Carbono/química , Cromatografia por Troca Iônica , Monitoramento Ambiental/instrumentação , Concentração de Íons de Hidrogênio , Hidrólise , Cinética , Metais/química , Fatores de Tempo , Zinco/químicaRESUMO
The miocene clay deposits at G. Hamza- G. Um Qamar off the Cairo Ismailia Road are texturally classified as silt bearing, clay-rich mudstones. X-Ray powder diffraction analysis indicates that the main clay minerals present are montmorillonite and kaolinite. Urn Qamar mudstones contain higher percentages of montmorillonite and lower proportions of Kaoloinite than those of G. Hamza. The IR absorption bands of these clay minerals in the OH and Si-O stretching regions, as well as those in the OH and Si-O bending regions have been studied in detail. The FTIR analysis indicates that Mg[II] and Fe [II] are present in minor amounts in the montmorillonite structure