Remoção de contaminantes orgânicos da água utilizando um aerogel à base de alginato graftizado com sílica funcionalizada

Abstract

The high production and consumption of petrochemical derivatives have increased issues related to the pollution of many ecosystems. To abate this concerning scenery, several methodologies have been studied and tested. Among them, adsorption has received great attention mainly due to its advantages compared to other processes. Herein, this study reports the development of a hydrogel capable of adsorbing some petrochemical pollutants. The hydrogel (denoted as GEL-SBA15) was formulated using a polysaccharide (sodium alginate, Alg) grafted with mesoporous silica (ASBA-15) and polyvinyl alcohol) (PVA). A freeze-thaw method was used to crosslinking it physically. GEL SBA15 was characterized using diverse analytical techniques, which revealed that the use of the grafted Alg endowed the hydrogel with enhanced physical and thermal stability compared to a sample prepared with raw Alg. Batch adsorption experiments showed that GEL-SBA15 has a high adsorption capacity towards the two selected pollutants; benzene (1482.8 mg/g) and toluene (596.6 mg/g). The results were obtained using a low dosage of GEL-SBA15 (10 mg) and mild experimental conditions (pH 7.0, at 25 ºC). Kinetic analysis indicated that the benzene and toluene adsorption onto GEL-SBA15 follows pseudo-second order kinetics. Also, the experimental data were well-fitted by the Freundlich isotherm model. Finally, adsorption/desorption experiments showed that GEL-SBA15 can be recycled and reused for at least 6 cycles without noticeable loss of adsorption performance. The results reported in this study suggest that the grafting of SBA 15 on the Alg backbone is an effective strategy to enhance the stability of the hydrogel as well as its adsorption capacity towards the two selected pollutants. Due to this, this hydrogel can be ranked as a promising adsorbent material to remove petrochemical derivates from water.