Synthesis and characterization of biodegradable polymer-based organoclays and its application as adsorbent material for wastewater treatment

Abstract

In this work, a white Ca-bentonite from Boane region in Southern Mozambique was successively subjected to Na2CO3 activation and organo-modification process aiming to use the resulting hybrids as adsorbent materials in wastewater treatment. In the organo-modification process, the study explored a different route of organoclays production. Instead of the conventional organo modification route based on surfactants, the study used the so-called “surfactant-free organo modification approach”. Experimental results confirmed the successful ion exchange of Ca2+ ions with Na+ ions since the cation exchange capacity (CEC) and Na/Ca ratio increased, respectively, from 67.5 up to 74 meq/100 g clay and from 2.94 up to 15.8, as the concentration of Na2CO3, activation temperature and stirring time varied, respectively, from 2 to 6 wt.%, 25 to 65 ◦C and from 2 to 4 h. X-ray diffraction (XRD) confirmed that the organo-modification process using the “surfactant free approach” has taken place since the main smectite peak of the polymer modified clays shifted to the left side up to 18.4A o . Scanning Electronic Microscopy (SEM) images of the polymer modified clays presented compact layers in their structures, suggesting that the protonated amine functional groups at the ends of the polymer chains have attached the surface of the clay. The sodium activation and organo-modification processes increased the phenol adsorption capacity of the clay. Phenol adsorption capacity increased in the order of increasing polymer concentration. Under the current study conditions, the maximum adsorbed phenol was observed at the maximum polymer concentration, 7.5 wt.% polymer.