Synthesis of organoclays and clay-containing hydrogels and investigation of their metal adsorption behaviour

In this study, hydrogels containing halloysite nanotube (HNT) clay, montmorillonite (MMT) clay, carboxymethylcellulose (CMC) biopolymer, acrylamide (AM) and 2-acrylamido-2-methyl-1-propane sulfonic acid (AMPS) were synthesised using free radical polymerisation and in-stu polymerisation methods. HNT and MMT clays were synthesized by converting them into organoclays. Hydrogels, raw clay and organoclays (FTIR, XRD and TGA) were characterized, and UV-Vis spectrophotometer was used for adsorption measurements. The effects of AMPS amount, CMC biopolymer and clay species on Cu(II) adsorption of hydrogels were investigated. The effects of hydrogel type, clay type, clay amount, solution pH, initial metal concentration and contact time on Cr(VI) adsorption of hydrogels were investigated. It was determined that AM/AMPS(240) (1e) hydrogel was the most adsorbing hydrogel for Cu(II) ions, while AM/MMT(4%) (6c) hydrogel was the most adsorbing hydrogel for Cr(VI) ions. The Cr(VI) adsorption results of 6c hydrogel were found to be in accordance with Langmuir Tip2 and Freundlich adsorption isotherms and Pseudo-second order kinetic model. Cu(II) and Cr(VI) adsorption of HNT and MMT clays modified with ionic liquid and quaternary ammonium salt was investigated in terms of pH, initial metal concentration and adsorbent amount. Cu(II) and Cr(VI) metal adsorption of the synthesised organoclays were evaluated according to Langmuir Type1, Langmuir Type2, Freundlich, Temkin, Dubinin-Radushkevich (D-R), and Harkins-Jura adsorption isotherms. In addition, the effects of hydrogels containing AM, AMPS (0, 60, 300) and CMC/HNT clays on MDA-MB-231 breast cancer cell line were investigated in vitro by XTT assay method.