Cr (VI) and Cu (II) removal from aqueous solutions with geopolymers

In this study, Cr6+ and Cu2+ heavy metal removals from aqueous solutions were investigated by using the adsorption method with 4 different geopolymers (JMK, JUK, JFUK15, and JFUK24) obtained by activating industrial wastes with NaOH. Class F - fly ash and metakaolin were used in the synthesis of geopolymers. XRF analyses were used to determine the chemical composition of the geopolymer materials produced in the study, XRD analyses to determine the phases in the internal structure of the materials, SEM analyses to determine their microstructures, and FTIR analyses to examine the functional bond properties. In the removal of heavy metals (Cr6+, Cu2+) from aqueous solutions by adsorption method, synthetic solutions prepared in the laboratory were used and the removal studies were carried out with a batch system. The effect of different parameters such as initial pH (3-11), adsorbent dose (0,05-1,0 g/50 mL), initial heavy metal concentration (25-200 mg/L), temperature (298-328 K), and contact time (30-1440 minutes) were investigated. The compatibility of Cr6+ and Cu2+ adsorption with Langmuir, Freundlich, Temkin and Dubinin-Redushkevich isotherms were determined and adsorption kinetics and adsorption thermodynamics were investigated for both heavy metals. The results obtained from the studies showed that the geopolymers obtained as a result of the activation of selected industrial wastes with NaOH can be an effective, environmentally friendly, affordable, easily available, economical and alternative adsorbent in removing Cr6+ and Cu2+ ions from aqueous solutions compared to other adsorbents.