Comparative studies on Cr(VI) ions by reduced graphene oxide and SBA-16 mesoporous silica and their composites with Cu-MOF

This work examines the adsorption performance of novel adsorbents such as reduced graphene oxide (GO) and mesoporous silica (SBA-16) which synthesized from rice husk ash, and then composited with Cu-metal organic framework (Cu-MOF) for the first time. XRD, FTIR, EDX, FE-SEM and N2 adsorption techniques were studied. The adsorption performance of investigated adsorbents toward removal of hexavalent chromium (Cr(VI)) ions was carried out as a function of pH and initial concentration of Cr(VI) ions. The obtained GO and SBA-16 samples exhibited a superior porosity than that of Cu-MOF, Cu-MOF/GO and Cu-MOF/SBA-16 that owed to close of internal pores in both GO and SBA-16 samples upon loading Cu-MOF particles. The Langmuir and Temkin models prescribed Cr(VI) adsorption more accurately. The maximum adsorption capacity of Cr(VI) was 86.1 mg/g by GO while 77 and 66.7 mg/g by Cu-MOF/GO and Cu-MOF/SBA-16, respectively. The adsorption Cr(VI) mechanism followed the pseudo-first order kinetic model. Therefore, the as-prepared GO and SBA-16 derived from rice husk ash and their composites with Cu-MOF can candidate as effective adsorbents for removal of Cr(IV) ions from their aqueous media.