Highly efficient TiO2-pillared smectite clay with Ni and Co doping for Rhodamine B removal: kinetics of adsorption and photodegradation

Clay exhibits the capability to adsorb dyes such as Rhodamine B (RhB); practical application reveals its susceptibility to desorption, however, compromising its efficacy for RhB removal. To address this concern, modification of Natural Boyolali Region Clay (NBR Clay) was conducted by introducing TiO2 pillars and incorporating Co and Ni as dopants. This modification aimed to augment the clay's photodegradation capability and its RhB removal capacity. The principal objective of this study was to assess the characteristics of TiO2-pillared clay doped with Co and Ni and to evaluate its effectiveness in RhB removal. The prepared samples were analyzed using Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis with differential scanning calorimetry (TGA-DSC), and gas sorption analysis (GSA). TGA results indicated stability for all samples up to 650 degrees C, except for Co-Ti/NBR Clay. After 2.5 min, the adsorption capacity of both NBR Clay and NBR Clay+ethanol (EtOH) significantly surpassed that of Ti/NBR Clay, Ni-Ti/NBR Clay, and Co-Ti/NBR Clay. However, the adsorption energy of Ti/NBR Clay, Ni-Ti/NBR Clay, and Co-Ti/NBR Clay exceeded that of NBR Clay and NBR Clay+EtOH. Furthermore, all samples adhered to the Langmuir isotherm model, indicative of a physisorption mechanism. Notably, after 80 min, the percentage of photocatalytic degradation for plain clay reached 99.61%, and this value increased with the introduction of TiO(2 )and doping. The Co-Ti/NBR Clay sample exhibited the highest degradation rate at 99.97%. These findings underscore the favorable influence of TiO2 addition and doping on enhancing RhB removal efficiency.