Enhancing Functionalities in Nanocomposites for Effective Dye Removal from Wastewater: Isothermal, Kinetic and Thermodynamic Aspects

Abstract

The adsorption process combined with electrocoagulation is a highly effective technique for dye removal. Calcinized and non-calcinized composites based on bentonite and sodium zeolite were prepared for adsorptive removal of Foron EBL blue, Terasil brown 2RFL, Torque blue PG, and Orange P3R dyes. Factors affecting the adsorption process, such as contact time, initial dye concentration, and temperature, were also explored in this study. Equilibrium data of natural clay composites was explained by Freundlich, Langmuir, Dubinin Radushkevich isotherm, Harkin Jura, and Temkin isothermal models. Harkin Jura isotherm model best fitted on the adsorption mechanism compared to Langmuir and Temkin isotherm model. Morphology of clay-based adsorbents and functional group arrangement were investigated by scanning electron microscopy (SEM) and Fourier-transform infrared spectroscopy (FTIR). The calcinized nano-composite material exhibited better adsorption capacity than non-calcinized nano-composite and could be employed as a low-cost alternative for dye removal.

An Eco-Friendly Modification of a Walnut Shell Biosorbent for Increased Efficiency in Wastewater Treatment

“…(1) E S < 8 kJ/mol indicates that the adsorption process is based on physical forces (such as van der Waals); (2) E S in the range of 8-16 kJ/mol suggests an ion exchange mechanism; and (3) E S values higher than 16 kJ/mol implies chemisorption processes [36,40]. As shown in Table S2, the mean free energy (E S ) values for many of our investigated systems ranged between 9.91-16.48 kJ/mol, suggesting that the adsorption process of MB and CV could rely on ion exchange mechanisms (electrostatic interactions between the negatively charged carboxylic (−COO − ) groups from biosorbents and positively charged amino groups from dyes).…”

Capability of TiO2 and Fe3O4 nanoparticles loaded onto Algae (Scendesmus sp.) as a novel bio-magnetic photocatalyst to degration of Red195 dye in the sonophotocatalytic treatment process under ultrasonic/UVA irradiation

“…With 1/n and K F values of 0.4036 and 12.68 mg1 -n g -1 L -n , respectively, the adsorption process and reaction's intensity were favorable. In addition, the Harkins–Jura model confirmed the adsorption of R195 molecules onto the heterogeneous surface 33 . In contrast, the presence of exothermic and physical adsorption between R195 molecules and Scendesmus, Fe 3 O 4 , and TiO2 was indicated by the positive value of b T (43.266 J/mol) in the Temkin isotherm 32 .…”

“…At 300 mg/l of R195, the empirical data were best described by the pseudo-first-order (PFO) model with R 2 = 0.9925. These findings reveal a correlation between the quantity of physical R195 adsorption and the increased driving force responsible for the efficient diffusion of R195 molecules to the surface of Scendesmus /Fe 3 O 4 /TiO 2 and their occupation of the remaining active sites 33 . The pseudo-second-order (PSO) model best described the adsorption process of 100, 200, and 400 mg/l of initial R195 concentrations, with R 2 values of 0.9983, 0.9731, and 0.9722, respectively, when considering chemisorption as the predominant adsorption process with electron donor–acceptor and dispersal interactions 51 .…”

“…The fourth model examined to support the multilayer adsorption of iodine atoms onto the synthesized photocatalyst is the Harkins–Jura model, whose linear form (Eq. 9 ) is as follows 33 : where A H and B H are Harkins constants derived from the slope and intercept of the linear plots of q e 2 versus log C e , respectively 33 .…”

“…In the transition state theory (TST), the conventional Gibbs free energy, ΔG° (kJ mol -1 ), is defined by the following equations 6 : where ΔH° is the standard enthalpy (kJ mol -1 ) and ΔS° is the standard entropy (JK -1 mol -1 ) 5 . TST implies the temperature dependence of the apparent rate constant in the Henry equation 33 : where K B is the Boltzmann’s constant ( K B = 1.380510 –23 JK -1 ) and h is the Planck’s constant ( h = 1.380510 -23 Js) 33 . …”