Sorption and photocatalytic degradation of methylene blue on bentonite-ZnO-CuO nanocomposite

Abstract

This paper presents a method for removing organic dyes by sorption and photocatalytic processes on a bentonite bed modified with ZnO-CuO nanocomposite. The effect of the initial dye concentration and temperature on the amount of dye removed from the solution was investigated. The results obtained at equilibrium state allowed us to determine the equilibrium and kinetic models and the thermodynamic parameters for the studied processes. The Langmuir isotherm is the best model for describing the equilibrium processes for both sorption and sorption with photocatalysis. In terms of kinetics, both processes are accurately described by the pseudosecond order model, which demonstrates the chemical nature of sorption. Due to the negative ΔG values calculated from the tests, it was found that the studied processes are spontaneous. It was possible to obtain a better degree of purification of the dye solution using combined sorption and photocatalysis compared to the sorption process itself.

Sustainable removal of anodized aluminum dye by groundwater treatment waste: experimental and modeling

“…The Fourier transform infrared (FTIR) spectra of GWTW, SG dye and GWTW after the dye adsorption are presented in Figure 3 . The FTIR spectrum of GWTW showed the bands at 3300 and 1636 cm −1 which can be assigned to the H-bonded O–H stretching modes and H–OH bending vibration of the free adsorbed water, respectively ( Chao et al., 2018 ; Szostak and Banach, 2019 ; Yoon et al., 2005 ). Strong band at 957 cm −1 with shoulders at 1077 and 850 cm −1 comes from bending vibration of FeOH modes ( Ociński et al., 2016 ; Chao et al., 2018 ).…”

Preparation and Photocatalysis of CuO/Bentonite Based on Adsorption and Photocatalytic Activity

“…The pseudo-second-order dynamic model better fit the process under investigation; thus, a chemical mechanism controlled the adsorption rate of 1.4% CuO/bentonite (400 °C) composite for MB. Szostak and Banach from the Faculty of Chemical Engineering and Technology in Cracow, Poland, studied the kinetics of sorption and photocatalytic degradation of methylene blue photocatalysis onto a bentonite–ZnO–CuO nanocomposite and obtained similar results [ 23 ].…”

“…According to Szostak, the q max parameter had a higher value when looking at the sorption and photocatalytic degradation of methylene blue on a bentonite–ZnO–CuO nanocomposite, as well as a higher concentration (100 mg/L) for the combined photocatalytic–sorption process than for sorption itself. This shows that photodegradation occurred during the process [ 23 ]. Cui recycled CuO nanoparticles/zeolite six times to degrade MB, and the decolorization efficiency only decreased from 95% to 92.4%, which is comparable to this study, although this study needed a longer irradiation time [ 27 ].…”

“…However, it cannot be ignored that TiO 2 , ZnO, and CuO are easy to agglomerate and difficult to recover in water. Thus, many efforts have been made to immobilize the photocatalysts on some inert carriers, such as activated carbon [ 18 ], silica [ 19 ], zeolite [ 20 , 21 , 22 ], and bentonite [ 23 ]. Li [ 24 ] used activated carbon-loaded nano CuO to treat dye wastewater, and the removal rate of COD reached 84.6%.…”

“…Combining the adsorption and photocatalytic process can better remove dyes in solution and achieve a higher value of q max (maximum adsorption capacity). The difference in the amount of dye extracted from the solution during the two processes is due to photocatalytic degradation under UV irradiation [ 23 ]. However, there are few reports about the use of a CuO/bentonite composite for the degradation of MB in water.…”