Application of zeolite-activated carbon macrocomposite for the adsorption of Acid Orange 7: isotherm, kinetic and thermodynamic studies

Abstract

In this study, the adsorption behavior of azo dye Acid Orange 7 (AO7) from aqueous solution onto macrocomposite (MC) was investigated under various experimental conditions. The adsorbent, MC, which consists of a mixture of zeolite and activated carbon, was found to be effective in removing AO7. The MC were characterized by scanning electron microscopy (SEM), energy dispersive X-ray, point of zero charge, and Brunauer-Emmett-Teller surface area analysis. A series of experiments were performed via batch adsorption technique to examine the effect of the process variables, namely, contact time, initial dye concentration, and solution pH. The dye equilibrium adsorption was investigated, and the equilibrium data were fitted to Langmuir, Freundlich, and Tempkin isotherm models. The Langmuir isotherm model fits the equilibrium data better than the Freundlich isotherm model. For the kinetic study, pseudo-first-order, pseudo-second-order, and intraparticle diffusion model were used to fit the experimental data. The adsorption kinetic was found to be well described by the pseudo-second-order model. Thermodynamic analysis indicated that the adsorption process is a spontaneous and endothermic process. The SEM, Fourier transform infrared spectroscopy, ultraviolet-visible spectral and high performance liquid chromatography analysis were carried out before and after the adsorption process. For the phytotoxicity test, treated AO7 was found to be less toxic. Thus, the study indicated that MC has good potential use as an adsorbent for the removal of azo dye from aqueous solution.

Direct Blue 71 Removal from Aqueous Solutions by Adsorption on Pistachio Hull Waste: Equilibrium, Kinetic and Thermodynamic Studies

“…The pH of zero-point charge (pHpzc), of pH was analyzed according to the method proposed by Lim et al (27), where 50 ml of 0.01 M NaCl solution was placed in a closed Erlenmeyer flask. The pH was studied over a pH range of 2-12 using the pH meter (WTW, Germany).…”

“…Each PHW sample was then added to the solution, and the final pH was measured after 24 hours agitation at room temperature. The pHpzc is the point where the curve pH final versus pH initial crosses the line pH initial = pH final (27 (25). To illustrate the functional groups, present on the surface of the adsorbent, Fourier transform infrared (FTIR) spectra were collected between 450 and 4000/cm using a Nicolet spectrometer.…”

“…The first and important one is that contact time between the pollutant and the adsorbent. Because these important parameters are effected on the practical application of adsorption process (27). Testing the effect of contact time on the removal rate was performed to achieve the adsorption process equilibrium time at intervals 0-210 minutes.…”

“…Therefore, the initial concentration of adsorbate solution is very important in the adsorption process (27). As figure 7 show, by increasing dye concentration, the removal efficiency of PHW is reduced.…”

Modeling of Competitive Ultrasonic Assisted Removal of The Crystal Violet and Aura Mineo using Mwcnts Functionalized by N-(3-Nitrobenzylidene)-Nˊ-Trimethoxysilylpropyl-Ethane-1,2-Diamine:Equilibrium, Kinetics and Thermodynamic Study

“…Adsorption equilibrium isotherm is designed based on mathematical relation of the amount of adsorbed target per gram of adsorbent (q e (mgg -1 )) to the equilibrium non-adsorbed amount of dye in solution (C e (mgL -1 ) at fixed temperature 48,49 . Isotherm studies are divided to well-known models such as Langmuir, Freundlich, Temkin and DubininRadushkevich based on well-known conditions.…”