A Study on Astrazon Black AFDL Dye Adsorption onto Vietnamese Diatomite

Abstract

In the present paper, the adsorption of Astrazon Black AFDL dye onto Vietnamese diatomite has been demonstrated. The diatomite was characterized by XRD, SEM, TEM, EDS, and nitrogen adsorption/desorption isotherms. The results show that diatomite mainly constituted centric type frustules characterized by pores as discs or as cylindrical shapes. The adsorption kinetics and isotherms of dye onto Vietnam diatomite were investigated. The experimental data were fitted well to both Freundlich and Langmuir in the initial concentration range of 400–1400 mg L−1. The average value of maximum adsorption capacity,qm, calculated from Freundlich equation is statistically similar to the average value of maximum monolayer adsorption capacity calculated from Langmuir equation. The thermodynamic parameters evaluated from the temperature dependent on adsorption isotherms in the range of 303–343 K show that the adsorption process was spontaneous and endothermic. The Webber and pseudo-first/second-order kinetic models were used to analyze the mechanism of adsorption. The piecewise linear regression and Akaike’s Information Criterion were used to analyze experimental data. The results show that the dye adsorption onto diatomite was film diffusion controlled and the goodness of fit of experimental data for kinetics modes was dependent on the initial concentration.

Synthesis of Iron Doped Zeolite Imidazolate Framework-8 and Its Remazol Deep Black RGB Dye Adsorption Ability

“…This behavior could be attributed to either a reversible adsorption or a back diffusion controlling mechanism [62]. The pseudo-first-or second-order kinetic models of Lagergren [33] or Ho and McKay [63], respectively, have been widely used to investigate the formal kinetics of adsorption processes [12,27,40,64]. However, the present experimental data could not apply to these models due to reversible adsorption.…”

“…where SSE is the total sum of squares equal to ∑ 1 ( exp − mean ) 2 ( mean is the mean value of ). The comparison of models was based on Akaike's Information Criterion (AIC) [38][39][40]. The AIC c determines how well the data support each model.…”

“…The times of phase transition calculated by the square of breakpoints varied from 36 to 100 minutes. The adsorption could be divided into two distinct phases by the time of phase transition: (i) main adsorption of RDB molecules within 0-100 minutes of the contact times: this process was rather slow compared to other adsorbents [40,57] in which the fast and instantaneous adsorption was observed; since the pore sizes of Fe-ZIF-8 or ZIF-8 are around 1 nm [45], the adsorption of RDB with four benzene rings in which each has a critical dimension of around 0.662 nm [60] on ZIF-8 limited the diffusion of the RDB molecule to the inner pore structure; however, abundant active adsorption sites could be obtained at its external surface, which is helpful to the adsorption of dye molecules; (ii) a gradual attainment of the equilibrium where only about 5-10% of the adsorption was encountered. This is due to the utilization of the all active sites on the adsorbent surface.…”

Aminopropyl Functionalised MCM-41: Synthesis and Application for Adsorption of Pb(II) and Cd(II)

“…Infrared spectra (IR) were recorded on an FT-IR spectrometer using IR-Prestige-21 (Shimadzu) in the KBr matrix in the range 4000-400 cm −1 . e point of zero charge (pH PZC ) of the aminopropyl functionalised MCM-41 materials was determined by the solid addition method [24,32]. 25 mL of 0.1 M NaCl was added to a series of 50 mL Erlenmeyer flasks.…”

Pineapple Bark Performance in Dyes Adsorption: Optimization by the Central Composite Design

“…For this reason, natural materials, agricultural and industrial waste, and biosorbents represent potential alternatives. Additionally, a large number of unconventional and lowcost adsorbents have been proposed by many researchers for the removal of dyes [11,12] including agricultural waste such as sawdust [13], bark [14], and orange peel [15] and industrial waste, namely, metal hydroxide sludge [16], red mud [17], ashes flying [18], clays [19][20][21], diatomites [22,23], zeolites [24,25], siliceous materials [26,27], biosorbents [28][29][30][31], and others (cyclodextrin [32,33], starch [34], cotton [35], etc.). e purpose of this work was to study the adsorption of a three-dye mixture that contained Methylene Blue, Brilliant Green, and Congo Red on the pineapple bark according to the surface response method using the central composite design that consists of optimizing physicochemical parameters such as pH, temperature, and mass of the adsorbent.…”