Removal Study of Crystal Violet and Methylene Blue From Aqueous Solution by Activated Carbon Embedded Zero-Valent Iron: Effect of Reduction Methods

Abstract

Zero valent iron (ZVI) particles were embedded into porous materials to avoid aggregation and separation problems in the controlled synthesis process. To investigate the adsorption mechanism of crystal violet and methylene blue, activated carbon (AC) and AC-based ZVI extraction by solid-phase and liquid-phase reduced approaches was conducted. Characterization methods of specific surface area, scanning electron microscopy (SEM), and x-ray diffractograms (XRD) were used to elucidate the structure of adsorbents, and the adsorption capacities of crystal violet and methylene blue were obtained under experimental conditions of various pH values (2.0–10.0), adsorption times (0–72 h), and temperatures (30–50°C). The adsorption of crystal violet/methylene blue was controlled by both chemisorption and reduction. The adsorption processes were fitted to a pseudo-second-order kinetic model, and that of reduction kinetics was suitable to pseudo-first-order kinetic model. The thermodynamic study revealed that the adsorption of crystal violet and methylene blue was endothermic and spontaneous, and the adsorption isotherms fitted well to the Langmuir model. Different adsorption capacities of crystal violet and methylene blue on various adsorbents were found, indicating that both the properties of adsorbents (pore size, specific surface area, and chemical functional groups) and the structures of adsorbates had significant effect on the removal of dye molecules.

Iron–Iron Oxide Core–Shell Nanochains as High-Performance Adsorbents of Crystal Violet and Congo Red Dyes from Aqueous Solutions

“…The pH PZC was found to be 9.2. This means that the adsorption of an anionic dye is favored at pH < pH PZC and, at the same time, due to the negatively charged surface of the adsorbent, it can be used for the adsorption of cationic dyes. , The results obtained for the CR adsorption are in good agreement with the pH PZC experiment, whereas the highest amount adsorbed for CV was recorded at neutral pH.…”

Simple adsorptive removal of crystal violet, a triarylmethane dye, from synthetic wastewater using Fe (III)-treated pine needle biochar

“…The values of the coe cient of determination (R 2 ) and standard error of estimation (SE est ) obtained with the tting of adsorption data to different kinetic models are presented in Table1.It is clearly evident from the values that the adsorption kinetics of CV on to untreated-and Fe(III) treated-PNB could be best accounted by the pseudo-rst order kinetics as this model resulted in the coe cient of determination Jubair et al, 2020,Foroutan et al, 2021, Wang et al, 2021 have reported the suitability of pseudosecond order kinetics for adsorption of CV onto different bio-adsorbents. However, we noted the superiority of pseudo-rst order model over the pseudo-second order model to account the adsorption kinetics of CV adsorption onto different PNB preparations.Table1.…”

“…Many plant-based wastes materials (Loulidi et al, 2020;Elsherif et al 2021., Homagai et al, 2022Imran et al, 2022) and chemically treated leaf powder (Al-shehri et al, 2021) have been tried for the removal CV dye from waters. To make the adsorption process more viable and cost-effective, a range of bio-based activated carbons (biochars) are synthesized from agricultural wastes (Mishra et al, 2021).Biochar is a carbon-rich solid product formed during pyrolysis from thermo chemically decomposed biomass at a predetermined temperature of around 400-500°C in the absence or limited supply of oxygen (Mohan et al, 2014).It contains functional groups like carboxyl, hydroxyl, and phenolic on its surface and possesses a high speci c surface area (Jung et al, 2013) and surface reactivity to result in enhanced adsorption capacity.Plant based biochars (Wathukarage et al, 2019;Khan et al, 2021), magnetic biochar Foroutan et al, 2021) and modi cations of activated carbon (Wang et al, 2021) have been evaluated for the scavenging CV from wastewaters. In the present investigation, we used pine needles biochar(PNB) produced by pyrolysis at 450°Cwhich is chemically stable as well as insolubleand also Fe(III) treated PNB which is directly used as an adsorbent for CV dye.This study reports the performance of Fe (III) treated PNB which is simple to prepare and adopt at the user's end for the effective removal ofdye contaminants.…”