Environmentally Benign Adsorption Materials for Removing Arsenic from Aquatic Environment

Abstract

Adsorptive removal of arsenic using adsorption gels prepared from orange and apple juice residues was reviewed by summarizing the authors' previous papers. Orange and apple juice residues contain a large amount of pectin, partly methyl-esterified pectic acid, which exhibits high affinity for high-valent metal ions such as iron(III), rare earths(III) and zirconium(IV). Anionic species of arsenic(III, V) are effectively and selectively adsorbed on pectic acid gel via loading these high-valent metal ions. Raw orange juice residue was saponified using calcium hydroxide to improve the loading capacity for these metal ions. It was found that zirconium(IV) exhibits the most suitable adsorption behaviors for arsenic(III, V). Similar result was obtained also for apple juice residue. An actual sample of acid mine drainage from the Horobetsu mine which contained a high concentration of iron and low concentration of arsenic, was tested using the adsorption gel prepared from orange juice residue and the results were compared with those from the current treatment process based on coprecipitation with iron hydroxide. The new process using the abovementioned adsorption gel was proposed for treatment of such acid mine drainage.

Adsorption isotherm and thermodynamic studies of As(III) removal from aqueous solutions using used cigarette filter ash

“…The used cigarette filter ash exhibits maximum As(III) removal near neutral pH because of the speciation of As(III). At pHs below 8, As(III) is mainly present in solution as H 3 AsO 3 and at pHs greater than 8 as species H 2 AsO − 3 , HAsO 2− 3 and AsO 3− 3 (Inoue et al 2018). Based on the findings of this study, pH zpc for used cigarette filter ash is about 8.57.…”

“…As the results show, on the basis of the values of R 2 , it can be decided that experimental data are more consistent with the Langmuir isotherm model. Many researchers have confirmed the validness of the Langmuir model for the adsorption process (Sigdel et al 2016;Chowdhury et al 2018;Inoue et al 2018). In accord with the Langmuir model, the maximum adsorption capacity (q m ) and Langmuir constant (K L ) for the adsorption process were calculated as 33.33 mg/g and 0.90 L/g, respectively.…”