Highly efficient ultrasonic-assisted removal of Hg(II) ions on graphene oxide modified with 2-pyridinecarboxaldehyde thiosemicarbazone: Adsorption isotherms and kinetics studies

Abstract

A novel adsorbent, based on modifying graphene oxide (GO) chemically with 2-pyridinecarboxaldehyde thiosemicarbazone (2-PTSC) as ligand, was designed by facile process for removal of Hg(II) from aqueous solution. Characterization of the adsorbent was performed using various techniques, such as FT-IR, XRD, XPS, SEM and AFM analysis. The adsorption capacity was affected by variables such as adsorbent dosage, pH solution, Hg(2+) initial concentration and sonicating time. These variables were optimized by rotatable central composite design (CCD) under response surface methodology (RSM). The predictive model for Hg(II) adsorption was constructed and applied to find the best conditions at which the responses were maximized. In this conditions, the adsorption capacity of this adsorbent for Hg(2+) ions was calculated to be 309mgg(-1) that was higher than that of GO. Appling the ultrasound power combined with adsorption method was very efficient in shortening the removal time of Hg(2+) ions by enhancing the dispersion of adsorbent and metal ions in solution and effective interactions among them. The adsorption process was well described by second-order kinetic and Langmuir isotherm model in which the maximum adsorption capacity (Qm) was found to be 555mgg(-1) for adsorption of Hg(2+) ions over the obtained adsorbent. The performance of adsorbent was examined on the real wastewaters and confirmed the applicability of adsorbent for practical applications.

Poly(benzoxazine‐co‐sulfur): An efficient sorbent for mercury removal from aqueous solution

“…Oxygen, hydroxyl groups, nitrogen, and sulfur atoms of poly(BA‐ala‐ co ‐sulfur) may bind to Hg 2+ ions by electron pair‐sharing to form corresponding metal complexes (Figure ). Nitrogen and sulfur atoms donate a lone pair electrons more readily than oxygen atoms due to lower electronegativity . At lower pH, these binding sites in poly(BA‐ala‐ co ‐sulfur) are protonated resulting in a weak affinity with Hg 2+ .…”

“…At lower pH, these binding sites in poly(BA‐ala‐ co ‐sulfur) are protonated resulting in a weak affinity with Hg 2+ . At higher pH, they became more naked and the ions can easily be adsorbed . In addition, the oxygen containing groups such as hydroxyl is ionized at pH higher than 4 and could be more active in electrostatic ionic attractions …”

Preconcentration and determination of ceftazidime in real samples using dispersive liquid-liquid microextraction and high-performance liquid chromatography with the aid of experimental design

“…Different variables can affect the extraction yield in the DLLME procedure such as the volume of extraction solvent and disperser solvent, salt effect, sample volume, centrifuge rate, centrifuge time, and extraction time. Design of experiment have been widely utilized in literatures to test the factors for main effects to reduce their numbers [25][26][27][28][29]. In the present work, a two-level Taguchi design with an L 8 (2 7 ) matrix was applied for screening of the significant factors.…”

Statistical optimization and modeling approach for azo dye decolorization: Combined effects of ultrasound waves and nanomaterial‐based adsorbent

“…However, adsorption is an effective, single, easy and cost‐effective option for treatment of wastewater effluent and is extensively applied for removal of contaminants from aqueous environments, while recently ultrasound irradiation was applied by our groups to accelerate the chemical process due to the phenomenon of acoustic cavitation . The formation, growth and collapse of bubbles as well as microscopic turbulence within interfacial films surrounding adsorbent and adsorbate by the propagation of a pressure ultrasound wave increases the mass transfer rate .…”