Optimization of magnetic powdered activated carbon for aqueous Hg(II) removal and magnetic recovery

Abstract

Activated carbon is known to adsorb aqueous Hg(II). MPAC (magnetic powdered activated carbon) has the potential to remove aqueous Hg to less than 0.2 μg/L while being magnetically recoverable. Magnetic recapture allows simple sorbent separation from the waste stream while an isolated waste potentially allows for mercury recycling. MPAC Hg-removal performance is verified by mercury mass balance, calculated by quantifying adsorbed, volatilized, and residual aqueous mercury. The batch reactor contained a sealed mercury-carbon contact chamber with mixing and constant N(2) (g) headspace flow to an oxidizing trap. Mercury adsorption was performed using spiked ultrapure water (100 μg/L Hg). Mercury concentrations were obtained using EPA method 245.1 and cold vapor atomic absorption spectroscopy. MPAC synthesis was optimized for Hg removal and sorbent recovery according to the variables: C:Fe, thermal oxidation temperature and time. The 3:1 C:Fe preserved most of the original sorbent surface area. As indicated by XRD patterns, thermal oxidation reduced the amorphous characteristic of the iron oxides but did not improve sorbent recovery and damaged porosity at higher oxidation temperatures. Therefore, the optimal synthesis variables, 3:1 C:Fe mass ratio without thermal oxidation, which can achieve 92.5% (± 8.3%) sorbent recovery and 96.3% (± 9%) Hg removal. The mass balance has been closed to within approximately ± 15%.

Magnetic adsorbents for the treatment of water/wastewater—A review

“…Mercury (Hg), a toxic pollutant under section 307 (a) of the Clean Water Act (CWA), remains a challenge in water treatment due to its ability to bio accumulate due to very low regulatory concentrations [148]. Main sources of contamination of Hg are batteries, paper & pulp industries, oil refineries etc [149].…”

Effects of Fe2+ and Fe3+ ratio impregnated onto local commercial activated carbon coconut shell powder on the dye removal efficiency

“…In the recent years, several investigators (Oliveira et al, 2002;Zhang et al, 2007;Faulconer et al, 2012) have given attention to magnetic adsorbent applications, particularly because the used magnetic adsorbent is subsequently easily separated from the treated wastewater or slurries with a magnetic field in within a relatively short time (Indira and Lakshmi, 2010). The present study concerned on the modification of local commercial AC coconut shell powder to produce magnetic AC (MAC) for dye removal.…”

Preparation of magnetic ordered microporous carbon for the preconcentration of some phthalate esters followed by their determination by HPLC

“…The development of magnetic adsorbents with highly efficient extraction capacity has become a hot research field. Up to now, various MSPE adsorbents, such as polymers [29,30], C18 nanoparticles [28], ionic liquid [31], activated carbon [32], carbon nanotubes [33] and graphene [27] have been explored.…”