Effect of chloride and nitrate salts on Hg(II) sorption by raw and pyrolyzed malt spent rootlets

Abstract

BACKGROUND Mercury is considered to be one of the most harmful metals for human health and the environment. Biomass based materials and the corresponding biochars show promising potential as Hg(II) sorbents. Sorption is an effective process to remove Hg(II) from polluted waters, and is mainly affected by water chemistry. The sorption efficiency of malt spent rootlets and their biochar was evaluated at various ionic strength levels with two different salts, NaCl and NaNO3. RESULTS For both materials, the salts were added at concentrations of 1, 0.5, 0.1, 0.01, and 0.001 mol L−1. At pH 5, Hg(II) removal was not significantly affected by the presence of NaNO3. High Hg(II) removal was obtained even at high NaNO3 concentrations; 53% at 1 mol L−1 NaNO3. A significant decrease of Hg(II) sorption was observed with the increase of NaCl concentration. Hg(II) removal was 55% and 20% at 1 mmol L−1 and 1 mol L−1 NaCl, respectively. CONCLUSIONS The differences observed in salinity effect can be related to the different counter ions present in the salts. Low Cl− or NO3− concentrations did not interfere strongly with mercury sorption, but excess Cl− formed mercury species with negative charge, which demonstrated lower sorption. © 2017 Society of Chemical Industry

Influence of sulfide, chloride and dissolved organic matter on mercury adsorption by activated carbon in aqueous system

“…AC in "Hg + DOM" condition had the lowest q e (10.4 μg g − 1 ). In past studies, chloride interacting with Hg to form a stable complex was considered as the reason for decreasing the q e of adsorbent [41,42]. The additional sulfide seems to affect Hg adsorption on AC slightly.…”

“…Chen et al [43] reported that Hg 0 reemission rates from the wet flue gas desulfurization slurry increased about 4 μg m − 3 as the pH values increased from 3 to 7; the Hg 0 reemission rate decreased with increases chloride concentration. The acid condition could remain Hg + in the dissolved phase, as a result, Hg adsorption test was generally carried out under pH 3-5 [41,44,45]. However, the range of pH value is 6-8 in natural aquatic system.…”

Peer Review #1 of "Recent advances in biochar application for water and wastewater treatment: a review (v0.2)"

“…Their later study showed that the Hg sorption capacity by MSR biochars increased by a maximum factor of 6 for high-temperature (750-900℃) biochars compared to the raw material (Manariotis et al, 2015). Hg(II) sorption onto both materials carried on mainly through neutral species (Boutsika et al, 2017). Shi et al (2020) developed a ZnCl 2 -modified glue residue biochar for Cr(VI) sorption.…”

Biochars and Their Use as Transesterification Catalysts for Biodiesel Production: A Short Review

“…Generally, biochar presents high surface area and a significant amount of surface groups (acidic or basic) that can participate in adsorption processes. The biochars can be used as fuels, immobilize heavy metals, pesticides and other organic pollutants, prevent bacteria and nitrates leaching in water, activate persulfates for the oxidation of pollutants, and act as catalysts or catalyst supports [17][18][19][20][21]. In the latter case, the composition of ash should be carefully examined because it may have catalytically active or poisoning species.…”