clay and arsenic-acid

This work aims at exploring a novel environment-friendly nanomaterial based on natural clay minerals for arsenic removal in aqueous samples. Halloysite nanotubes (HNTs) were selected as the substrate with Mn oxides loaded on the surface to enhance its arsenic adsorption ability and then grafted onto the SiO

Topics: Adsorption; Arsenates; Arsenic; Arsenites; Clay; Hydrogen-Ion Concentration; Kinetics; Nanotubes; Oxides; Silicon Dioxide; Water; Water Pollutants, Chemical; Water Purification

Topics: Adsorption; Arsenates; Clay; Hydrogen-Ion Concentration; Iran; Iron; Kinetics; Manganese; Models, Theoretical; Surface Properties; Thermodynamics; Wastewater; Water Pollutants, Chemical; Water Purification

Batch desorption experiments and bench-scale electrokinetic experiments were performed to elucidate the electrokinetic remediation mechanisms of arsenate from artificially contaminated kaolinite. The electrokinetic experiments in which a constant voltage was applied demonstrated that high soil pH favored arsenate remediation with respect to both the remediation time and electricity consumption. It was also demonstrated that applying a pulse voltage (1 h ON, 1 h OFF) significantly improved the electricity consumption efficiency when the soil pH was maintained at the initial value during the experiments; this trend was not observed when the soil pH was gradually increased from the cathode side. These electrokinetic experimental results, with the support of arsenate desorption data obtained from batch experiments, indicate that the remediation rate-limiting step varied with soil pH. When the soil pH was maintained at the initial value of 7.2 during the experiments, arsenate desorption was the remediation rate-limiting step rather than the migration of dissolved arsenate toward the anode. Conversely, when the cathode pH was not controlled and the soil pH was correspondingly increased gradually from the cathode side, the migration of hydroxyl and desorbed arsenate ions toward the anode played a more important role in the control of the overall remediation efficiency.

Topics: Adsorption; Aluminum Silicates; Arsenates; Clay; Electrochemistry; Electrodes; Environmental Restoration and Remediation; Hydrogen-Ion Concentration; Soil Pollutants

An attempt has been made to elucidate the effects of soil properties on arsenate adsorption by modeling the relationships between adsorption capacity and the properties of 16 Chinese soils. The model produced was validated against three Australian and three American soils. The results showed that nearly 93.8% of the variability in arsenate adsorption on the low-energy surface could be described by citrate-dithionite extractable Fe (Fe(CD)), clay content, organic matter content (OM) and dissolved organic carbon (DOC); nearly 87.6% of the variability in arsenate adsorption on the high-energy surface could be described by Fe(CD), DOC and total arsenic in soils. Fe(CD) exhibited the most important positive influence on arsenate adsorption. Oxalate extractable Al (Al(OX)), citrate-dithionite extractable Al (Al(CD)), extractable P and soil pH appeared relatively unimportant for adsorption of arsenate by soils.

Topics: Adsorption; Aluminum; Aluminum Silicates; Arsenates; Australia; Carbon; Chemical Phenomena; Chemistry, Physical; Clay; Humic Substances; Hydrogen-Ion Concentration; Iron; Models, Theoretical; Soil; Soil Pollutants; United States