ABSTRACT
Polymer-supported hydrated iron(III) oxide (PHIO) was successfully applied as adsorbent for arsenic removal in a wastewater treatment plant in Nandan, China. The practical PHIO adsorbent samples (PHIO-P) were collected from the adsorption column of the wastewater treatment plant, and desorption experiments of the adsorbent were carried out. Our results showed that the formation of precipitates on the surface of PHIO-P might block the porous channel of the adsorbent and decrease its arsenic adsorption capacity. In the dynamic arsenic desorption experiment, the arsenic desorption equilibrium was achieved more quickly at decreasing desorption velocity, and higher arsenic desorption efficiency was obtained at increasing NaOH concentration in regenerant. It was found that the PHIO-P adsorbent could be well regenerated at 1.0 M NaOH solution and desorption velocity of 5 BV h-1. Comparing with the raw adsorbent, the maximum arsenic adsorption capacity of PHIO-P decreased by 41.1% after practical running for 26 months. Additionally, the frequently used waste PHIO adsorbent could be treated as non-hazardous material in the arsenic-containing wastewater treatment process after long-time use.
Subject(s)
Arsenic/chemistry , Ferric Compounds/chemistry , Polymers/chemistry , Wastewater/chemistry , Water Pollutants, Chemical/chemistry , Water Purification/methods , Adsorption , China , Hydrogen-Ion Concentration , Water Purification/instrumentationABSTRACT
In this paper, goethite waste from hydrometallurgy of zinc was used as a raw material for arsenic adsorbent preparation. The goethite waste adsorbent (GWA) was characterized with scanning electron microscope (SEM), X-ray powder diffraction (XRD), and particle size distribution analysis. The adsorption of As(III) on GWA was studied as a function of contact time, pH, and coexisting anions. The safety of GWA usage in the wastewater treatment process was assessed by toxicity characteristic leaching procedure (TCLP) tests. The equilibrium adsorption data fitted well with the Langmuir isotherm model, and the maximum adsorption capacity of As(III) on GWA was 51.47 mg.g-1. GWA showed higher adsorption capacity at weak alkaline pH values (7.0-9.5). The coexisting PO43- and SiO32- presented significant adsorption competition with As(III) in aquatic systems. No significant heavy metals leaching was observed for GWA and As(III) loaded GWA in TCLP tests, which implied the safety of GWA as an adsorbent for arsenic containing wastewater treatment.
