Evaluation of low-cost geo-adsorbents for As(V) removal

Natalia Inchaurrondo*, Carla di Luca, Patricia Haure, Gregor Žerjav, Albin Pintar, Cristina Palet

*Corresponding author for this work

Research output: Contribution to journalArticleResearchpeer-review

Abstract

Four low-cost iron-bearing geo-adsorbents were tested for As(V) removal without pretreatment: Montanit300® (M), diatomite (D), pumice (P) and black sand (BS). The solids were carefully characterized by different analytical techniques (SEM-EDX, TPD-pyridine, N2 Physisorption, XRD and point of zero charge). The adsorption of As(V) was evaluated through isotherms and kinetic studies (bottled water matrix, pH0=8,25 g/L of solids), and experiments addressing pH effect (pH0=3.6,7.5,11) and the presence of interfering anions (Cl, SO42−, NO3, PO43−). Experimental results were fitted to the Freundlich and Langmuir sorption isotherms. Under the employed conditions, P showed negligible adsorption, M and D presented adsorption capacities around 0.02 mg/g and, in spite its lower surface area, BS displayed the highest value (0.045 mg/g), which relates to a higher density of Fe species, M and D samples were easily regenerated (80%–100% desorption) through a basic treatment (0.01 M NaOH) and presented fast adsorption kinetics (1 h for D and seconds for M). BS showed a slow adsorption kinetic (24 h) and poor regeneration (only 50% desorption). Sample M (natural zeolite) resulted a promising option due to its remarkably fast adsorption kinetic, easy regeneration and adsorption capacity suitable for systems with relatively low As concentrations.

Original languageEnglish
Article number101341
JournalEnvironmental Technology and Innovation
Volume21
DOIs
Publication statusPublished - Feb 2021

Keywords

  • Adsorption mechanism
  • As(V) removal
  • Fe-bearing minerals
  • Geo-adsorbents

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