Arsenate Adsorption on Goethite Nanorods in the Presence of Geochemical Constituents


Alidokht L., KARACA Ö., Shirzadeh N.

Proceedings of the 3rd International Conference on Environmental Geotechnology, Recycled Waste Materials and Sustainable Engineering (EGRWSE 2022), İzmir, Turkey, 15 - 17 September 2022, vol.370 LNCE, pp.397-407 identifier

  • Publication Type: Conference Paper / Full Text
  • Volume: 370 LNCE
  • Doi Number: 10.1007/978-981-99-4041-7_35
  • City: İzmir
  • Country: Turkey
  • Page Numbers: pp.397-407
  • Keywords: Adsorption, Arsenate, Geochemical constituents, Goethite nanorods, Kinetics
  • Çanakkale Onsekiz Mart University Affiliated: Yes

Abstract

The present study describes the adsorption kinetics of arsenate (AsV) from solution by synthetic goethite nanorods (GN) in the presence of clay mineral, calcite, and leonardite-derived humic acid (HA). Batch experiments were performed at different pH values (5.5, 7, 8.5) to obtain the adsorption kinetics of AsV using 1 g L−1 GN, 120 mg L−1 HA, 4 g L−1 calcite, and 20 g L−1 kaolinite. Experiments containing calcite were only performed at pH values 7 and 8.5. The initial concentration of As was kept at 100 µM. Results showed that GN adsorbs near 50–70% As, depending on pH, and the reaction kinetics can be described by a pseudo-second-order model. Adsorption efficiency and the rate decreased with increasing alkalinity, indicating competition for sorption sites between AsV and OH− on GN. Calcite and HA showed no efficiency toward the adsorption of As within the studied time range. Slight As adsorption efficiency (≈ 14%) by kaolinite was observed at pH 5.5. In all studied pH values, the presence of HA, kaolinite, and calcite significantly inhibited the efficiency and rate of As removal by GN. Limited As adsorption in the presence of HA is probably due to the blockage of GN reactive surface sites by HA. In a system containing kaolinite and GN, the overall As removal rate was controlled by the lowest adsorbent. Interaction effects between kaolinite and calcite, calcite and HA, and kaolinite and HA on the removal of As were statistically insignificant.