The removal of arsenate from water using iron-modified diatomite (D-Fe): isotherm and column experiments

• Published in: Environmental science and pollution research international 2014, Vol.21 (1), p.495-506
• Main Authors: Pantoja, M. L., Jones, H., Garelick, H., Mohamedbakr, H. G., Burkitbayev, M.
• Format: Article
• Language: English
• Subjects: Adsorbents; Adsorption; Affinity; Aquatic Pollution; Arsenates; Arsenates - analysis; Arsenates - chemistry; Arsenic; Arsenic content; Arsenic removal; Atmospheric Protection/Air Quality Control/Air Pollution; Bioremediation; Competition; Diatomaceous earth; Diatomaceous Earth - chemistry; Drinking water; Earth and Environmental Science; Ecotoxicology; Environment; Environmental Chemistry; Environmental Health; Experiments; Hydroxides - chemistry; Ions; Iron; Iron - chemistry; Isotherms; Laboratories; pH effects; Phosphates; Phosphates - chemistry; Research Article; Studies; Toxicity; Waste Disposal, Fluid - methods; Waste Water Technology; Water Management; Water Pollutants, Chemical - analysis; Water Pollutants, Chemical - chemistry; Water pollution; Water Pollution Control; Water Purification - methods
• ISSN: 0944-1344; 1614-7499
• DOI: 10.1007/s11356-013-1891-7

Iron hydroxide supported onto porous diatomite (D-Fe) is a low-cost material with potential to remove arsenic from contaminated water due to its affinity for the arsenate ion. This affinity was tested under varying conditions of pH, contact time, iron content in D-Fe and the presence of competitive ions, silicate and phosphate. Batch and column experiments were conducted to derive adsorption isotherms and breakthrough behaviours (50 μg L −1 ) for an initial concentration of 1,000 μg L −1 . Maximum capacity at pH 4 and 17 % iron was 18.12–40.82 mg of arsenic/g of D-Fe and at pH 4 and 10 % iron was 18.48–29.07 mg of arsenic/g of D-Fe. Adsorption decreased in the presence of phosphate and silicate ions. The difference in column adsorption behaviour between 10 % and 17 % iron was very pronounced, outweighing the impact of all other measured parameters. There was insufficient evidence of a correlation between iron content and arsenic content in isotherm experiments, suggesting that ion exchange is a negligible process occurring in arsenate adsorption using D-Fe nor is there co-precipitation of arsenate by rising iron content of the solute above saturation.