Removal of arsenic from synthetic and natural groundwater using acid-activated laterite

• Published in: Environmental progress & sustainable energy Vol. 29; no. 4; pp. 457 - 470
• Main Authors: Maiti, Abhijit, Basu, Jayanta Kumar, De, Sirshendu
• Format: Journal Article
• Language: English
• Published: Hoboken, USA John Wiley & Sons, Inc 01.12.2010; Wiley
• Subjects: Adsorption; Applied sciences; arsenate; arsenic-contaminated groundwater; arsenite; Biological and physicochemical phenomena; Chemical engineering; Exact sciences and technology; Groundwater pollution; Groundwaters; Heat and mass transfer. Packings, plates; laterite; Natural water pollution; Pollution; shrinking core model; sorption; Water treatment and pollution; Second order; Particle size; Transport properties; Arsenic; Arsenates; Adsorption capacity; Modeling; Mass transfer; arsenic-contaminated groundwater; Arsenites; Sorption; arsenate shrinking core model sorption; Mass transfer coefficient; Adsorption; Batchwise; arsenite; Chemical composition; Water pollution; Kinetics; Surface area; Diffusion coefficient; laterite; Fixed bed; Ground water
• ISSN: 1944-7442; 1944-7450; 1944-7450
• DOI: 10.1002/ep.10434

Acid‐activated laterite (AAL) is used to remove arsenic from synthetic and natural groundwater. Physicochemical characteristics of AAL, such as BET (Brunauer‐Emmett‐Teller) surface area, pore volume, pore volume distribution, zero point of charge, and chemical composition, are studied and compared with raw laterite (RL). The BET surface area and pore volume of AAL are obtained as 45.4 ± 2.7 m2 g−1 and 0.063 ± 0.007 mL g−1, respectively. Zero point of charge of AAL is found to be 5.70 ± 0.22. Arsenite and arsenate adsorption on AAL are examined under varying process parameters such as adsorbent dose, contact time, temperature, particle size, initial arsenic concentration, and competitive ions in batch mode. Arsenic adsorption capacity of AAL increases by two‐ to threefold compared with RL. The kinetic data fit better to pseudo‐second‐order model. Transport properties, such as external mass transfer coefficient and effective pore diffusivity of arsenic species, are obtained from shrinking core model fit to experimental kinetic data. Continuous fixed bed column mode adsorption of arsenic on AAL is performed. About 200 bed volume (21 L) of arsenic contaminated groundwater (total arsenic: 378 ± 8.9 μg L−1) has been treated at a breakthrough concentration of 50 μg L−1 of arsenic by using column height of 20 cm (weight of adsorbent: 125 g). © 2010 American Institute of Chemical Engineers Environ Prog, 2010