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

Abstract

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 6 2.7 m 2 g 21 and 0.063 6 0.007 mL g 21 , respectively. Zero point of charge of AAL is found to be 5.70 6 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 6 8.9 lg L 21 ) has been treated at a breakthrough concentration of 50 lg L 21 of arsenic by using column height of 20 cm (weight of adsorbent: 125 g).

Removal of arsenic from drinking water by batch and continuous electrocoagulation processes using hybrid Al‐Fe plate electrodes

“…There was also no residual iron or aluminum present in the outlet solution, insuring a high arsenic removal efficiency of the produced ferric or aluminum ions (i.e., less metal necessary to dissolve to adsorb or co‐precipitate arsenic ions for all hybrid electrode pairs). The obtained results were in agreement with the literature values .…”

“…The EC reactor with hybrid electrode pairs was operated at Me:arsenic ratios of 14.8–121.2 mol:mol when treated with 150 µg/L of arsenic solution. This indicated that the main chemical reactions occurring during the process was adsorption such as ( ) or FeAsO 4 and coprecipitation such as Fe‐Al hydroxides . Me/As mole ratio for Fe‐Al‐Al‐Fe electrode pairs was obtained for 14.8.…”

“…A variety of treatment techniques has been used for arsenic removal from drinking waters including chemical coagulation, modified chemical coagulation‐filtration, manganese greensand filtration, modified lime softening, adsorption, ion‐exchange, membrane filtration, reverse osmosis, and other techniques . The advantage and disadvantages of main arsenic removal technologies are presented in Table , along with a brief description of how removal efficiency is affected by arsenic concentration and speciation, pH and the presence of other dissolved constituents .…”

Removal of chromium (VI) from aqueous solution using chemically modified corncorb‐activated carbon: Equilibrium and kinetic studies

“…Activated carbon is widely used as an adsorbent due to its high adsorption capacity and cost effectiveness. The adsorption capacity is related to the pore structure and chemical nature of the carbon surface, which in turn, is influenced by the preparation condition [23][24][25][26][27][28][29][30][31][32].…”

Performance of Laterite Soil Grains as Adsorbent in the Removal of Chromium

“…The Cr (VI) state is of especial interest because of its noxious. Thermodynamically stable chromate (CrO 4 2-) and dichromate (Cr 2 O 7 2-) anions which vary over a wide pH range are the usual hexavalent chromium wastes discharged into the surroundings. Cr (VI) compounds are noxious which causes lung cancer, as well as kidney, liver and skin damage in human beings (Kousalya, Gandhi, and Meenakshi 2010).…”