Uptake of arsenite by synthetic layered double hydroxides.
Two types of layered double hydroxides (LDHs), hydrotalcite and hydrocalumite with different composition of layers and interlayers were investigated for the removal of arsenite from solutions. The kinetics study showed that anion exchange process was very fast and apparently attained a steady-state in the range of 8-16 h. Arsenite removal was found to be 87.5% and 83.6% with the nitrate forms of hydrotalcite and hydrocalumite, respectively. Layered double hydroxides synthesized at room temperature showed higher uptake than those synthesized by hydrothermal method due to small crystal size (high surface area) of the former. As expected, calcined hydrotalcite showed higher uptake than uncalcined carbonate form of hydrotalcite. The uptake process was anion exchange in hydrotalcite-type LDH as confirmed by X-ray diffraction (XRD) and scanning electron microscopy (SEM) but possibly some dissolution-reprecipitation occurred with hydrocalumite-type LDH.
Grover
Kanchan
K
Materials Research Institute, The Pennsylvania State University, University Park, PA 16802, USA.
Komarneni
Sridhar
S
Katsuki
Hiroaki
H
D000536:Aluminum Hydroxide / Q000737:chemistry; D018053:Arsenites / Q000032:analysis*; D006878:Hydroxides / Q000737:chemistry*; D007474:Ion Exchange; D008276:Magnesium Hydroxide / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000032:analysis*; D018508:Water Purification / Q000379:methods*; D014961:X-Ray Diffraction
D018053:Arsenites; D006878:Hydroxides; D014874:Water Pollutants, Chemical; C010467:hydrotalcite; D000536:Aluminum Hydroxide; C015001:arsenite; D008276:Magnesium Hydroxide