posted on 2024-01-01, 17:03authored byRattanawadee
Ploy Wijitwongwan, Makoto Ogawa
A layered double hydroxide (LDH) composed of Ni2+ and
Fe3+ with a Fe3+/(Ni2+ + Fe3+) ratio of 0.05, which is not commonly available, was successfully
prepared by coprecipitation from an aqueous solution of glycerol containing
nickel nitrate and iron nitrate. Precipitation using NaOH as a precipitating
agent at room temperature or 120 °C under hydrothermal conditions
gave products with micrometer-sized aggregates of nanometer-sized
unshaped particles, while that using urea yielded LDHs with a foam-like
porous architecture composed of platy particles with a size of 100–300
nm. The products were examined to remove Cr(VI) from an acidic (pH
= 3) aqueous solution of K2Cr2O7 by
adsorption and photocatalytic reduction. The foam-like porous NiFe-LDH
exhibited the highest adsorbed amount (122 mg g–1) and rate (0.017 g mg–1 min–1) in the dark and the highest rate (0.012 min–1) of photocatalytic Cr(VI) reduction among the NiFe-LDHs prepared
in the present study, which can be explained as a positive effect
of the foam-like porous architecture. These performances were superior
to those of other reported LDHs, showing the importance of the composition
and the particle morphology to boost the removal of Cr(VI).