Metal phosphates
are efficient adsorbent materials for heavy elements
present in industrial effluents because of their promising properties.
Hexachromium ions are among the most dangerous contaminants owing
to their harmful properties and non-degradability. Accordingly, the
present work offers a simplified study of the preparation of bimetallic
phosphate materials from nickel cobalt phosphate (NiCo-Ph) based on
the sol–gel method in an equimolar ratio. Characterization
of the bulk, crystal phase, texture profile, and nanosize of NiCo-Ph
was carried out using various techniques such as Fourier transform
infrared spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy,
nitrogen adsorption–desorption isotherm measurements, field
emission scanning electron microscopy, transmission electron microscopy,
and Raman spectroscopy. In this regard, the adsorption performance
of NiCo-Ph was exemplified through six batch experiments, elucidating
the impacts of the sorbent dose, initial concentration of pollutants,
sorption time, temperature, pH, and shaking rate. According to UV/vis
spectrophotometry measurements and their related calculations of NiCo-Ph,
the maximum removal efficiency (RE %) of 92% and adsorption capacity
(
q
m
) of 37 mg/g were achieved at pH =
6, a dose of 5.0 g/L, 100 mg/L of [Cr(VI)], 300 rpm, adsorption time
of 60 min, and 298 K. Monte Carlo simulations were also carried out
to correlate the experimental data with theoretical calculations that
provided a higher negative value (−911.62 kcal mol
–1
) for the adsorption energy of Cr(VI) in acidic medium. The adsorbent
NiCo-Ph prepared by this direct method is therefore recommended for
the quantification of Cr(VI) under slightly acidic solutions and at
room temperature, which can maintain its efficiency even up to six
cycles.