Preparation and Characterization of Mn0.4Zn0.6Fe2O4 Nanoparticles Supported
on Dead Cells of Yarrowia lipolytica as a Novel and Efficient Adsorbent/Biosorbent Composite for the
Removal of Azo Food Dyes: Central Composite Design Optimization Study
The
removal of hazardous dyes is of great importance to making healthy
and drinkable water. Here, a new ferromagnetic composite based on
Mn0.4Zn0.6Fe2O4 nanoparticles
(NPs) supported on dead Yarrowia lipolytica ISF7 (D-YL-ISF7) was prepared. Nanoparticle aggregation was inhibited
using D-YL-ISF7, which causes the availability of more active sites.
The dead D-YL-ISF7-supported Mn0.4Zn0.6Fe2O4 nanoparticles (NPs) were characterized by Fourier
transform infrared (FT-IR), X-ray diffraction (XRD),
field-emission scanning electron microscopy (FESEM), high-resolution
transmission electron microscopy (HRTEM), energy dispersive X-ray (EDX), Brunuaer–Emmett–Teller (BET),
and vibrating sample magnetometer (VSM) analysis and used as robust
adsorbents/biosorbents to simultaneously remove tartrazine (TA) and
ponceau 4R (P4R) azo food dyes in their binary solution. First-order
derivative spectrophotometry was implemented for the simultaneous
analysis of dyes in binary mixtures. Central composite design (CCD)
was used to evaluate the influence of pH, sonication time, Mn0.4Zn0.6Fe2O4-NPs-D-YL-ISF7
mass, and initial TA and P4R concentrations on the efficiency for
the removal of the studied dyes. At optimum conditions (pH 2.0, sonication
time 5 min, Mn0.4Zn0.6Fe2O4-NPs-D-YL-ISF7 mass 0.015 g, TA concentration 12 mg L–1 and P4R concentration 16 mg L–1), high removal
efficiencies (>99.0%) were obtained for TA and P4R dyes, reasonably
well predicted by the model. The CCD allowed the optimization and
the scale-up of the process, which presented a good correlation between
large and small scales. Adsorption isotherm data fitted well to the
Langmuir model. Under ultrasound, the Langmuir adsorption capacity
of Mn0.4Zn0.6Fe2O4-NPs-D-YL-ISF7
was obtained to be 90.827 mg g–1 for TA and 101.461
mg g–1 for P4R. A pseudo-second-order reaction model
was chosen for kinetic study.