A B S T R A C T
Spinel ferrite MFe2O4, (M=Co, Ni, Cu and Zn) nanoparticles are prepared by
Microwave Combustion Method (MCM). For as-prepared, Rietveld analysis of X-ray
diffraction patterns indicates the formation of single phase for NiFe2O4 and ZnFe2O4, while
new (α-Fe2O3 and CuO) phases precipitate for CoFe2O4 and CuFe2O4, respectively, meanwhile
the crystallite size ranges between 40-51 nm. After annealing, a single phase is obtained for all
spinel ferrite system, CuFe2O4 transforms from tetragonal structure to cubic structure after
annealing. Magnetisation-field (M-H) curves reveal ferromagnetic order for CoFe2O4, NiFe2O4
and CuFe2O4, while a superparamagnetic behaviour is observed for ZnFe2O4, and the magnetic
properties (saturation magnetization, remanence and coercivity) are found to slightly change
after annealing, except CuFe2O4, due to phase transformation from tetragonal to cubic and grain growth; both saturation magnetisation and remanence decrease from 25.97 to 1.685 emu/g and 13.93 to 2.635 ×10ିଷ emu/g, respectively. Interestingly, after annealing CuFe2O4 shows a
superparamagnetic behaviour. SEM observations show particles with undefined shape and
broad particle size distribution. It can be concluded that MCM is very suitable to prepare
method to obtain single phase of NiFe2O4 and ZnFe2O4. The obtained spinel ferrite
nanopowders as prepared by MCM and after annealing are used for up take tests toxic metal
ions removal from wastewater including Cadmium (Cd2+) and lead (Pb2+) were investigated.
The adsorption was carried out in batch mode by adding 10, 20 and 30 mg of MNPs to 25 ppm
solutions of Cd2+ and Pb2+ ions in 50 ml Erlenmeyer flask at pH equal 2. The maximum
adsorption capacities are found for 10 mg compared to higher concentrations; i.e. 20 and 30
mg. the highest amount of 30 mg has the lowest adsorption capacities. It is observed that the
adsorption capacity is greater for Cd2+ than Pb2+; 69.4 and 47.1 mg/g, respectively. Then lower
amount of MNPs is opted to investigate, the value of adsorption capacities almost double for
Cd2+ (120-1220 mg/g compared to 10 mg (52-60) mg/g, while no considerable effect has been
noticed for Pb2+. Moreover, the adsorption capacity is influenced by pH; a basic media is found
to be better than acidic for both Cd2+ and Pb2+, but Pb2+ shows a much higher capacity (almost
double).