**4. Conclusion**

Nanomagnetic absorbent (NA) based on calcium alginate along with gammamaghemite nanoparticles were synthesized in situ and applied for the removal of metals present in industrial wastewater. The NA presented, predominantly, spherical morphology, with homogeneous distribution of the elements iron and calcium, both on the internal and external surfaces of the NA particles, and responded to the stimulus of a magnet. The XRD diffractogram demonstrated that the synthesized magnetic material was maghemite. The transmission electron microscopic images proved that the maghemite particles had diameters smaller than 20 nm. The NAs were good adsorbents of the metals from the wastewater. The adsorption equilibrium was achieved in 1 hour at pH of 6.5. By using 300 mg of NA, it was possible to remove simultaneously 60.5% of Ni (II) and 56.6% of Mn (II). Based on the results, we can propose that the adsorption mechanism of the metals occurred by exchange of Ca2 + ¬ ions (crosslinker) with Ni2+ and Mn2+ ions present in the wastewater.
