Abstract
The saturated magnetization σ(emu·g-1) was measured for the ferrite sludge formed by two-step treatment with pH adjustment of wastewater containing nickel sulfate. Simultaneously, the concentration of nickel and iron ions in the treated water was measured. The effect of pH adjustment on the above parameters was quantitatively discussed by comparing the two different treatments: conventional and two-step treatments.
The σ of ferrite sludge formed by the two-step treatment with pH adjustment was slightly larger than that by conventional and two-step treatments. XPS measurement of the sludge formed by conventional and two-step treatment with pH adjustment indicated the existence of Ni(OH)2 on the surface of ferrite particles. The measurement after Xe+ sputtering showed that the Ni(OH)2 is present not only on the surface but also in the bulk of the particles formed by conventional treatment. In leached test, the concentration of nickel ion in the elute was lower in order of conventional, two-step and two-step treatment with pH adjustment in relation to Ni(OH)2 on the surface of ferrite particles.
The two-step treatment with pH adjustment stabilizes the sludge and is favorable for steady operation of the ferrite process, industrial utilization of the sludge and good quality of the treated water.
