(254av) Study upon Enhanced Removal of Cu(II), Ni(II), Pb(II), Zn(II), Mn(II), Cr(III) from Polluted Water By Self-Synthetic Struvite Treatment

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Heavy metals existing in the water have brought much concern. The conventional hydroxide precipitation treatment is hard to achieve satisfactory removal efficiency, particularly under situation of low heavy metal concentration. The research has synthesized struvite crystals and utilized the self-synthesized struvite for the enhanced removal of six heavy metals (Cu, Ni, Pb, Zn, Mn, Cr(III)) from solution. The experiments have studied the removal efficiency under pH values from 6.0 to 10.0, and under a series of struvite addition. The research compared the performance of struvite treatment and mere hydroxide precipitation treatment as a control treatment. It was found that struvite treatment was far superior than the control treatment, with residual concentration of six heavy metals from copper to chromium at 0.01, 0.04, 0.00,0.00, 0.13, 0.004mg/L under 2g struvite addition and pH 10.0. For extremely low heavy metal concentration it achieved removal of 99.1%, 97.9%, 99.9%, 98.9%, 96.9%, and 98.3%, which was much higher than that of control treatment (10.5%, 8.7%, 13.2%, 14.1%, 6.7%, and 10.5%). Through XPS and SEM & EDS analysis, it was found the heavy metal hydroxides were precipitated on the struvite surface. Moreover, based on TEM observations, it was found the heavy metal hydroxides had a nucleation and development on the struviteâ??s surface. The heterogeneous nucleation mechanism has been proposed for struvite treatment, which provides relationship of sorption, nucleation, and precipitation of heavy metal hydroxides on struvite surfaces and realize the quantification of the ability of struvite in enhancing heavy metal precipitate formation.