Sequential recovery of Cu(II), Cr(III), and Zn(II) from electroplating sludge leaching solution by an on-line biosorption method with dosage controlling

Hydrometallurgy leaching is a common method used to recycle heavy metals from electroplating sludge , but the subsequent separation of heavy metals from the complex leaching solution is difficult. In this study, Cu(II), Zn(II), and Cr(III) were sequentially recycled from electroplating sludge by an on-line biosorption method with dosage controlling. The results showed that the three metals mainly existed in their labile forms and could be leached by HNO 3 . A series of amine-modified bagasse biosorbents were prepared, and diethylenetriamine-modified sorbent was chosen and fixed in a column to remove heavy metals from the leaching solution. Sorbent dosage experiments showed Cu(II) was recycled exclusively at a dosage of 1.5 g/L, while Zn(II) and Cr(III) were recycled simultaneously at a dosage of 3.8 g/L when treating 800 mL of a leaching agent containing 13.4, 9.9, and 7.1 mg/L of Cu, Zn, and Cr. A linear relationship between the dosage and amount of adsorbed metal ions was obtained. The XPS results illustrated that the column had an adsorption affinity order of Cu(II)>Zn(II), Cr(III)≫Ca(II), Mg(II). Cu(II) was enriched in the foot layer, and Zn(II) and Cr(III) were enriched in the middle layer of the column, while co-ions could not be absorbed. According to these results, Cu(II), Zn(II), and Cr(III) could be sequentially recycled by using these columns in-series.