Removal and recovery of copper(II), chromium(III), and nickel(II) from solutions using crude shrimp chitin packed in small columns

Shrimp shell wastes from Penaeus marginatus were demineralized by dilute hydrochloric acid in small columns to yield shrimp chitin, without removal of proteins. Ninety-six percent of calcium was efficiently removed by this column method. The two biosorbents, prepared shrimp chitin and purchased crab chitosan, were tested for their copper (Cu)(II), chromium (Cr)(III), and nickel (Ni)(II) removal and recovery efficiencies from aqueous metal solutions with concentrations ranging from 20-100 mg/L. The shrimp chitin demonstrated remarkable Cu(II) and Cr(III) collecting ability of over 95% and 96%, respectively, comparable to the best metal chelating biopolymer chitosan, whose Cu(II) and Cr(III) removal abilities under the same conditions were over 98% and 93%, respectively. However, the Ni(II) removal efficiencies of shrimp chitin were lower (44-70%) than those of crab chitosan (82-99%). Likewise, the recovery efficiencies of shrimp chitin for Ni(II) were lower (80-98%) than those of crab chitosan (83-100%). Cu(II) and Cr(III) ion recovery percentages by 0.1M EDTA for shrimp chitin were significantly higher than those of crab chitosan, although the recovery percentages of Cr(III) were low for both biosorbents and need further investigation. A preliminary test on the collecting ability of shrimp chitin on Cu(II) present in electroplating baths rinsing waters gave encouraging results. The shrimp chitin removed 92-96% Cu(II) from copper pyrophosphate and acid copper bath rinsing water.