Hydrate-Based Method to Remove Cr(III) and Ni(II) in Chromium Hydroxide Sulfate and Nickel Sulfate Hexahydrate Solutions

Abstract

The hydrate-based method provides a potential method to remove heavy metal ions. In this work, the phase equilibrium conditions of methane hydrate in chromium hydroxide sulfate solutions and nickel sulfate hexahydrate solutions were first measured. The results suggested that the addition of both chromium hydroxide sulfate and nickel sulfate hexahydrate inhibited methane hydrate formation and acted as thermodynamic inhibitors. In addition, the removal efficiencies of both chromium hydroxide sulfate and nickel sulfate hexahydrate were also measured by forming methane hydrate at different hydration time. The results suggested that the chromium hydroxide sulfate removal efficiency reached 82.1% with a 23.7% yield of melting water at 274.2 K with a hydration time of 1 h, while nickel sulfate hexahydrate removal efficiency reached 67.5% with 68% yield of melting water at 274.2 K.

Investigation on the Removal Performances of Heavy Metal Copper (II) Ions from Aqueous Solutions Using Hydrate-Based Method

“…According to our previous work [ 39 , 40 ], the autoclave and the relative connections are cleaned three times, and then the prepared copper (II) sulfate solution was injected into the autoclave. Then, the glycol bath was set to the experimental temperature, and maintained for 30 min.…”

“…For example, Zhao and their co-works first performed heavy metal separation experiments from aqueous solutions using a hydrate-based method [ 38 ]. In our previous work, we have also measured the removal efficiencies of heavy metal chromium and nickel form their aqueous solutions using a hydrate-based method [ 39 , 40 ].…”