Effective Removal of Pb2+ from Aqueous Solution Using Magnetic Mesoporous Silica Prepared by Rubidium-Containing Biotite Leaching Residues and Wastewater

Abstract

The rubidium leaching process from biotite generates a large amount of waste materials that should ideally be reused for heavy metal ion adsorption so as not to create environmental problems. Ferric oxide/mesoporous silica (FO/MS) is a novel adsorbent used for heavy metal ion removal with a high removal capacity of Pb2+ (143.47 mg/g within 60 min) that was prepared for the first time by comprehensively utilizing both rubidium-containing biotite leaching residues and wastewater. The incorporation of mesoporous silica prepared by leaching residues could provide a porous framework and channel for depositing ferric oxide. Mesoporous channels have a high specific surface area that improves the adsorption activity and capacity of the material. Additionally, in a pH study, the adsorptive thermodynamic and dynamic analyses, as well as XPS and FTIR analyses, verified the adsorption properties involved in surface complexing and electrostatic binding. The surface complexation process mainly was the interaction of Pb2+ with surface hydroxyl groups. This work provided a novel and effective strategy for preparing waste solid-based heavy metal ion adsorption and expanded technologies for treating acid leaching wastewater. The adsorbents of FO/MS with a high Pb2+ adsorption capacity suggested that, compared with other materials, it is a suitable remediation material for Pb2+ contaminated water.

Efficient Leaching of Rubidium from Biotite by Ion Exchange without Destroying the Lamellar Crystal Structure

“…The previous work used H 2 SO 4 to extract Rb from biotite under the conditions of 4 mol/L H 2 SO 4 at a liquid−solid ratio of 4:1 (mL/g), which resulted in a high Rb leaching efficiency of 95.6%. 24 However, the consumption of H 2 SO 4 was relatively high in the leaching process. Hence, the enhanced effect of cation exchangers on L e (Rb) was investigated under a lower dosage of 1 mol/L H 2 SO 4 , as listed in Table 1 for tests from No.…”

“…The previous work used H 2 SO 4 to extract Rb from biotite under the conditions of 4 mol/L H 2 SO 4 at a liquid–solid ratio of 4:1 (mL/g), which resulted in a high Rb leaching efficiency of 95.6% . However, the consumption of H 2 SO 4 was relatively high in the leaching process.…”

“…Under the optimal leaching conditions, the leaching rate of Rb was 94%. However, due to the consistent leaching behavior of Ca 2+ , Mg 2+ , Fe 3+ , Al 3+ , and Rb + in acid leaching solution, the subsequent purification and impurity removal process is complicated . The alkaline leaching process has the limitations of a large amount of alkali consumption, high viscosity of leaching solution, and high concentration of silicon in the leaching solution .…”

“…Under the optimal conditions, the L e (Rb) from Rb-BB reached 95.6%. Compared with our previous direct H 2 SO 4 leaching process (DSL1) involving 4 mol/L H 2 SO 4 and a liquid−solid ratio of 4:1 (mL/g), 24 and DSL2 involving 5.52 mol/L H 2 SO 4 and a liquid−solid ratio of 3:1 (mL/g), 48 in this study 56.63 and 54.73% H 2 SO 4 consumption was effectively saved, respectively. As shown in Table 6, this enhanced process can efficiently extract Rb without destroying the mica structure and effectively reduce the consumption of acid.…”

“…However, due to the consistent leaching behavior of Ca 2+ , Mg 2+ , Fe 3+ , Al 3+ , and Rb + in acid leaching solution, the subsequent purification and impurity removal process is complicated. 24 The alkaline leaching process has the limitations of a large amount of alkali consumption, high viscosity of leaching solution, and high concentration of silicon in the leaching solution. 46 Therefore, it is of great practical significance to develop an energy-saving and low-emission leaching process.…”