Abstract
Three-dimensional (3D) urchin-like MnO2@poly (sodium 4-styrene sulfonate) (PSS)/poly (diallyl dimethylammonium chloride) (PDDA)/PSS particles were prepared via the layer-by-layer (LBL) assembly of polyelectrolytes for the extraction of Zn2+ from alkaline media. The adsorption performance of Zn2+ on MnO2, MnO2@PSS/PDDA/PSS, and MnO2@(PSS/PDDA)3/PSS was investigated in batch experiments. The adsorption of Zn2+ on MnO2@PSS/PDDA/PSS has been studied under various conditions, such as initial Zn2+ concentration, adsorbent dosage, the solution’s pH, and reaction time. The Zn2+ adsorption process is well represented by the pseudo-second-order kinetic model, and the equilibrium data fit the Freundlich isotherm well. MnO2@PSS/PDDA/PSS also showed high efficiency for Pb2+ and Cu2+ removal from slightly alkaline water. Thus, our research provides a deep insight into the preparation of 3D manganese oxides with polyelectrolyte films for the extraction of heavy metal ions, such as Pb2+, Cu2+, and Zn2+, from slightly alkaline wastewater.
Highlights
(LBL) assembly of polyelectrolytes for the extraction of Zn2+ from alkaline media
Many studies have been published related to the removal of Zn2+ from acidic [20,21] to neutral wastewater; little information is available for Zn2+ adsorption in slightly alkaline water [22,23]
3D urchin-like MnO2 @PSS/PDDA/PSS particles were prepared via the layer-by-layer (LBL) assembly of polyelectrolytes on MnO2 for the extraction of Zn2+ from alkaline media
Summary
The dissolved phase of heavy metals, such as Pb2+ , Cu2+ , and Zn2+ , in wastewater has become a matter of increasing concern due to their great transferability and bioavailability, as well as their severe cytotoxicity [1–3]. Exploring efficient and cost-effective methods for heavy metal treatment is in demand, especially in developing countries. Various materials, such as adsorbents [9,10], ion exchange resins [11,12], chemical precipitation agents [13,14], electrochemical anodes [15] and membranes [16,17] have been used to remove heavy metal ions [18]. Manganese oxide (MnO2 ) has been extensively reported as an efficient scavenger of many heavy metals, due to their unique physical and chemical properties, with the controllable tuning of structure [24–26], while it is still important to improve their stability and chemical activity. The derivatizing process of urchin-like MnO2 surfaces with macromolecular components noticeably enhances their affinity for heavy metals. Different experimental conditions affecting the uptake of Zn2+ were investigated, and the experimental data were fitted with various models to further understand the adsorption mechanisms
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