Magnetic Porous Polymers Prepared via High Internal Phase Emulsions for Efficient Removal of Pb²⁺ and Cd²⁺

Magnetic porous polymers (MPPs) were successfully fabricated by a facile strategy of the high internal phase emulsions (HIPEs) technique. The microstructure, chemical composition, and magnetic properties of the MPPs were characterized. Impregnated with poly­(styrene-divinylbenzene), stabilized by the amine-functionalized Fe₃O₄ nanoparticles (Fe₃O₄–NH₂), the as-prepared MPPs with rich pore hierarchy were employed to removal Pb²⁺ and Cd²⁺ from aqueous solution. The MPPs display outstanding removal capacities toward Pb²⁺ (257 mg/g) and Cd²⁺ (129 mg/g) within 15 min, and the encapsulated Fe₃O₄–NH₂ nanoparticles endow the MPPs with the ability of magnetic separation (30.15 emu/g). Additionally, the results indicate that the adsorptions of Pb²⁺ and Cd²⁺ are strongly dependent on pH and ionic strength, demonstrating that the interactions of Pb²⁺ and Cd²⁺ were mainly dominated by outer-sphere surface complexation and electrostatic attraction. The adsorption process is revealed by thermodynamic parameters to be spontaneous and endothermic. Further study demonstrates that the adsorption is involved in ion-exchange and cation−π interactions (between heavy metals and aromatic ring) on the surface of MPPs. Thus, feasible preparation of the MPPs with high adsorption capacities, excellent regeneration, and easy separation properties opens a new expectation in the potential application for engineering

Biochar Derived from Sawdust Embedded with Molybdenum Disulfide for Highly Selective Removal of Pb²⁺

Surface interactions between the adsorbents and heavy metal ions play an important role in the adsorption process, and appropriately decorating the material’s surface can significantly improve the removal capacity of the adsorbents. So, the objective of this study is to modify biochar by coating with molybdenum disulfide (MoS₂) for enhancing the adsorption of Pb²⁺. The biochar pyrolyzed at 600 °C was chosen as the base to combine the flowerlike MoS₂ (MoS₂@biochar) by solvothermal reaction, in which the abundant S-containing functional groups may promote the elimination of Pb²⁺. The prepared MoS₂@biochar exhibits excellent adsorption capacity (189 mg/g) to Pb²⁺ in water solution. The adsorption of Pb²⁺ maintains a high level under the circumstance of coexisting ions (Mg²⁺, Ca²⁺, Co²⁺, and Cd²⁺), suggesting the high selectivity for Pb²⁺. The adsorption mechanism of Pb²⁺ on MoS₂@biochar is mainly ascribed to the inner-sphere surface complexation, in particular, metal–sulfur chemical complexation. The easily recycled MoS₂@biochar still has high adsorption capacity for Pb²⁺. This work demonstrates that the MoS₂@biochar is an excellent candidate of adsorbent for Pb²⁺ removal

Fabrication of Core–Shell CMNP@PmPD Nanocomposite for Efficient As(V) Adsorption and Reduction

Here, we prepared novel carboxyl-functionalized Fe₃O₄ nanoparticles (CMNPs) coated with poly­(m-phenylenediamine) (CMNP@PmPDs) without complicated premodification procedures. The CMNP@PmPDs show well-defined core–shell structures and combine both the facile separation properties of magnetic particles and the extraordinary adsorption performance of polymers. The CMNP@PmPDs were employed to investigate the influence of various environmental factors (initial pH, ionic strength, etc.) on the removal of As­(V) through batch experiments. The CMNP@PmPDs display much better As­(V) adsorption performance than the CMNPs, and the adsorption capacity is enhanced from 51.2 mg g^–1 to 95.2 mg g^–1. The CMNP@PmPDs exhibit high magnetization (∼46.7 emu g^–1), indicating their easy separation under an external magnetic field in practical applications. The major reaction pathway involving the reduction of As­(V) to As­(III) was identified by X-ray photoelectron spectroscopy (XPS) analysis. The removal mechanisms can be explained by the adsorption of As­(V) on protonated imino and carboxyl groups via electrostatic attraction, which is then reduced to As­(III) by amine groups. This study demonstrates the potential application of CMNP@PmPDs as a low-cost and effective remediation strategy for the removal of As­(V) from wastewater