Selective sorption of PAHs from TX100 solution by resin SP850: effects of TX100 concentrations and PAHs solubility

Efficient removal of polybrominated diphenyl ethers from soil washing effluent by dummy molecular imprinted adsorbents: Selectivity and mechanisms

Surfactant enhanced elution is an effective method for removing hydrophobic organic pollutants from soils. The key to the development of leaching technology is selective removal of targeted pollutants in soil washing effluent and recycling of surfactant solutions. In this study, a molecular imprinting technique was applied to selectively sorb polybrominated diphenyl ethers (PBDEs) in soil washing effluent. The novel molecular imprinted polymers (MIPs) using different template molecules were synthesized by precipitation polymerization. Adsorption behaviors and mechanisms of MIPs were studied through experiments and theoretical calculations. The results show that 4-bromo-4'-hydroxybiphenyl and toluene can be effective imprinting molecule for MIPs synthesis. The maximal adsorption capacity of selected dummy molecular imprinted polymer (D₁-MIP) was 1032.36 µmol/g, and that of part molecular imprinted polymer (P-MIP) was 981.13 µmol/g. Their imprinting factors in 5 PBDEs adsorption ranged from 2.13 to 5.88, the recovery percentage of Triton X-100 can reach 99.09%, confirming the feasibility of reusing surfactant. Various PBDEs could be removed by MIPs, and Quantitative Structure Property Relationship analysis revealed that PBDEs' molecular volume, planarity, polarity, and hydrophobicity have major influences on their adsorption performance. DFT calculation revealed that Van der Waals force and hydrogen bonding played important roles during selective adsorption. These results can provide effective theoretical guidance for surfactant enhanced soil elution in practical engineering applications.

Insight into the application of magnetic molecularly imprinted polymers in soil-washing effluent: Selective removal of 4,4'-dibromodiphenyl ether, high adaptivity of material and efficient recovery of eluent

Soil washing techniques can effectively remove soil polybrominated diphenyl ethers (PBDEs), but further removal of PBDEs from washing effluent is disrupted by environmental factors and coexisting organic matter. Hence, this work prepared novel magnetic molecularly imprinted polymers (MMIPs) to selectively remove PBDEs in soil washing effluent and recycling surfactants, with Fe₃O₄ nanoparticles as the magnetic core, methacrylic acid (MAA) as the functional monomer, and ethylene glycol dimethacrylate (EGDMA) as the cross-linker. Later, the prepared MMIPs were applied to adsorb 4,4'-dibromodiphenyl ether (BDE-15) in Triton X-100 soil-washing effluent and characterized by scanning electron microscopy (SEM), infrared spectrometry (FT-IR), nitrogen adsorption and desorption experiments. According to our observations, BDE-15 equilibrium adsorptions on dummy-template magnetic molecularly imprinted adsorbent (D-MMIP, 4-bromo-4'-hydroxyl biphenyl as template) and part-template magnetic molecularly imprinted adsorbent (P-MMIP, toluene as template) were reached within 40 min, and their equilibrium adsorption capacities were 164.54 μmol/g and 145.55 μmol/g, respectively, with imprinted factor α > 2.03, selectivity factor β > 2.14, and selectivity S > 18.05. MMIPs exhibited good adaptability to pH, temperature, and cosolvent. Our Triton X-100 recovery rate reached as high as 99.9%, and MMIPs maintained a more than 95% adsorption capacity after being recycled five times. Our results offer a novel approach to selectively remove PBDEs in soil-washing effluent, with efficient recovery of surfactants and adsorbents in soil-washing effluent.