Removal of Pb(II) ions from aqueous solution using complexation-ultrafiltration

The investigation of the binding ability between sodium dodecyl sulfate and Cu (II) in urban stormwater runoff

The simultaneous presence of heavy metals and surfactants in runoff induces complexation and ecological harm during migration. However, interactions between these pollutants are often overlooked in past studies. Thus, investigating heavy metal-surfactant complexes in runoff is imperative. In this work, Cu (II) and sodium dodecyl sulfate (SDS) were selected to investigate the interaction between heavy metals and surfactants due to the higher detected frequency in runoff. Through 1H NMR and FTIR observation of hydrogen atom nuclear displacement and functional group displacement of SDS, the change of SDS and Cu (II) complexation was obtained, and then the complexation form of Cu (II) and SDS was verified. The results showed that solution pH values and ionic strength had significant effects on the complexation of Cu (II). When the pH values increase from 3.0 to 6.0, the complexation efficiency of SDS with Cu (II) increased by 12.12% at low concentration of SDS, which may be attributed to the excessive protonation in the aqueous solution at acidic condition. The increase of ionic strength would inhibit the complexation reaction efficiency by 19.57% and finally reached the platform with concentration of NaNO3 was 0.10 mmol/L, which was mainly due to the competitive relationship between Na (I) and Cu (II). As a general filtering material in stormwater treatment measures, natural zeolite could affect the interaction between SDS and Cu (II) greatly. After the addition of SDS, the content of free Cu (II) in the zeolite-SDS-Cu (II) three-phase mixed system was significantly reduced, indicating that SDS had a positive effect on the removal of Cu (II) from runoff. This study is of great significance for investigating the migration and transformation mechanism of SDS and Cu (II) in the future and studying the control technology of storm runoff pollution.

Green complexation for heavy metals removal from wastewater by Keggin-polyoxometalates enhanced ultrafiltration

The presence of heavy metals in wastewater has become a serious issue and a global concern for the environment and public health with rapid progress of modern textile industry. To minimize the health risks of heavy metals their complexation to a chelating agent constitute a promising process using membrane separation. We highlight for the first time the use of Keggin type-polyoxometalates (PW₁₂) as complexing agent to eliminate heavy metals from synthetic textile wastewater. Indeed, filtration experiments were performed through the ultrafiltration organic regenerated cellulose membrane (3KDa). Effects of pressure (1-2.5 bar), PW₁₂ concentration (10-50 mg·L^-1), salt concentration (10^-4-2 M) and pH value (2-12) on cadmium (Cd) and copper (Cu) removal were regularly explored. Experimental data showed that the addition of PW₁₂ improves metal removal efficiency (up to 90%). The addition of NaCl salt significantly decreases the metals retention to 42%. The retention drop is probably due to the competition between Na+ and metals on complexation same negative sites of the PW₁₂ and to the electric double-layer compressing. 2⁴ full factorial design has been used to evaluate the most influencing parameters. The results obtained revealed that the maximum metal retention was 99% for both Cd and Cu.