Heavy metal ions can accumulate in the area’s crop harvest, such as rice, via a tight binding with protein. Such binding paves great difficulties to remove heavy metal ions. This study aims to remove cadmium from contaminated rice protein using rhamnolipid biosurfactant together with Pluronic F127/poly (acrylic acid) (i.e., F127/PAA) hydrogels. The two-step consequential washing removed 92% of cadmium in rice protein, making the residual cadmium content below the safety level (<0.2 mg/kg) without impairing the main components and structure of rice protein. Interestingly, the washing by either rhamnolipids or hydrogels failed to effectively remove cadmium, indicating the synergistic effect of the two materials. Mechanistically, rhamnolipids with higher Cd 2+ binding constant compete with protein on binding with cadmium and then deliver it to F127/PAA hydrogels that present highest Cd 2+ adsorptive capability for immobilization. In considering that the F127/PAA hydrogels are reusable, this treatment is low-cost, safe and effective for removal of cadmium from polluted rice products.
Organic matters in wastewater dramatically impaired the removal capability of adsorbents to heavy metal ions , thus greatly limited their applications for real systems. Here we fabricated the F127/PAA hydrogels that could effectively remove Cu 2+ and Hg 2+ from organic wastewater due to their anti-fouling properties against organic matters. The F127/PAA hydrogels performed high swelling ratio and mechanical stress, showing maximum adsorption capacities of Cu 2+ and Hg 2+ at 283.4 and 222.1 mg/g, respectively. For the BSA containing water, the removal ratio of Cu 2+ and Hg 2+ by F127/PAA hydrogels could reach to 94.0% and 70.2%, respectively. For the humic acid containing water, the corresponding data were 89.5% and 72.1%. Besides, five cyclic adsorption–desorptions in humic acid solution and simulated cosmetic wastewater only slightly decreased the removal efficiencies of F127/PAA hydrogels to Cu 2+ and Hg 2+ . Our results suggested the potential application of the F127/PAA hydrogels in treatment of real organic wastewater.
危险品化学品经营许可证（带存储）