含钙废水资源化制备 W@SA 凝胶及其Pb(II)吸附性能

In order to recover calcium resource from calcium wastewater and solve the problem of heavy metal pollution, sodium alginate adsorbent (W@SA) was prepared using actual calcium wastewater by a simple synthetic method. Scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), low temperature N₂ adsorption and desorption and Fourier transform infrared (FT-IR) spectroscopy were used to characterize W@SA. Moreover, the adsorption performance of W@SA on Pb(II) was studied and the adsorption mechanism was analyzed. Finally, the purification effect of the synthetic method on actual calcium wastewater was tested. The results reveal that W@SA exhibits a porous structure and abundant hydroxyl and carboxyl groups. W@SA shows a good removal effect of Pb(II). When the initial concentration of Pb(II) is 25 mg/L in wastewater, the removal rate of 99.2% can be achieved after reacting for 25 min. Compared with sodium alginate gel (N@SA) synthesized by conventional calcium source, W@SA maintains 99.0% removal efficiency. Ion exchange, electrostatic attraction and inner-sphere complexation are the main mechanisms for W@SA to adsorb Pb(II). The method for synthesizing W@SA by actual calcium wastewater can remove 91.0% of Ca(II) in that wastewater cumulatively, and simultaneously makes the cumulative removal rates of the ammonia nitrogen, the phosphate radical and the COD_Cr in the original calcium wastewater reach 83.2%, 60.8% and 68.1%, respectively. These findings can provide a novel idea for wastewater recycling and the design of sodium alginate adsorbent.