Selective and high efficient removal of Hg2+ onto the functionalized corn bract by hypophosphorous acid

A novel sorbent (HPACB) was prepared by functionalized corn bract with hypophosphorous acid and applied to selectively remove Hg 2+ from aqueous solution. The HPACB was analyzed by Fourier transform infrared spectroscopy, scanning electron microscope and X-ray photoelectron spectroscopy. The adsorption properties of HPACB for Hg 2+ were studied by batch experiments. The results showed that HPACB presented an excellent selectivity for Hg 2+ from the competitive ions solution, viz. Cu 2+ , Cd 2+ , Co 2+ , Ni 2+ and Zn 2+ . The isotherms and kinetics of adsorption process were well fitted to Langmuir and pseudo-second-order model, respectively. The results indicated that the adsorbing process was monolayer adsorption and the rate-limiting step was chemical sorption . The theoretical maximum adsorption capacity of HPACB for Hg 2+ estimated from Langmuir model was 1293.71 mg/g, which was close to the experimental results. Moreover, the adsorbent can be easily regenerated and the removal rate was still higher than 92% after three cycles. The XPS analysis indicated that the complexation between Hg 2+ and P O/P OH was the main adsorption mechanism during the adsorption process, and the ion exchange also played an important role. These results suggested that HPACB was a potential sorbent for selective removal of Hg 2+ from wastewater.