Morphological behaviors of brushite/vivianite nanocomposites and their potency for Se(IV) and Cd(II) removal from aqueous solutions

Abstract Designing of high efficient composition for heavy metal removal from solutions has become a pivotal demand to keep people's health level. In this issue, nanocomposites containing different contributions of brushite and vivianite phases were fabricated using a facile technique. The obtained compositions were characterized using XRD, TEM, FESEM, and XPS. Upon TEM investigation, it was shown that brushite was formed as ellipsoidal particles with dimensions of 47.6 × 50.1–76.2 × 107.3 nm, while vivianite was formed as elongated fibers with diameters of 18.2 nm and lengths over 270 nm. The surface morphology of 0.2Br/0.8Viv seems to be multilayered rectangles of brushite stacked in a cauliflower configuration with lengths of 4.8 μm and decorated with vivianite fluffy grains with dimensions of 0.8–1.6 μm. Moreover, the maximum height of roughness developed from 262.7 to 373.3 nm for 1.0Br/0.0Viv and 0.2Br/0.8Viv, respectively. In addition, the superficial charges of the compositions were estimated using Zeta potential and displayed a growth from −20.8 ± 4.91 to −27.4 ± 6.26 mV from pure brushite to vivianite, respectively. Furthermore, the removal behavior of Se(IV) and Cd(II) from aqueous solutions was conducted. It was shown that the highest removal efficiency upon variation of contact time was saturated after 6 h and after 24 h, reached around 83.2, 87.6, 89.5, 91.3, 95.0 and 98.1% for Se(IV) and 86.8 to 87.7, 91.5, 93.7, 96.0 and 98.5% for Cd(II) upon compositions of for 1.0Br/0.0Viv, 0.8Br/0.2Viv, 0.6Br/0.4Viv, 0.4Br/0.6Viv, 0.2Br/0.8Viv and 0.0Br/1.0Viv, respectively. The obtained behaviors of these nanocomposites encourage their utilization for numerous water filtration applications.