Controlled fabrication of functionalized nanoscale zero-valent iron/celluloses composite with silicon as protective layer for arsenic removal

[Display omitted] •A controllable preparation method for removing As(III) from wastewater is proposed.•Rod-like NZVI can be distributed evenly orderly on the surface of cotton fibers.•The synergistic effect of cotton fiber, NZVI, silica protective layer effectively improves the removal efficiency.•The adsorption mechanism of FBC on As(III) was systematically proposed. From the perspective of basic human health, arsenic is extremely toxic and highly lethal, which will enter surface water and groundwater through industrial production and eventually enter human beings through the food chain, causing immeasurable harm. Herein, a new composite material, namely NZVI@SiO2@ celluloses (FSC), was successfully synthesized by hydrothermal and reduction methods based on cotton fiber as the carrier, nanoscale zero-valent iron (NZVI) as the active component of arsenic removal and silica as the protective layer. The crystal structure, morphology and chemical elements of the composite were characterized and determined by SEM, XPS, TEM, and XRD techniques. The results demonstrated that rod-like NZVI with the diameter of 50–80nm was distributed evenly on the surface of cotton fiber, and the coating of silica forming a 10–20nm transparent shell can effectively prevent the oxidation of NZVI from losing its effectiveness on the surface. In addition, the optimal adsorption conditions by FSC were investigated by concentration, controlling pH value, interfering ions and temperature. The obtained results show that the prepared materials have better adsorption capacity for sodium arsenite under acidic conditions of pH at 2.8–4; and the maximum adsorption capacity could reach about 70mg/g when the concentration was 300mg/L at 30°C. The pseudo-first-order and pseudo-second-order kinetic models were all in good agreement with the experimental data, further identifying the adsorption kinetics mechanism of FSC on arsenic. Because NZVI alone is easily oxidized in the air, and agglomeration is also likely to occur, the combination of NZVI, silica and cotton fiber perfectly solved these defects and further improved the adsorption performance in this work. Moreover, the comparison on removal effects of various adsorbents simultaneously indicates that FSC will have a great application prospect in the future water pollution treatment.