ZnO-TiO2 doped polyacrylonitrile nano fiber-Mat for elimination of Cr (VI) from polluted water

Abstract

PAN nanofiber-Mat (n-fib@Mat), PAN/ZnO n-fib@Mat, and PAN/ZnO-TiO2 n-fib@Mat were prepared via electrospinning method. Their high adsorption capacities against dissolved Cr (VI) ions make them as super adsorbents for water treatment. The structure of n-fib@Mat was investigated using XRD, FTIR, SEM, and TEM techniques. The effects of selected parameters such as contact time, initial concentration, and n-fib@Mat amount were assessed in a fixed bed reactor. It was found that the adsorption capacities of PAN n-fib@Mat, PAN/ZnO n-fib@Mat, and PAN/ZnO-TiO2 n-fib@Mat were pH-dependent and the optimal pH value was between 2.1 and 2.2. The adsorption was rapid, and the equilibrium was reached within 240 min to remove of Cr (VI) ions for PAN/ZnO-TiO2 n-fib@Mat and 360 min for PAN n-fib@Mat and PAN-ZnO n-fib@Mat. Langmuir isotherms model is preferred for PAN n-fib@Mat, PAN-ZnO n-fib@Mat, and PAN/ZnO-TiO2 n-fib@Mat for Cr (VI) adsorption. The equilibrium adsorption capacities are 153.85 mg/g, 234.52 mg/g, and 333.43 mg/g for PAN n-fib@Mat, PAN/ZnO n-fib@Mat, and PAN/ZnO-TiO2 n-fib@Mat for Cr (VI), respectively. The produced n-fib@Mat showed excellent removal ability for Cr (VI). The adsorption kinetic was obeyed pseudo-second-order reaction rate.