Adsorptive removal of arsenic from aqueous solution by zeolitic imidazolate framework-8 (ZIF-8) nanoparticles

•ZIF-8 nanoparticles have been fabricated via a facile method at room temperature.•The ZIF-8 nanoparticles show high adsorption capacity for arsenic removal at neutral and basic conditions.•Electrostatic attraction and hydroxyl and amine groups play key roles in the adsorption process. In this study, zeolitic imidazolate framework-8 (ZIF-8) nanosorbent was successfully synthesized via a facile method at room temperature. The ZIF-8 nanoparticles were characterized by nitrogen sorption, powder X-ray diffraction, field emission scanning electron microscope, transmission electron microscopy and Zeta potential. The synthesized ZIF-8 nanoparticles exhibited a high surface area of 1063.5m2/g and were of 200–400nm in particle size. The kinetic and isotherm data of arsenic adsorption on ZIF-8 were well fitted by pseudo-second-order and Langmuir models, respectively. The maximal adsorption capacities of As(III) and As(V) were of 49.49 and 60.03mg/g, respectively, at T=25°C and pH 7.0. The ZIP-8 nanoparticles were stable at neutral and basic conditions. However, large amounts of Zn2+ were released into water from the sorbent at acidic condition, which dramatically hindered the adsorption of arsenic. SO42− and NO3− had no significant effect on the arsenic adsorption while the adsorption was significantly inhibited by PO43− and CO32−. X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy analysis revealed that electrostatic attraction and hydroxyl and amine groups on ZIF-8 surface played vital roles in the adsorption process.