Facile hydrothermally synthesized nanofibrous polyresorcinol@γ-Fe2O3 for dispersive ferrofluid adsorption of Cd(II): Modeling and isotherm study

Abstract

A novel ferrofluid mediated dispersive adsorption system was developed based on a facile hydrothermally synthesized nanofibrous polyresorcinol@γ-Fe2O3. The nanocomposite was characterized with energy dispersive X-ray spectroscopy, X-ray diffraction, field emission scanning electron microscopy, vibrating sample magnetometer, Brunauer–Emmett–Teller and Fourier transform infrared techniques. Polysorbate and a new synthetic Schiff base were used as carrier fluid and complexing agent, respectively. To obtain effective parameters (pH, amount of sorbent and ligand and contact time) on adsorption and their interactions, response surface methodology with Box–Behnken design was used. Results confirmed that adsorption efficiency was very sensitive to pH, adsorbent dosage and amount of ligand; however, the efficiency is less sensitive to time. Under optimized conditions (pH 8; contact time 3.8 min; sorbent amount 300 μL and amount of ligand 1.3 × 10–5 mol) relative standard deviation (%) and the limit of detection was 4% and 0.13 μg L–1, respectively. Reusability of the sorbent was achieved with 0.1 mol L–1 of HNO3 solution. Isotherm study revealed that cadmium adsorption followed Langmuir model with maximum capacity of 56.4 mg g–1. Moreover, results for Dubinin–Radushkevich and Temkin isotherm models confirmed that cadmium adsorption is a physical process. Finally developed method was used for cadmium preconcentration from water and food samples with satisfactory results.