Fibrous deep-bed filtration for oil/water separation using sunflower pith as filter media

The application of agricultural by-products as filter bed material for the treatment of oily wastewater is preferable due to their biodegradability and availability. The goal of this paper was to examine the sorption and filtration properties of sunflower (Lat. Helianthus annuus) fibres in a raw state. SEM imaging and nitrogen adsorption at −196.15 °C were applied to evaluate sorbent morphology. FTIR spectroscopy was used to determine the chemical composition of the pith. Studies on sorption in static conditions (pith fragmentation 1.5–4.0 mm) allowed process kinetics to be specified. The experimental kinetics was fitted to pseudo first-order and pseudo second-order kinetics by a non-linear method. To better predict kinetic parameters, a new modified logistic equation was proposed. Sunflower fibre was found to have high oil sorption capacity (12.67 g/g) and good retention properties. During filtration experiments, an artificial reservoir brine (0.1, 2.0, and 20.0 g/l of oil) was used as an oil-in-water emulsion; sunflower pith was used as a filter medium. The influence of four process parameters (pH, bed height, initial oil concentration, and flow rate) on removal efficiency was studied. Oil concentrations were determined by gas chromatography. The results demonstrated that the prepared filters operated better at a lower pH, lower flow, a deeper bed material, and higher concentration of inlet oil. The filtration efficiency for the removal of crude oil from oily brines reached more than 99% in the initial stage of the process. The results obtained suggest that natural plant fibres can be an effective bed material to separate oil from oily brine.