A novel bleaching approach: Microwave assisted sunflower oil bleaching and optimization

The factors affecting the microwave bleaching of sunflower oil and the interaction between them were investigated and optimized by response surface methodology using a three-factor five-level central composite rotatable design. Microwave power, time and the amount of bleaching clay were selected as independent variables studied in the range of 70-120 W, 2-15 min, and 0.01-0.5%. The dependent variables that measure the bleaching efficiency and oil quality were evaluated as hue angle, chroma and totox value. Optimization was carried out by minimizing totox and chroma and maximizing hue angle. Hue angle, chroma and totox were found as 96.91, 37.66 and 23.31 under optimal conditions. Optimal microwave bleaching was successfully performed by using less bleaching clay (0.4%) and a shorter time (8 min) compared to the current industrial application without any adverse effect on oil quality. Hence, microwave bleaching is thought to be an alternative method for the bleaching of edible oils.

Adsorption of Yttrium Ions on 3-Amino-5-Hydroxypyrazole Impregnated Bleaching Clay, a Novel Sorbent Material

In this work, spent bleaching clay (SBC) was treated with ethyl acetate and impregnation with 3-amino-5-hydroxypyrazole (AHIBC) that utilized as economical sorbent material. The uptake of yttrium ions from aqueous solution using AHIBC was studied under batch process as a function of pH of the solution, contact time, adsorbent dosage, Yttrium ions concentration, and ambient temperature. The adsorption equilibrium was achieved at the value of pH = 6.0 and agitation time of 60 min at room temperature. The utmost adsorption capacity of Y(III) ions on AHIBC was 171.32 mg·g−1. Kinetic, isotherm, and thermodynamic models were applied to the experimental data obtained. Adsorption follows a pseudo–second–order kinetic model, while the adsorption isotherm fits the Langmuir model. A negative value of Gibbs free energy ΔG° revealed that the adsorption of the Y ions on the AHIBC adsorbent was spontaneously in nature. In addition, the electrostatic interaction process between the metal ions and AHIBC was favorable. The negative value of ΔH° states that Y ions adsorption was an exothermic process. Desorption efficiency reduced from 97% to 80% after eight consecutive rounds.

Study of the Antioxidant Power of the Waste Oil from Palm Oil Bleaching Clay

Palm oil is one of the most consumed oils, one of whose refining steps is the removal of pigments and other substances using bleaching clay as adsorbent. Worldwide production of this oil was 70 million tons in 2017, requiring 1 t of clay to produce 1000 t of refined oil. The residual bleaching clay, having an oil fraction (12.70%) rich in phenolics, carotenoids and tocopherols, was extracted in this study with ethanol to obtain an antioxidant-rich palm oil bleaching extract (POBE), with the aim of using it as a natural antioxidant source. The POBE antioxidant capacity determined by the DPPH method corresponded to a 20.29% inhibition of radical formation. The POBE was also tested for its potential to enhance oxidative stability of passion fruit, pracaxi and Brazil nut oils used as reference oils, and compared to common synthetic antioxidants (tert-butylhydroquinone and propyl gallate), either separately as controls or in mixtures with them. Besides the increased oxidative stability of these oils induced by the POBE, a positive synergistic effect between it and the synthetic antioxidants was observed. These results taken together suggest that the exploitation of the waste oil from bleaching clay as an additive to improve the oxidative stability of biofuels or lubricating oils is feasible.

Regeneration of spent bleaching clay by ultrasonic irradiation and its application in methylene blue adsorption

An effective method that combines solvent extraction with ultrasonic irradiation was developed to recycle spent bleaching clay (SBC) from modern oil refinery plants. The principle of ‘waste to treasure’ was used to achieve the regenerated SBC. Various characterization techniques were applied to analyse and compare regenerated SBC and commercial bleaching clay (CBC). The structure of the regenerated SBC did not show any obvious change compared with that of CBC, but the Brunauer–Emmett–Teller-specific surface area (SBET) and pore-volume values of the regenerated SBC increased. At the same time, the parameters of the regenerated SBC reached national standards. In addition, the samples were used as low-cost adsorbents for the adsorption of methylene blue (MB) from water. The regenerated SBC had greater adsorption efficiency and cycle performance for MB than CBC. Hence, the SBC may be treated by ultrasonic radiation combined with extraction, and the regenerated SBC has better properties than CBC. This work opens up a new approach to the regeneration and utilization of SBC and raises the potential of ultrasonic irradiation as an environmentally friendly method to be applied to various regeneration systems.