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.

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.

Co-valorization of agro-industry by-products: effect of citrus oil on the quality of soap derived from palm fatty acid distillate and spent bleaching clay

This study deals with the co-valorization of spent bleaching clay (SBC) and palm fatty acid distillate (PFAD) –by-products of palm oil refining plants- through soap manufacture. Obtained SBC and PFAD samples show differing acidity and saponification values depending on fatty acids and acylglycerols content. Soaps are prepared using the stoichiometric amount of NaOH, under the varying proportion of water introduced through the basic solution. The mixing SBC and PFAD (ratio 1:3), the reaction completion (92.5%) is surprisingly higher than expected, indicating a synergistic effect on the course of the saponification reaction. The water is also a critical parameter, 30% w/w of added water allowing the highest yield. When testing for cleaning efficiency the products having the highest soap content, those from individual by-products give a low microbial count reduction after hand-washing (30-37%). But a much better score (74%) is obtained when using SBC:PFAD soap mixtures. This improvement could be due to abrasive and absorption effects of the clay, combined with the high soap content. The acceptability through a panel test is good for all soaps when formulated with citrus oil. The most active product corresponds to a SBC:PFAD ratio close to the production one in refining plants. Therefore these results provide an easy way for co-valorising these by-products, after further optimizing the saponification reaction in this complex triphasic medium (aqueous solution, oil, clay).