Ugwele F O, Aninwede C S, Chime T O, Christian O Asadu, Innocent S Ike
Department of Chemical Engineering, Enugu State University of Science and Technology, Nigeria.
Department of Chemical Engineering, Gregory University, Uturu, P.M.B 1012, Abia State, Nigeria.
Heliyon. 2020 Oct 7;6(10):e05062. doi: 10.1016/j.heliyon.2020.e05062. eCollection 2020 Oct.
Optimization of process parameters for the regeneration of used mobil oil by acid/clay method using sulphuric acid as washing agent was successfully carried out. Used mobil oil was characterized before and after regeneration to determine the changes in the physicochemical properties of the oils. The viscosity, flash point and fire point of the oil increased after regeneration while the specific gravity and sulphur content decreased. The Atomic Absorption Spectrometry (AAS) carried out revealed the presence of eight different metals in the fresh mobil whose concentration increased during use but reduced after regeneration. The FTIR instrumentation analysis revealed that the used mobil oil has high concentration of some ester groups, aromatic materials, glycol and sulphur oxidation products while the proportion of these materials plunged significantly after treatment. Changes in the process conditions like acid concentration, settling time and bleaching temperature affected the effectiveness of the regeneration process by affecting the desired changes in the physicochemical properties. The process parameters were optimized using Central Composite Rotatable Design (CCRD) of Response Surface Methodology (RSM), with the aid of design expert. The design, which use purity as the response of the experiment, considered three independent factors of acid concentration, settling time and bleaching temperature; and the effects of these factors on the response are significant since their P-values are less than 0.05. An optimum theoretical purity of 0.86 was obtained at 6.5mol/lit acid concentration, 5.5hours settling time and 95.5 °C bleaching temperature, which agreed excellently with 0.85 actual purity obtained at the same conditions. Therefore, the regenerated mobil oil at these optimal conditions is capable of meeting commercial expectations.
以硫酸为洗涤剂，采用酸/白土法对废旧美孚机油进行再生处理，成功实现了工艺参数的优化。对废旧美孚机油再生前后进行了表征，以确定机油理化性质的变化。再生后，机油的粘度、闪点和燃点升高，而比重和硫含量降低。原子吸收光谱法（AAS）分析表明，新鲜美孚机油中存在八种不同的金属，其浓度在使用过程中增加，但再生后降低。傅里叶变换红外光谱仪（FTIR）分析表明，废旧美孚机油中某些酯基、芳烃、二醇和硫氧化产物的浓度较高，而处理后这些物质的比例显著下降。酸浓度、沉降时间和漂白温度等工艺条件的变化通过影响理化性质的预期变化，影响了再生过程的效果。借助设计专家软件，采用响应面法（RSM）的中心复合旋转设计（CCRD）对工艺参数进行了优化。该设计以纯度作为实验响应值，考虑了酸浓度、沉降时间和漂白温度三个独立因素；这些因素对响应值的影响显著，因为它们的P值小于0.05。在酸浓度为6.5mol/L（摩尔每升）、沉降时间为5.5小时、漂白温度为95.5℃的条件下，获得了0.86的最佳理论纯度，这与在相同条件下获得的0.85实际纯度非常吻合。因此，在这些最佳条件下再生的美孚机油能够满足商业预期。
