In this study, wastewater was utilized as an inexpensive medium for cultivating microalgae for biodiesel production using SO₄²⁻/Fe₃O₄-Al₂O₃ as a magnetic nanocatalyst. Next, some parameters affecting the growth of microalgae in a non-sterile medium (municipal wastewater), catalyst activity (sulfate and ferric oxide concentrations), and biodiesel production (transesterification reaction conditions) were assessed. Regarding the weight of cultivated microalgae, the highest growth was obtained after 5 days. The results of the catalyst studies indicated the important role of the sulfate groups in the activity of the alumina with the highest activity obtained at 2 M concentration of sulfuric acid. These groups formed sulfated alumina structures as active phases causing enhanced surface area, acidity, and activity. Further, the addition of ferric oxide to alumina at Fe/Al ratio of 0.25 resulted in production of a catalyst with suitable activity and magnetic properties while the sample with Fe/Al ratio of 0.15 and 0.35 presented negligible magnetic properties and insufficient enhancement in the activity, respectively. Finally, a yield of 87.6% was obtained using the best magnetic nanoparticle under the optimum conditions of 120 °C, catalyst concentration of 8 wt%, 9 mL methanol/g microalgae, and 4 h of reaction time. The best sample also showed appropriate reusability such that its activity declined by around 14.2% after the fifth cycle of use.

在这项研究中，废水被用作廉价的培养基，以使用SO ₄ ^2- / Fe ₃ O ₄ -Al ₂ O ₃培养用于生产生物柴油的微藻。作为磁性纳米催化剂。接下来，评估了影响非无菌介质（市政废水）中微藻生长，催化剂活性（硫酸盐和三氧化二铁浓度）和生物柴油产量（酯交换反应条件）的一些参数。关于培养的微藻的重量，在5天后获得最高的生长。催化剂研究的结果表明，硫酸根基团在氧化铝的活性中具有重要作用，在2M的硫酸浓度下，该活性最高。这些基团形成硫酸化的氧化铝结构作为活性相，导致表面积，酸度和活性增强。此外，以0的Fe / Al比向氧化铝中添加氧化铁。图25的结果产生了具有合适的活性和磁性的催化剂，而Fe / Al比为0.15和0.35的样品分别具有可忽略的磁性和不足的活性增强。最后，使用最佳磁性纳米颗粒，在最佳条件下（120℃），催化剂浓度为8 wt％，9 mL甲醇/ g微藻类和4 h反应时间，获得了87.6％的收率。最好的样品还显示出适当的可重复使用性，因此在第五个使用周期后其活性下降了约14.2％。9毫升甲醇/克微藻类，反应时间为4小时。最好的样品还显示出适当的可重复使用性，因此在第五个使用周期后其活性下降了约14.2％。9毫升甲醇/克微藻类，反应时间为4小时。最好的样品还显示出适当的可重复使用性，因此在第五个使用周期后其活性下降了约14.2％。