Fossil fuels’ pollution and their non-renewability have motivated the search for alternative fuels. Some common example of seed oils are sunflower oil, date seed oil, soy bean oil. For instance, soy methyl and soy-based biodiesel are the main biodiesel. Biodiesel is a clean diesel fuel that can be produced through transesterification reaction. Recycled cooking oil, on the other hand, is one of the inexpensive, easily available sources for producing biodiesel. This article is aimed at production of biodiesel via trans-esterification method, Nano CaO synthesis using sol-gel method, and Nano MgO synthesis using sol-gel self-combustion. Two catalysts’ combination affecting the reaction’s efficacy was also discussed. Optimum conditions for the reaction in the presence of Nano CaO are 1.5 % weight fracture, 1:7 alcohol to oil proportion and 6 h in which biodiesel and glycerin (the byproduct) are produced. Moreover, the optimum conditions for this reaction in the presence of Nano CaO and Nano MgO mixture are 3 % weight fracture (0.7 g of Nano CaO and 0.5 g of Nano MgO), 1:7 alcohols to oil proportion and 6 h. Nano MgO is not capable of catalyzing the transesterification by itself, because it has a much weaker basic affinity but when used with Nano CaO due to its surface structure, the basic properties increase and it becomes a proper base for the catalyst so that CaO contact surface increases and transesterification reaction yield significantly increases as well. This study investigates the repeatability of transesterification reaction in the presence of these Nano catalysts as well.

In the present study, removal of metal ions Pb (II) using nanostructured γ-alumina was investigated in a fixed-bed column. Comparison of Thomas, Yoon-Nelson, and Adams-Bohart models with experimental kinetic results was done, and model parameters were evaluated by linear regression analysis for Pb ²⁺ adsorption in different bed heights, initial concentrations, and flow rates. The obtained experimental data are in good agreement with Thomas and Yoon-Nelson models, but in the case of Adams-Bohart model, low correlation coefficient is observed.

Impact of dust concentration and weather conditions – wind speed and relative humidity – on power generation of photovoltaic (PV) panels investigated experimentally in Tehran, Iran, for the period of April 10–September 22, 2018. Two Photovoltaic panels together with data-logging equipment were applied in this experiment. One panel was cleaned every day, while the other was remained unclean after 45 days. A performance ratio called “cleanness index” (CI) which is a temperature-corrected performance ratio of a soiled PV panel to that of a clean one was also used to indicate the dust deposition effect on PV panel performance. The uncertainty range of experimental results was between 5.27% and 5.55%. The results show that cleanness index had positive correlation with wind speed and negative correlations with relative humidity and dust concentration. Thus, in comparison to the clean PV panel, the output-power of the soiled panel reduced, approximately 8–12% per month. Furthermore, in order to numerically predict daily change of cleanness index (ΔCI_Pre), a linear regression model was developed and the outcome revealed that dust concentration had the most impact, with 21.56%.