• Energy Research

Biodiesel production from waste cooking oil is a viable alternative both to satisfy renewable energy demand and utilize a low-cost feedstock. However, a preparatory procedure is required to reduce free fatty acid contained in waste cooking oil to a specific value which is time- and energy-extensive. Herein, a fast and non-catalytic amidation reaction performs at room temperature is established as an alternative method to reduce the free fatty acid level. The effect of the molar ratio of waste cooking oil to monoethanolamine, reaction time and rotational speed of homogenizer were investigated on the conversion of free fatty acid to alkanolamide compounds. The highest conversion of 95.9 ± 0.02% was achieved in presence of a molar ratio of 1:1.5, reaction time of 0.5 min and rotational speed of 5000 rpm. Further, a homogenizer was used to facilitate the transesterification reaction using an alkaline catalyst at room temperature. The conversion of waste cooking oil to biodiesel of 91.4 ± 0.2% was achieved after 5 min of reaction time. In terms of processing parameters, the non-catalytic amidation and alkaline base catalytic transesterification reaction assisted by a homogenizer device is a time-saved process as it could save 92% and 94% of reaction time compared to one- and two-steps method and was performed in ambient condition.

A low-cost, green, and highly active catalyst which could transesterify oil under ambient conditions is required to reduce the biodiesel production cost. A novel heterogeneous catalyst derived from the waste agroproduct has been developed from passion fruit peel. The catalytic activity of calcined waste passion fruit peel (WPFP) which mainly contains potassium in the form of chloride and carbonate has been evaluated using factorial design to determine the interaction of molar ratio of oil to methanol, catalyst weight, and reaction time with three different reaction conditions such as 65, 45 °C, and room temperature. The transesterification of palm oil to biodiesel achieved a conversion of >90% for all variables determined at a reaction temperature of 45 and 65 °C, respectively, while a maximum biodiesel conversion of 95.4 ± 2.8% was obtained at room temperature and a reaction time of 30 min. The addition of certain amounts of the catalyst is required to reuse the catalyst as the leaching study showed the reduction of 22% of catalyst weight. The ability of calcined WPFP to catalyze transesterification at room temperature opens up the possibility to reduce biodiesel production cost.

Insect larvae contain sufficient oil comparable with oleaginous biomass, and hence have potency as alternative biodiesel resources. The direct transesterification of Black Soldier Fly (BSF) larvae have conducted using a controllable crushing device (CCD) and a homogeneous base as a catalyst. The effect of catalyst concentration (wt.%), ratio BSF larvae to methanol (wt./v), reaction time (min) and rotational speed (rpm) on biodiesel conversion was determined. The maximum conversion of 93.8% was achieved at room temperature after 20 min of reaction time and ratio larvae to methanol of 1:2 (wt./v), catalyst concentration of 7 wt% and rotational speed of 3000 rpm. In addition, the green metrics calculation showed that this method produces less waste and uses less solvent. Some of the BSF-biodiesel properties meet the biodiesel standard. The CCD-intensified the DT of BSF larvae is a promising alternative for green and energy-saved biodiesel production.

A bottleneck in the production of biodiesel from microalgae is the dewatering and lipid extraction process which is the dominant energy penalty and cost. A novel biodiesel production platform based on vortex fluidic device (VFD)-assisted direct transesterification (DT) of wet microalgal biomass of Chloroparva pannonica was developed and evaluated. Fatty acid extraction and fatty acid to FAME conversion efficiencies were used at different parameter settings to evaluate performance of the processing technology in confined and continuous mode. A response surface method based on Box-Behnken experimental design was used to determine the effects of water content, the ratio of biomass to methanol and residence time in the VFD. Average extraction efficiencies were 41% and conversion efficiencies >90% with the processing technology showing a broad tolerance to parameter settings. The findings suggest that VFD-assisted DT is a simple and effective way to produce biodiesel directly from wet microalgae biomass at room temperature.

Here, we demonstrate the direct biodiesel production from wet SCG in mild reaction temperature and short reaction time using reactive extraction Soxhlet (RES) method.

A multistep and high-cost biodiesel production could be simplified using the direct transesterification (DT) method.

Direct biodiesel production from wet fungal biomass may significantly reduce production costs, but there is a lack of fast and cost-effective processing technology. A novel thin film continuous flow process has been applied to study the effects of its operational parameters on fatty acid (FA) extraction and FA to fatty acid methyl ester (FAME) conversion efficiencies. Single factor experiments evaluated the effects of catalyst concentration and water content of biomass, while factorial experimental designs determined the interactions between catalyst concentration and biomass to methanol ratio, flow rate, and rotational speed. Direct transesterification (DT) of wet Mucor plumbeus biomass at ambient temperature and pressure achieved a FA to FAME conversion efficiency of >90% using 3 wt/v % NaOH concentration, if the water content was ≤50% (w/w). In comparison to existing DT methods, this continuous flow processing technology has an estimated 90-94% reduction in energy consumption, showing promise for up-scaling.

Waste bio-based materials generated as by-products of palm oil mills have been successfully used as a heterogeneous catalyst in homogenizer-intensified biodiesel production. Palm bunch ash (PBA) contains potassium oxide as a major component that could catalyze palm oil to biodiesel at room temperature. The influential transesterification conditions such as ratio molar palm oil to methanol, rotational speed, catalyst weight and reaction time were investigated on biodiesel conversion. The highest conversion of 98.9% was obtained in presence of a ratio molar of 1:15, rotational speed of 4000 rpm, catalyst weight of 18 wt.% and 10 min reaction times. The catalytic stability test revealed that both catalyst amount and K2O concentration decreased after one reaction cycle. However, no calcination is required and the availability of PBA is abundantly in palm oil producer countries increasing its competitiveness to use as a heterogeneous catalyst. In addition, this process could save 6–98% of electricity consumption and 67–87% of reaction time compared to other methods.