• 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.

Waste agricultural biomass available abundantly with limited utilization. The cocoa pod husks comprise of inorganic compounds particularly potassium oxide which can be used as a catalyst for biodiesel production. The waste cocoa pod husks were successfully transformed into a heterogeneous catalyst under calcination at 750 °C for 4 hours. The calcined cocoa pod (CCP) was characterized using thermogravimetric analysis (TGA), x-ray diffraction (XRD), x-ray fluorescence (XRF), and scanning electron microscope – energy dispersive x-ray (SEM EDX) while the catalytic activity was evaluated using parameters of reaction time, catalyst weight, molar ratio of palm oil to methanol and rotational speed of a homogenizer. The biodiesel conversion of 96.2 ± 0.3 % was achieved under reaction conditions of a reaction time of 20 minutes, and a catalyst weight of 7 wt% (based on oil weight), molar ratio of 1:15 and rotational speed of 6000 rpm. The homogenizer-intensified biodiesel production using waste CCP as a heterogeneous catalyst could save reaction time by 87–65 % compared with other studies.

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.

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.

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

The efficacy of waste chicken eggshells as a heterogeneous catalyst is investigated for biodiesel production from high-free fatty acid feedstock under microwave irradiation. The calcined waste chicken eggshells were identified using Thermogravimetric Analysis (TGA), X-ray Diffraction (XRD), X-ray Fluorescence (XRF) and Scanning Electron Microscope (SEM) equipped with Energy Dispersive X-ray (EDX). The effect of esterification conditions such as catalyst weight, molar ratio of oleic acid to methanol, reaction time and microwave power were determined on biodiesel conversion and yield. The highest conversion and yield of 92.04 ± 0.8 % and 78.75 ± 1.8 %, respectively, were achieved under the reaction condition of molar ratio of 1:15, catalyst weight of 6 wt%, reaction time of 20 minutes and microwave power of 60 %. The catalytic stability of calcined waste chicken eggshells revealed that the weight of CaO was decreased after the first cycle. However, the biodiesel conversion was above 80 % after five times usage.

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