The industrial application of lactic acid is very broad; hence, the high demand is forecasted to multiply in the future. This review presented the major problems for the efficient production of lactic acid from lignocellulose biomass using lactic acid bacteria (LAB) and further proposes three promising solutions to solve these problems, exposing their potentials and future research needs. Recombinant cellulolytic strategy in LAB promises a significant reduction of lactic acid production costs, however, extensive research on genetic engineering is still needed. Microwave‐assisted deep eutectic solvent pretreatment is extremely fast and produces little to no harmful by‐products, but it has not been investigated for lactic acid production yet. Continuous simultaneous saccharification and fermentation with enzyme and cell recycle is newly proposed by the authors as a process set up that can solve the problems of feedback‐, substrate‐ and end‐product inhibition while resulting in higher lactic acid productivities, yield, and concentration.

Biodiesel is a sustainable and renewable source of fuel. It has been considered as a comparable substitute to petro‐diesel, which is a fast depleting resource. Many studies have been undertaken on biodiesel production from various feedstock as a result of its importance. The differences between the physico‐chemical properties of biodiesel and petro‐diesel were considered with the aim of justifying the applicability of biodiesel in compression ignition engines (CIE). It was established that biodiesel has relatively close BTE (brake thermal efficiency) and BSFC (brake specific fuel consumption) values with petro‐diesel, hence, is suitable for CIE operation without any modification. The exhaust from CIE using biodiesel was lower compared to petro‐diesel and this confirms the environmental friendliness of biodiesel. The catalyst being an important substance in the transesterification reaction of vegetable oil/animal fat to produce biodiesel was comprehensively discussed, and heterogeneous catalysts were established to be preferred due to several advantages over homogenous catalysts. This paper reviews biodiesel production, prospects, benefits and challenges as a replacement for petrol diesel.

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Waste-iron-filling (WIF) served as a precursor to synthesize α- through the co-precipitation process. The α- was converted to solid acid catalysts of RBC500, RBC700, and RBC900 by calcination with temperatures of 500, 700 and 900 °C respectively and afterwards sulfonated. Among the various techniques employed to characterize the catalysts is Fourier transforms infrared spectrometer (FT-IR), X-ray diffraction (XRD and Scanning electron microscopy (SEM). Performance of the catalysts was also investigated for biodiesel production using waste cooking oil (WCO) of 6.1% free fatty acid. The XRD reveals that each of the catalysts composed of Al– . While the FT-IR confirmed acid loading by the presence of groups. The RBC500, RBC700, and RBC900 possessed suitable morphology with an average particle size of 259.6, 169.5 and 95.62 nm respectively. The RBC500, RBC700, and RBC900 achieved biodiesel yield of 87, 90 and 92% respectively, at the process conditions of 3 h reaction time, 12:1 MeOH: WCO molar ratio, 6 wt% catalyst loading and 80 °C temperature. The catalysts showed the effectiveness and relative stability for WCO trans-esterification over 3 cycles. The novelty, therefore, is the synthesis of nano-solid acid catalyst from WIF, which is cheaper and could serve as an alternative source for the ferric compound.

Sugarcane (Saccharum officinarum) bagasse (SCB) is a biomass of agricultural waste obtained from sugarcane processing that has been found in abundance globally. Due to its abundance in nature, researchers have been harnessing this biomass for numerous applications such as in energy and environmental sustainability. However, before it could be optimally utilised, it has to be pre-treated using available methods. Different pre-treatment methods were reviewed for SCB, both alkaline and alkali–acid process reveal efficient and successful approaches for obtaining higher glucose production from hydrolysis. Procedures for hydrolysis were evaluated, and results indicate that pre-treated SCB was susceptible to acid and enzymatic hydrolysis as > 80% glucose yield was obtained in both cases. The SCB could achieve a bio-ethanol (a biofuel) yield of > 0.2 g/g at optimal conditions and xylitol (a bio-product) yield at > 0.4 g/g in most cases. Thermochemical processing of SCB also gave excellent biofuel yields. The plethora of products obtained in this regard have been catalogued and elucidated extensively. As found in this study, the SCB could be used in diverse applications such as adsorbent, ion exchange resin, briquettes, ceramics, concrete, cement and polymer composites. Consequently, the SCB is a biomass with great potential to meet global energy demand and encourage environmental sustainability.

A solid catalyst for biodiesel production was synthesized from dolomite by calcination at different temperatures of 800 and 900 o C for 2 h. The catalyst was characterized by scanning electron microscopy (SEM) and Brunauer Emmett Teller (BET). Its performance in the production of palm kernel biodiesel (PKB) using palm kernel oil in an optimization study was carried out by a definitive screening design. The varying process parameters for the optimization were methanol:oil molar ratio, reaction temperature, catalyst quantity, reaction time and dolomite calcination temperature. Tendency and extent of the catalyst reusability were also studied. The catalysts were found to contain calcium and magnesium oxides with morphological structures of: surface areas 507 and 560 m 2 /g, pore volumes 0.180 and 0.199 cm 3 /g, and pore sizes 27.07 and 31.48 Ȃ for Dolomite Catalyst Calcined (DCC) at 800 o C (DCC800) and DCC at 900 o C (DCC900), respectively. The optimal parameters of methanol:oil molar ratio 12:1, temperature 65 o C, catalyst quantity 8% (w/w), time 4 h and DCC800 gave an optimum yield of 98.69% biodiesel. The catalyst was reused for the 8 th cycle after which the %yield of PKB decreased by <4%. It can be concluded that the dolomite catalyst has a great activity and potential as a viable catalyst for quality biodiesel production.

Shea butter (SB) was extracted from its kernel by using n-hexane as solvent in an optimization study. This was to determine the optima operating variables that would give optimum yield of SB and to study the effect of solvent on the physico-chemical properties and chemical composition of SB extracted using n-hexane. A Box-behnken response surface methodology (RSM) was used for the optimization study while statistical analysis using ANOVA was used to test the significance of the variables for the process. The variables considered for this study were: sample weight (g), solvent volume (ml) and extraction time (min). The physico-chemical properties of SB extracted were determined using standard methods and Fourier Transform Infrared Spectroscopy (FTIR) for the chemical composition. The results of RSM analysis showed that the three variables investigated have significant effect (p < 0.05) on the %yield of SB, with R(2) - 0.8989 which showed good fitness of a second-order model. Based on this model, optima operating variables for the extraction process were established as: sample weight of 30.04 g, solvent volume of 346.04 ml and extraction time of 40 min, which gave 66.90 % yield of SB. Furthermore, the result of the physico-chemical properties obtained for the shea butter extracted using traditional method (SBT) showed that it is a more suitable raw material for food, biodiesel production, cosmetics, medicinal and pharmaceutical purposes than shea butter extracted using solvent extraction method (SBS). Fourier Transform Infrared Spectroscopy (FTIR) results obtained for the two samples were similar to what was obtainable from other vegetable oil.

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