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.

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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.