Summary Torrefied biomass is a commercial fuel, which is particularly produced from woody biomass via torrefaction and alternative to coal to reduce greenhouse gas emissions in the short term. In this study, torrefaction conditions of cotton stalk were optimised, and the effect of bulk density together with temperature and residence time on process yields and characterisation of torrefied cotton stalk was investigated. Response surface methodology using Box‐Behnken design was employed for the design of experiments and optimization. Cotton stalk was torrefied at a temperature between 260°C and 320°C, in 10, 35, and 60 minutes with bulk density of 125, 150, and 175 kgm−3. Temperature was the most effective parameter for the six responses (higher heating value, carbon content, hydrogen/carbon and oxygen/carbon ratios, mass loss, and energy yield). Besides, temperature/bulk density interaction was found to be significant for all responses whereas residence time/bulk density interaction was effective for process yields. The optimization results showed that more economical torrefied biomass with similar quality of lignite could also be produced under process conditions of 305°C‐32 minutes‐158 kgm−3. At this point, higher heating value and carbon content of product were calculated as 19.7 MJ kg−1 and 64%, respectively.

In this study, an innovative approach was carried out using the geographic information systems (GIS)-based multi-criteria evaluation model to assign the use priority in agricultural lands needing to be improved for management and sustainability of biochar application in the soil. The model included (1) site suitability assessments, (2) standardization of assessment factors, and (3) equal-weighted overlay. By this model, the first map of primary biochar application areas for Turkey was prepared. As a result, the suitability scores were divided into five classes in the range of 0.20-0.90, and thus, the areas were found mostly in the moderate suitability (between 0.49 and 0.64). Consequently, it was determined that the biochar application was very highly suitable in the Aegean and Marmara regions. While the western and central parts of the Mediterranean region had high suitability, Central Anatolia and Southeastern Anatolia regions had very low suitability. The study results also indicated that the requirement for biochar addition was very low in the arable agricultural areas such as Harran in the Southeastern Anatolia region, Çukurova in the Mediterranean region, and Konya and Amasya in the Central Anatolia region. However, there is a need for showing particular attention to the agricultural areas of the Aegean Region, Ergene in the Marmara Region, and Iğdır in the Eastern Anatolian region due to higher biochar need for intensive agriculture.

Currently, monoglycerides (MG) are produced using a complicated energy-intensive technology that contributes negatively toward greenhouse gas mitigation. This work suggests a cleaner and simpler one-step enzymatic production of α-monolaurin in an inert membrane reactor, where the reaction and enzyme separation are conducted simultaneously in one unit. Candida antarctica lipase (Lipozyme 435) was used to catalyze the esterification reaction between lauric acid and glycerin in a solvent-free system under mild temperatures. Response surface methodology was used to optimize the reaction conditions. The optimal conditions were a molecular sieve of 14.85% w/w, a temperature of 56.95 °C, an enzyme amount of 5.38% w/w, and a molar ratio of 4.75% w/w. The gas chromatography (GC) analysis showed that the α-monolaurin percentage was 49.5% when the enzymatic process (ENZ) was used. The conventional chemical (CHEM) and autocatalytic (AUT) esterification methods were also performed to study their proportional MG yields. The GC results showed the MG percentages of 43.9 and 41.7% for CHEM and AUT, respectively. Economic analysis was also conducted for the suggested enzymatic technique, and the findings were compared with those of the CHEM and AUT technologies. Using a plant capacity of 4950 t/year and 11% interest for the proposed ENZ process, the total capital investment of α-monolaurin production was preferably four times less than that of the CHEM process and three times less than that of the AUT method, presenting investment possibilities. However, the ENZ process showed the least profitability (net profit per day) among the three processes. Nevertheless, the return on investment and net present value for the ENZ process were preferably higher than those of CHEM and AUT because of its interestingly lower inside battery limit plant cost and less energy consumption. The AUT/CHEM processes generated a total carbon dioxide (CO2) exhaust of 678.7 t CO2 eq./year. In contrast, the ENZ process exhausted a total CO2 of only 50 t CO2 eq./year. The present integrated techno-economic and environmental study of α-monolaurin production emphasizes the green and cost benefits of the proposed ENZ technology. Graphical Abstract

Currently, monoglycerides (MG) are produced using a complicated energy intensive technology that contributes negatively toward greenhouse gas mitigation. This work suggests a cleaner and simpler one-step enzymatic production of α-monolaurin in an inert membrane reactor, where the reaction and enzyme separation are conducted simultaneously in one unit. Candida antarctica lipase (Lipozyme 435) was used to catalyze the esterification reaction between lauric acid and glycerin in a solvent-free system under mild temperatures. Response surface methodology was used to optimize the reaction conditions. The optimal conditions were a molecular sieve of 14.85% w/w, a temperature of 56.95°C, an enzyme amount of 5.38% w/w, and a molar ratio of 4.75% w/w. The gas chromatography (GC) analysis showed that the α-monolaurin percentage was 49.5% when the enzymatic process (ENZ) was used. The conventional chemical (CHEM) and autocatalytic (AUT) esterification methods were also performed to study their proportional MG yields. The GC results showed the MG percentages of 43.9% and 41.7% for CHEM and AUT, respectively. Economic analysis was also conducted for the suggested enzymatic technique, and the findings were compared with those of the CHEM and AUT technologies. Using a plant capacity of 4950 t/year and 11% interest for the proposed ENZ process, the total capital investment of α-monolaurin production was preferably four times less than that of the CHEM process and three times less than that of the AUT method, presenting investment possibilities. However, the ENZ process showed the least profitability (net profit per day) among the three processes. Nevertheless, the return on investment and net present value for the ENZ process were preferably higher than those of CHEM and AUT because of its interestingly lower inside battery limit plant cost and less energy consumption. The AUT/CHEM processes generated a total carbon dioxide (CO2) exhaust of t CO2 678.7 eq./year. In contrast, the ENZ process exhausted a total CO2 of only 50 t CO2 eq./year. The present integrated techno-economic and environmental study of α-monolaurin production emphasizes the green and cost benefits of the proposed ENZ technology.

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