Biomass-derived porous aminated graphitic nanosheets for removal of the pharmaceutical metronidazole: Optimization of physicochemical features and exploration of process mechanisms
“…Conversion processes can be based on both biochemical or thermochemical routes. Generally, thermochemical processes are widely used for biomass conversion and energy recovery since they use well-developed technologies [1][2][3][4]. On the other side, biomass-derived carbohydrates represent a versatile platform for the production of a variety of final products [5].…”
Biomass-derived sugars are platform molecules that can be converted into a variety of final products. Non-food, lignocellulosic feedstocks, such as agroforest residues and low inputs, high yield crops, are attractive bioresources for the production of second-generation sugars. Biorefining schemes based on the use of versatile technologies that operate at mild conditions contribute to the sustainability of the bio-based products. The present work describes the conversion of giant reed (Arundo donax), a non-food crop, to ethanol and furfural (FA). A sulphuric-acid-catalyzed steam explosion was used for the biomass pretreatment and fractionation. A hybrid process was optimized for the hydrolysis and fermentation (HSSF) of C6 sugars at high gravity conditions consisting of a biomass pre-liquefaction followed by simultaneous saccharification and fermentation with a step-wise temperature program and multiple inoculations. Hemicellulose derived xylose was dehydrated to furfural on the solid acid catalyst in biphasic media irradiated by microwave energy. The results indicate that the optimized HSSF process produced ethanol titers in the range 43–51 g/L depending on the enzymatic dosage, about 13–21 g/L higher than unoptimized conditions. An optimal liquefaction time before saccharification and fermentation tests (SSF) was 10 h by using 34 filter paper unit (FPU)/g glucan of Cellic® CTec3. C5 streams yielded 33.5% FA of the theoretical value after 10 min of microwave heating at 157 °C and a catalyst concentration of 14 meq per g of xylose.
“…Conversion processes can be based on both biochemical or thermochemical routes. Generally, thermochemical processes are widely used for biomass conversion and energy recovery since they use well-developed technologies [1][2][3][4]. On the other side, biomass-derived carbohydrates represent a versatile platform for the production of a variety of final products [5].…”
Biomass-derived sugars are platform molecules that can be converted into a variety of final products. Non-food, lignocellulosic feedstocks, such as agroforest residues and low inputs, high yield crops, are attractive bioresources for the production of second-generation sugars. Biorefining schemes based on the use of versatile technologies that operate at mild conditions contribute to the sustainability of the bio-based products. The present work describes the conversion of giant reed (Arundo donax), a non-food crop, to ethanol and furfural (FA). A sulphuric-acid-catalyzed steam explosion was used for the biomass pretreatment and fractionation. A hybrid process was optimized for the hydrolysis and fermentation (HSSF) of C6 sugars at high gravity conditions consisting of a biomass pre-liquefaction followed by simultaneous saccharification and fermentation with a step-wise temperature program and multiple inoculations. Hemicellulose derived xylose was dehydrated to furfural on the solid acid catalyst in biphasic media irradiated by microwave energy. The results indicate that the optimized HSSF process produced ethanol titers in the range 43–51 g/L depending on the enzymatic dosage, about 13–21 g/L higher than unoptimized conditions. An optimal liquefaction time before saccharification and fermentation tests (SSF) was 10 h by using 34 filter paper unit (FPU)/g glucan of Cellic® CTec3. C5 streams yielded 33.5% FA of the theoretical value after 10 min of microwave heating at 157 °C and a catalyst concentration of 14 meq per g of xylose.
“…For MOF-5, all characteristic peaks at 2θ values of 6.85°, 9.69°, 13.74°, and 15.31° exist and match well to the standard pattern reported in the literature 44 . The XRD pattern for ACS-RGO shows a broad peak at 2θ values of 20 to 30° which belongs to the main index of graphite (2θ = 26°) with a space of about 3.34 Å between layers 45 , 46 . Figure 2 XRD patterns for as-synthesized MOF-5 and ACS-RGO.…”
Among cationic dyes, malachite green (MG) is commonly used for dying purposes and also as an inhibitor in aquaculture, food, health, and chemical industries due to its cytotoxic effects. Therefore, MG removal is essential to keep the ecosystem and human health safety. Adsorption is a viable and versatile option and exploring efficient adsorbents have high priority. Herein, MOF-5 and aminated corn Stover reduced graphene oxide (ACS-RGO) of typical adsorbents of metal–organic-frameworks (MOFs) and carbon-based classes were studied for MG removal. MOF-5 and ACS-RGO had a specific surface area and total pore volume of 507.4 and 389.0 m2/g, and 0.271 cm3/g and 0.273 cm3/g, respectively. ACS-RGO was superior for MG adsorption and the kinetic rate coefficient for ACS-RGO was ~ 7.2 times compared to MOF-5. For ACS-RGO, MG removal remained high (> 94%) in a wide range of pH. However, dye removal was pH-dependent for MOF-5 and increased from ~ 32% to ~ 67% by increasing pH from 4 to 12. Increasing dye concentration from 25 mg/L to 100 mg/L decreased adsorption by MOF-5 and ACS-RGO for ~ 30% and 7%, respectively. Dye removal was evident in a few tens of seconds after adding ACS-RGO at doses above 0.5 g/L. A significant loss of 46% in adsorption was observed by decreasing MOF-5 mass from 1 to 0.1 g/L. ACS-RGO removed MG in multilayer with an exceptional adsorption capacity of 1088.27 mg/g. In conclusion, ACS-RGO, and MOF-5 showed promising kinetic rates and adsorption capacities toward MG.
“…Antibiotics used in the treatment of some bacterial infections form a big pollutant class (Polianciuc et al 2020). Most of them are resistant to biological treatments and their concentration has been observed to show a gradual rise in both water and soil (Bonyadi et al 2021).…”
Metronidazole is well-known antibiotic which, globally, ranks high in popular usage. Therefore, traces of residues of this antibiotic were identified in aquatic bodies. A photosynthetic cyanobacterium, of the microalgae category, S. platensis, has been found to be efficient in the removal of this antibiotic. This study was performed to evaluate the efficiency of S. platensis in the removal of metronidazole from aqueous environments. To set up the optimum conditions for facilitating metronidazole removal, BBD model was employed. The experiment included the following parameters: the initial metronidazole level (10–80 mg/L), pH (4–10), contact time (10–60 min), and biomass dose (0.1–0.5 g/L). From the findings it was evident that S. platensis was able to remove 88.15% of the metronidazole under the following conditions: contact time 38.05 min, metronidazole level 35 mg/L, pH 7.71 and a biomass dose 0.3 g/L. The quadratic model revealed that metronidazole concentration was the chief variable that influenced its removal rate. MNZ removal rate was observed to follow the pseudo-second-order model and the Freundlich model. From the thermodynamic data it appeared that the process of metronidazole biosorption was spontaneous, exothermic and physical. The results of this study revealed that S. platensis could be used as an inexpensive and efficient biosorbent to remove the metronidazole from aqueous solutions.
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