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As an industrial energy plant, the whole parts of the sunflower crop were used for biofuel production through a biorefinery approach. Two scenarios were suggested for this biorefinery, i.e., using all parts of the crop separately and the whole residues as a mixture. The oil extracted from seeds was applied for biodiesel production through transesterification using a 6:1 methanol to oil molar ratio with 0.7% catalyst at 50 °C for 65 min. The process resulted in a 96.2% biodiesel yield with a heating value of 41.6 MJ/kg, corresponding to 84 kg biodiesel per ton of sunflower crop and 108.8 L gasoline-equivalent. Three physiochemical pretreatments were employed for structural modification of lignocellulosic residues, and the solid and liquid phases of the pretreatments were anaerobically digested for biomethane production. The effects of hot water (180 °C, 1 h), concentrated phosphoric acid (50 °C, 1 h, 85%), and sodium carbonate (142 °C, 18 min, 4%) pretreatments on composition, crystallinity, morphology, and biogas production of solid samples were evaluated. The highest methane yield of solid fractions was obtained from samples treated with phosphoric acid, and the seed cake showed the maximum yield of 342.7 N mL/g VS among all parts. Furthermore, the liquid phase of the hot water and alkaline pretreatments produced a high amount of biomethane, contrary to the acidic pretreatment. The overall mass balance showed that 11095.0 MJ/t energy (containing 346.7 L gasoline energy) was produced through the optimum biorefinery, where the untreated mixture and seed cake were used for biomethane production and the extracted oil for biodiesel production.

Often lab-scale adsorptive breakthrough experiments are conducted in an isothermal manner, whereas industrial-scale adsorption processes are near-adiabatic. In this work, a polyurethane (PUR) insulating column was manufactured to mimic large-scale non-isothermal behavior via laboratory-scale breakthrough tests. Breakthrough tests with a CO2/N2 gas mixture on zeolite 13X (∼5 g) were performed. A bed temperature increase of 62 °C and long cooling times were observed. When compared to a regular steel column, showing a temperature rise of only 12 °C, the column efficiency was approximately 20% lower due to adiabatic effects. The heat evacuated from the adsorbent bed via the column exhaust was used as a measure for the degree of adiabaticity. Up to 46% of the theoretical heat of adsorption could be detected at the PUR column exhaust compared to 4% at the steel column exhaust. The important difference between isothermal, non-isothermal and adiabatic limit behavior was demonstrated through breakthrough experiments and simulations.

Owing to its high porosity and tunable surface chemistry activated carbon (AC) is considered a promising material for CO2 adsorption. Functionalising porous materials by plasma is challenging but if successful, it could enhance the CO2 uptake capacity of AC via chemisorption. This work presents an in-depth analysis of the interactions between ammonia plasmas and the porous surface of AC monolithic samples. The treatment involved an ammonia based atmospheric-pressure dielectric barrier discharge and a low-pressure radio frequency plasma. Unique plasma reactor designs for treating 3-dimensional, electrically conducting and non-conducting monolithic structures at atmospheric pressure with versatile applications are presented. The plasma-surface interactions were analysed using emission spectroscopy and X-ray photoelectron spectroscopy. High surface N containing AC samples were then used to assess the treatment effect on the subsurface. A much lower although a still significant amount of N was found at depths of ∼30 µm. A simple fit of the results showed that the ratio of plasma species reaching the surface with higher to lower sticking probability was 4:1. A slight decrease in the microporosity of the plasma treated samples was found and attributed to pore blocking by the grafted N species. Plasma treated AC with high N showed an improved CO2 adsorption capacity of up to 14 % and selectivity against CH4 and N2 adsorption showed that the treatment was selective primarily towards CO2.

Morpholinium ionic liquids (ILs) using N-allyl-N-methylmorpholinium ([AMMorph]) cation in combination with acetate ([OAc]), formate ([OFo]), carbonate ([CO3]), and sulfate ([SO4]) anions were used for the pretreatment of triticale straw. The pretreatment was performed with various percentages of IL as well as water and dimethyl sulfoxide (DMSO) as cosolvents. These cosolvents reduced IL consumption and increased the ethanol efficiencies up to 90% and 76% after pretreatment with [AMMorph][OAc] or [AMMorph]2[CO3], respectively, and water cosolvent. Whereas the mixture of water and DMSO resulted in the maximum ethanol yields of 82% and 69% for [AMMorph][OFo] and [AMMorph]2[SO4], respectively. Among the studied IL-cosolvent combinations, the best solvent for the pretreatment of triticale straw was a mixture of [AMMorph][OAc] with 20% water to achieve highest ethanol production. The performance of this IL was further studied in terms of temperature and time, resulting in hydrolysis and ethanol yields of 99% and 94%, respectively. The results revealed that the anion plays a key role in the pretreatment efficiency and the organic anions, i.e., acetate and formate, had better performance in the presence of cosolvent compared with inorganic anions. Moreover, the amount and type of cosolvent for obtaining the highest yields are highly dependent on the anion type.

Spruce is the most resistant type of lignocellulosic material to anaerobic digestion. Different parts of spruce tree, i.e., leaves, wood, branches, bark, fruit, and mixtures of these parts, were pretreated using the leading pretreatments, i.e., concentrated phosphoric acid, dilute sulfuric acid, and ethanolic organosolv pretreatment, to improve biogas production. The pretreatment effects on methane yield from both solid and liquid fractions of the pretreatments were evaluated. Different parts of the tree showed different behaviors. The maximum methane yields from the pretreated solids were obtained after phosphoric acid pretreatment, which yielded methane yields of 211.7 and 225.5 mL per g volatile solids (VS) of pretreated spruce leaves and mixture, respectively. The improvements were related to opened-up structure, crystallinity reduction, and delignification. Sulfuric acid pretreatment improved biomethane yield from liquids, but not solids. Moreover, organosolv pretreatment improved the yield from solids, but not wood, bark, and the mixture. The maximum methane production yield was 245.3 NmL CH4/gVS which was obtained from the organosolv liquor of spruce leaves. The highest overall methane production (252.9 L per Kg) was gained from the whole solid and liquid fractions from organosolv pretreatment of leaves. This methane yield corresponded to 2.4-fold improvement compared to that of the untreated leaves (107 NmL CH4/gVS). Thus, leaves and branches are less recalcitrant parts and do not need severe pretreatment, while bark and wood are the most recalcitrant parts and required severe pretreatment like concentrated phosphoric acid. Moreover, the mixture of all parts also required severe pretreatment for efficient biogas production.

Direct, resistive or Joule heating of the adsorbent allows for the intensification of Thermal Swing Adsorption processes by reducing process cycle time and reducing heat losses. In this work, an electrically conductive activated carbon monolith was 3D-printed using a potassium silicate binder. The monolith was assessed for biogas upgrading, using Joule heating for regeneration of the monolith. The electrification of the 3D-printed monolith resulted in very rapid and homogenous heating, to 150 °C in less than 30 s at a potential of 8 V. Next, the monolith was subjected to cyclic adsorption-desorption experiments for CO2 capture from a synthetic biogas mixture (30 v% CO2 – 70 v% CH4). The main parameters in ESA, namely voltage, electrification time, purge conditions and an additional rinsing step were investigated by determining the impact on the heating, regeneration efficiency and purity. Increasing the voltage from 4 V to 8 V step is preferred for recovery (82–95%) as well as for energy consumption, as it increases the efficiency (27.1–28.4%). It was also found that using the same amount of purge gas, it is preferred to use a higher purge flow rate for a shorter time (100 Nml/min for 15 s) over a lower purge flow rate for a longer time (50 Nml/min for 30 s). This benefits both recovery (87.3% vs 84.0%) and purity (84.5% vs 83.4%). Lastly, the benefit of adding a rinse step to increase the purity was demonstrated, where having a rinse step prior to electrification allowed to augment the total purity from 58% to 81.2%, while the regeneration of the monolith was as efficient.

The use of microwave heating for the thermal regeneration of a porous carbon adsorbent in adsorptive carbon capture was evaluated. In this Microwave Swing Adsorption (MSA) process, a multimode microwave oven has been used to accelerate the desorption of CO2 after the adsorption of a CO2 / N2 (15/85 v/v) mixture. Starting from a commercial activated carbon (AC) material (MSP-20X), sorbent extrudates were prepared and loaded in a Teflon column. The heating of the sorbent bed inside the microwave (MW) cavity was characterised at different locations. Although the adsorption bed is not heated uniformly due to hot spots in the multimode MW cavity, flowing a purge gas reduces the non-uniform heating during the regeneration step. This study also reports that MSA regeneration achieves extremely fast total desorption (in 56 to 79 s), the quickest regeneration reported up to date in MSA, and very rapid desorption rates allowing swift adsorption–desorption cycles. This fast desorption is associated with the extremely high heating rates achieved (100 to 400 °C/min). We show that the desorption rate is faster when using higher powers at practically identical MW energy inputs. Complete CO2 desorption can be achieved at slightly longer durations when using 2-step MW heating. When comparing the MSA results with a reference TSA process, MSA outperforms TSA, due to the higher heating rates achieved by MSA. During eleven adsorption–desorption cycles, it is evidenced that the MSA process can regenerate the adsorption bed at a high reproducibility. The microporosity of the material remained intact during the MSA, revealing that localised heating and the high heating rates are not damaging the sorbent material.

Potato is the fourth most abundant crop harvested annually worldwide. Potato peel waste (PPW) is the main waste stream of potato-processing industries which is generated in large quantities and is a threat to the environment globally. However, owing to its compositional characteristics, availability, and zero cost, PPW is a renewable resource for the production of high-value bioproducts. Hence, this study provides a state-of-the-art overview of advancements in PPW valorization through biological and thermochemical conversions. PPW has a high potential for biofuel and biochemical generation through detoxification, pretreatment, hydrolysis, and fermentation. Moreover, many other valuable chemicals, including bio-oil, biochar, and biosorbents, can be produced via thermochemical conversions. However, several challenges are associated with the biological and thermochemical processing of PPW. The insights provided in this review pave the way toward a PPW-based biorefinery development, providing sustainable alternatives to fossil-based products and mitigating environmental concerns.

Zeolitic imidazolate framework-8 (ZIF-8) is one of the most stable Metal Organic Frameworks currently available, with promising properties in adsorption, separation and catalysis. Herein, we report a method for the rapid production of ZIF-8 crystals at room-temperature from methanolic solutions containing sodium acetate and metal salts. Of the different metal salts tested, copper nitrate presence prompted formation of cubic shaped ZIF-8 crystals within 5 min. Derived from this finding, an adaption of the synthesis route was implemented over copper foils and copper based metallic/non-metallic substrates, which yielded high quality shape- and size-controlled ZIF-8 crystal coatings. The outcomes also revealed a significant impact of sodium acetate as modulator and of copper ions released in the reaction media as triggering agent/co-modulator. Together these chemical species are understood to be involved in a multitude of coordination complex formation and deprotonation equilibria, thus largely determining the ZIF-8 crystal morphology and growth, especially near the copper releasing sites. Overall, this work presents an important platform for rapid and controlled synthesis of ZIF-8 crystals and coatings over metallic/non-metallic substrates, which can be adapted for advanced applications such as device integration.

In the production of hydrogen gas, the removal of hydrogen chloride (HCl) is of particular relevance for the chemical industry. Here we report the HCl removal performance of ZIF-8 metal organic framework demonstrated via fixed-bed (dynamic) measurements under process conditions. The measurements revealed an HCl removal capacity of 1.02 g/g, outperforming by far all traditional materials and other metal-organic framework previously tested. The ZIF-8, before and after the HCl contact, was characterized via SEM-EDX, XRD, TGA, ATR-FTIR, XPS and Raman spectroscopy. The results showed a dramatic change in textural, structural and chemical properties of ZIF-8 after HCl contact, where the MOF material undergoes a reaction and re-crystalizes into a salt complex.

The cocultivation of Clostridium acetobutylicum and Mucor indicus was evaluated for the first time to take the advantages of both microorganisms for fully exploiting the energy potential of the organic fraction of municipal solid waste (OFMSW), generating high yields of acetone-butanol-ethanol (ABE) and hydrogen through a biorefinery scheme. Unlike M. indicus, C. acetobutylicum can ferment unhydrolyzed starch and pentose sugars. However, the low biofuel titer through ABE fermentation makes the bioprocess uneconomical. The fungal-bacterial symbiosis led to high ethanol titer along with high butanol and hydrogen yields without the need for starch hydrolysis. The effects of most influencing factors, i.e., initial pH, bacterium to fungus biomass ratio, and solid loading, on ABE and hydrogen production were investigated. The fermentation of organosolv pretreated OFMSW hydrolysate at initial pH of 5.5 and solid loading of 5% with 1:1 bacterium to fungus biomass ratio produced 80.2 g butanol, 30.2 g acetone, 108.1 gethanol, and 96.3 L hydrogen from each kg raw OFMSW. From the bioenergy point of view, 7.2 MJ energy was generated, which was significantly higher than those obtained via the mono cultivation of C. acetobutylicum (6.2 MJ) and M. indicus (4.4 MJ), indicating the great potential of the fungal-bacterial cocultivation for bioenergy production from OFMSW. The economic potential of the cocultivated biorefinery was 0.16 $/kg OFMSW.

Shape engineering porous solids such as metal-organic frameworks (MOFs) into hierarchical structured adsorbents allows significant process intensification. Here we propose a facile approach to obtain a mouldable structured adsorbent with high loading of porous solids by employing a commercially available low-cost melamine sponge. As a case study, Mg-MOF-74 was synthesized in an aqueous media at room temperature and coated successfully over the melamine sponge, without any pre-treatment/additive, to yield a melamine sponge-based Mg- MOF-74 composite (Mg-MOF-74@MS). Even after multiple coating steps, the composite displayed remarkable compressibility, thus providing additional degrees of freedom in designing packed bed systems over other rigid adsorbent forms and structures. The dynamic gas separation capability of the prepared Mg-MOF-74@MS composite was demonstrated via breakthrough experiments with mixtures of 20% CO2 and 80% CH4 at 1 bar and 298 K. Owing to the spatial structure of melamine sponge, the composite retained the adsorption properties of Mg-MOF-74 for CO2 capture i.e., high dynamic capacity (5.07 mmol/g), high selectivity (>100), facile regeneration and performed better than binderless Mg-MOF-74 pellets in terms of mass transfer, unused bed length (LUB) and pressure drop (large permeability). Overall, these findings open an interesting field of research with melamine sponge-based MOF structured adsorbent as a potential candidate for gas-phase adsorption-based separation applications

The organic fraction of municipal solid waste (OFMSW) is a widely-available promising feedstock for biofuel production. However, the presence of different inhibitors originating from fruit and food/beverage wastes as well as recalcitrant lignocellulosic fractions hampers its bioconversion. This necessitates a pretreatment to augment the biodigestibility and fermentability of OFMSW. Hence, this review aims to provide the in-vogue inhibitory compound removal and pretreatment techniques that have been employed for efficient OFMSW conversion into biofuels, i.e., hydrogen, biogas, ethanol, and butanol. The techniques are compared concerning their mode of action, chemical and energy consumption, inhibitor formation and removal, economic feasibility, and environmental sustainability. This critique also reviews the existing knowledge gap and future perspectives for efficient OFMSW valorization. The insights provided pave the way toward developing energy-resilient cities while addressing environmental crises related to generating OFMSW.

The primary practices for waste textile management are landfill and incineration, generating serious environmental problems while they have a high potential for sustainable production of different green products. This study dealt with the economic analysis of bioethanol production and polyester recovery from waste textile through different scenarios. The pretreatment plays a key role in the biofuel production from waste textile and the most promising methods are pretreatment with NaOH, NaOH/urea, NaOH/thiourea, NaOH/urea/thiourea, and N-Methylmorpholine N-oxide, evaluated through scenarios 1 to 5, respectively. After pretreatment, the cotton part is enzymatically hydrolyzed and fermented through simultaneous saccharification and fermentation. Detailed simulations of the processes were carried out by Aspen Plus, and economic studies were conducted by Aspen Process Economic Analyzer for each scenario. The bioethanol production price were 0.447, 0.524, 0.624, 0.618, and 1.244 $/L for scenarios 1 to 5. The total capital investments required for scenarios 1 to 5 were 38.54, 38.60, 38.42, 38.57, and 39.35 M$, respectively. The profitability index for scenarios 1 to 5 were 2.17, 1.92, 1.61, 1.34, and 1.51. Therefore, the biorefinery based on producing bioethanol from waste textile is economically feasible. Moreover, In scenario 1, the payout period was the minimum time of 3.56 year, and the net return rate was 117.16. Sensitivity analysis also reveals that the price of waste textile has a significant impact on the profitability of the designed biorefinery. Scenario 5 is the most sensitive to variations in waste textile price; a 100% increase in the cost of waste textile increases the cost of producing bioethanol to more than 1.45 $/L, respectively.

The adsorptive vapour phase separation of 1-butanol from a synthetic ABE (acetone, 1-butanol, ethanol) mixture has been studied for the first time on a set of unidirectional small pore pure silica zeolites with ITW, MTF, RTH and STT structures with different pore size and topology. With this systematic approach, we provide insight into the structural and surface properties that can improve the vapour phase recovery of biobutanol. The influence of operation parameters, such as the temperature (40–80 °C), the total flow, and presence/absence of humidity and CO have been studied. For this application, adsorbents need to possess pore openings with one of their dimensions larger than 4.1 Å and cavities with diameters above 7 Å. Si-STT zeolite presents a remarkable selectivity towards 1-butanol, which is not affected by the presence of water or CO in the mixture or by an increase in the temperature. Si-STT results an excellent and robust adsorbent for this separation at conditions close to those of the headspace of the ABE fermenter, achieving purities of 90–93% at recoveries between 90 and 96%., The authors want to thank the Spanish Ministry of Science and Innovation and the Spanish Agency of Research for their funding via Project RTI2018-101784-B-I00. The Generalitat Valenciana, Conselleria d’Innovació, Universitats, Ciència y Societat Digital is acknowledged for their funding via project Prometeo/2021/077. EP-B acknowledges the Spanish Ministry of Education and Professional Training for the grant FPU15/01602 and the additional funding for the stay EST18/00213.