Lignocellulosic biomass contains lignin, an aromatic and oxygenated substance and a potential method for lignin utilization is achieved through catalytic conversion into useful phenolic and aromatic monomers. The application of monometallic catalysts for lignin hydrogenolysis reaction remains one of the major reasons for the underutilization of lignin to produce valuable chemicals. Monometallic catalysts have many limitations such as limited catalytic sites for interacting with different lignin linkages, poor catalytic activity, low lignin conversion, and low product selectivity. It is due to lack of synergy with other metallic catalysts that can enhance the catalytic activity, stability, selectivity, and overall catalytic performance. To overcome these limitations, works on the application of bimetallic catalysts that can offer higher activity, selectivity, and stability have been initiated. In this review, cutting-edge insights into the catalytic hydrogenolysis of lignin, focusing on the production of phenolic and aromatic monomers using bimetallic catalysts within an internal hydrogen donor solvent are discussed. The contribution of this work lies in a critical discussion of recent reported findings, in-depth analyses of reaction mechanisms, optimal conditions, and emerging trends in lignin catalytic hydrogenolysis. The specific effects of catalytic active components on the reaction outcomes are also explored. Additionally, this review extends beyond current knowledge, offering forward-looking suggestions for utilizing lignin as a raw material in the production of valuable products across various industrial processes. This work not only consolidates existing knowledge but also introduces novel perspectives, paving the way for future advancements in lignin utilization and catalytic processes.
Biodiesel commercialization is questionable due to poor brake thermal efficiency. Biodiesel utilization should be improved with the addition of fuel additives. Hydrogen peroxide is a potential fuel additive due to extra hydrogen and oxygen content, which improves the combustion process. In this experimental study, biodiesel has been produced from Jatropha oil employing catalyzed transesterification homogeneously to examine its influence on the performance and emissions at engine loads with 1500 rpm utilizing a four-stroke single-cylinder diesel engine. D60B40 (having 60% diesel and 40% biodiesel) and D60B30A10 (60% diesel, 30% biodiesel and 10% hydrogen peroxide (H2O2)), are the fuel mixtures in the current study. The addition of H2O2 reduces emissions and enhances the combustion process. This effect occurred due to the micro-explosion of the injected fuel particles (which increases in-cylinder pressure and heat release rate (HRR)). An increase of 20% in BTE and 25% reduction in BSFC for D60B30A10 was observed compared to D60B40. Significant reduction in emissions of HC up to 17.54%, smoke by 24.6% CO2 by 3.53%, and an increase in NOx was noticed when the engine is operated with D60B30A10. The HRR increased up to 18.6%, ID reduced by 10.82%, and in-cylinder pressure increased by 8.5%. Test runs can be minimized as per Taguchi's design of experiments. It is possible to provide the estimates for the full factorial design of experiments. Exhaust gas temperature standards are evaluated and examined for all fuel blends.
The aim of this study was to investigate the influence of some environmental factors on bacterial metabolism. Fermentative hydrogen production by C. acetobutylicum, using glucose as the substrate. The effect of initial pH (4-8), inoculum size (1-20% (v/v)) and glucose concentration (1-30 g L(-1)) on hydrogen production were studied. The optimum cultivation temperature for hydrogen production was at 30 degrees C. The results show that substrate concentration and inoculum size resulted in hydrogen yield (Y(P/S)) of 391 mL g(-1) glucose utilized with maximum hydrogen productivity of 77.5 mL/L/h. Higher substrate concentration or inoculum size adversely affects hydrogen production, which decreases hydrogen yield by 15% to 334 mL g(-1) glucose utilized when 30% (v/v) inoculum size was used. The use of 30 g L(-1) substrate concentration resulted in a 75% decrease to 97 mL g(-1) glucose supplied. Concluded that proper Xo/So enhanced the hydrogen production.
In the title compound, C18H18N2O2, the pyrazole ring has a twisted conformation on the CH-CH2 bond. The tolyl ring and the 4-meth-oxy-phenyl ring are inclined to the mean plane of the pyrazole ring by 4.40 (9) and 86.22 (9)°, respectively, while the two aromatic rings are inclined to one another by 88.75 (9)°. In the crystal, mol-ecules are linked via bifurcated C-H⋯(O,O) hydrogen bonds and C-H⋯π inter-actions, forming sheets lying parallel to the ab plane.
In the title iso-quinoline-1,3,4-trione derivative, C18H9NO5, the five-membered ring of the indane fragment adopts an envelope conformation with the nitro-gen-substituted C atom being the flap. The planes of the indane benzene ring and the iso-quinoline-1,3,4-trione ring make a dihedral angle of 82.06 (6)°. In the crystal, mol-ecules are linked into chains extending along the bc plane via C-H⋯O hydrogen-bonding inter-actions, enclosing R 2 (2)(8) and R 2 (2)(10) loops. The chains are further connected by π-π stacking inter-ations, with centroid-to-centroid distances of 3.9050 (7) Å, forming layers parallel to the b axis.
In the title compound, C13H16N2O2S, the pyrrolidine ring has a twisted conformation on the central -CH2-CH2- bond. Its mean plane is inclined to the 4-meth-oxy-benzoyl ring by 72.79 (15)°. In the crystal, mol-ecules are linked by N-H⋯O and C-H⋯O hydrogen bonds to the same O-atom acceptor, forming chains along [001]. The chains are linked via slipped parallel π-π inter-actions [inter-centroid distance = 3.7578 (13) Å], forming undulating slabs parallel to (100).
The environmental footprints of H2productionviacatalytic gasification of wheat straw using straw-derived biochar catalysts were examined. The functional unit of 1 kg of H2was adopted in the system boundaries, which includes 5 processes namely biomass collection and pre-treatment units (P1), biochar catalyst preparation using fast pyrolysis unit (P2), two-stage pyrolysis-gasification unit (P3), products separation unit (P4), and H2distribution to downstream plants (P5). Based on the life-cycle assessment, the hot spots in this process were identified, the sequence was as follows: P4 > P2 > P1 > P3 > P5. The end-point impacts score for the process was found to be 93.4017 mPt. From benchmarking analysis, the proposed straw-derived biochar catalyst was capable of offering almost similar catalytic performance with other metal-based catalysts with a lower environmental impact.
A compact ultrawideband (UWB) antenna based on a hexagonal split-ring resonator (HSRR) is presented in this paper for sensing the pH factor. The modified HSRR is a new concept regarding the conventional square split-ring resonator (SSRR). Two HSRRs are interconnected with a strip line and a split in one HSRR is introduced to increase the electrical length and coupling effect. The presented UWB antenna consists of three unit cells on top of the radiating patch element. This combination of UWB antenna and HSRR gives double-negative characteristics which increase the sensitivity of the UWB antenna for the pH sensor. The proposed ultrawideband antenna metamaterial sensor was designed and fabricated on FR-4 substrate. The electrical length of the proposed metamaterial antenna sensor is 0.238 × 0.194 × 0.016 λ, where λ is the lowest frequency of 3 GHz. The fractional bandwidth and bandwidth dimension ratio were achieved with the metamaterial-inspired antenna as 146.91% and 3183.05, respectively. The operating frequency of this antenna sensor covers the bandwidth of 17 GHz, starting from 3 to 20 GHz with a realized gain of 3.88 dB. The proposed HSRR-based ultrawideband antenna sensor is found to reach high gain and bandwidth while maintaining the smallest electrical size, a highly desired property for pH-sensing applications.
Biohydrogen as one of the most appealing energy vector for the future represents attractive avenue in alternative energy research. Recently, variety of biohydrogen production pathways has been suggested to improve the key features of the process. Nevertheless, researches are still needed to overcome remaining barriers to practical applications such as low yields and production rates. Considering practicality aspects, this review emphasized on anaerobic membrane bioreactors (AnMBRs) for biological hydrogen production. Recent advances and emerging issues associated with biohydrogen generation in AnMBR technology are critically discussed. Several techniques are highlighted that are aimed at overcoming these barriers. Moreover, environmental and economical potentials along with future research perspectives are addressed to drive biohydrogen technology towards practicality and economical-feasibility.
The synthesis of Janus nanosheets using κ-carrageenan (κ-Ca) as a green template endows a greener and more straightforward method compared to traditional approaches of using wax template. We hypothesize that the hydrogen bonding interaction between κ-Ca and graphene oxide (GO) allows partial masking of GO's single facet, paving the way for the asymmetric modification of the exposed surface. GO is first encapsulated within the porous hydrogel matrix formed by κ-Ca to isolate one of the facets. The exposed surface was then selectively hydrophobized to produce an amphiphilic asymmetrically modified graphene oxide (AMGO). The properties of AMGO synthesized under different κ-Ca/GO ratios were studied. The κ-Ca/GO interactions and the properties of GO and AMGO were investigated and characterized. AMGO was successfully produced with a yield of 90.37 % under optimized synthesis conditions. The separation of κ-Ca and AMGO was conducted without organic solvents, and the κ-Ca could be subsequently recovered. Furthermore, the porous hydrogel matrix formed by κ-Ca and GO exhibited excellent shape-retaining properties with high thermal tolerance of up to 50 °C. Given these benefits, this newly developed method endows sustainability and open the possibility of formulating more flexible material synthesis protocols.
In the modern world, wheat, a vital global cereal and the second most consumed, is vulnerable to climate change impacts. These include erratic rainfall and extreme temperatures, endangering global food security. Research on hydrogen-rich water (HRW) has gained momentum in plant and agricultural sciences due to its diverse functions. This study examined the effects of different HRW treatment durations on wheat, revealing that the 4-h treatment had the highest germination rate, enhancing potential, vigor, and germination indexes. This treatment also boosted relative water content, root and shoot weight, and average lengths. Moreover, the 4-h HRW treatment resulted in the highest chlorophyll and soluble protein concentrations in seeds while reducing cell death. The 4-h and 5-h HRW treatments significantly increased H2O2 levels, with the highest NO detected in both root and shoot after 4-h HRW exposure. Additionally, HRW-treated seeds exhibited increased Zn and Fe concentrations, along with antioxidant enzyme activities (CAT, SOD, APX) in roots and shoots. These findings suggest that HRW treatment could enhance wheat seed germination, growth, and nutrient absorption, thereby increasing agricultural productivity. Molecular analysis indicated significant upregulation of the Dreb1 gene with a 4-h HRW treatment. Thus, it shows promise in addressing climate change effects on wheat production. Therefore, HRW treatment could be a hopeful strategy for enhancing wheat plant drought tolerance, requiring further investigation (field experiments) to validate its impact on plant growth and drought stress mitigation.
Crystallization of the ionic liquid 3,3'-dimethyl-1,1'-(1,4-phenylenedimethylene)diimidazolium bis(tetrafluoroborate), C(16)H(20)N(4)(2+).2BF(4)(-), (I), from its solution in water has permitted the first single-crystal study of an imidazolium-based ionic liquid having a tetrafluoroborate ion as counter-ion. Despite the expectation that the anion would not participate in nonclassical hydrogen bonding, the ionic liquid features C-H...F hydrogen bonds. The dication lies about a center of inversion. The ionic liquid 3,3'-di-n-butyl-1,1'-(1,4-phenylenedimethylene)diimidazolium bis(trifluoromethanesulfonate), C(22)H(32)N(4)(2+).2CF(3)SO(3)(-), (II), features both C-H...F and C-H...O hydrogen bonds.
The current study investigated the effects of S2O8(2-) and S2O8(2-)/H2O2 oxidation processes on the biodegradable characteristics of an anaerobic stabilized leachate. Total COD removal efficiency was found to be 46% after S2O8(2-) oxidation (using 4.2 g S2O8(2-)/1g COD0, at pH 7, for 60 min reaction time and at 350 rpm shaking speed), and improved to 81% following S2O8(2-)/H2O2 oxidation process (using 5.88 g S2O8(2-) dosage, 8.63 g H2O2 dosage, at pH 11 and for 120 min reaction time at 350 rpm). Biodegradability in terms of BOD5/COD ratio of the leachate enhanced from 0.09 to 0.1 and to 0.17 following S2O8(2-) and S2O8(2-)/H2O2 oxidation processes, respectively. The fractions of COD were determined before and after each oxidation processes (S2O8(2-) and S2O8(2-)/H2O2). The fraction of biodegradable COD(bi) increased from 36% in raw leachate to 57% and 68% after applying S2O8(2-) and S2O8(2-)/H2O2 oxidation, respectively. As for soluble COD(s), its removal efficiency was 39% and 78% following S2O8(2-) and S2O8(2-)/H2O2 oxidation, respectively. The maximum removal for particulate COD was 94% and was obtained after 120 min of S2O8(2-)/H2O2 oxidation. As a conclusion, S2O8(2-)/H2O2 oxidation could be an efficient method for improving the biodegradability of anaerobic stabilized leachate.
In the ternary title compound, catena-poly[[silver(I)-mu-ethylenediamine-kappa(2)N:N'] 3-nitrobenzoate monohydrate], [[Ag(C(2)H(8)N(2))](C(7)H(4)NO(4)) x H(2)O](n), the Ag atom is bicoordinated in a linear configuration by two different N atoms from two symmetry-related ethylenediamine ligands, thus giving linear polymeric chains with an [-Ag-N-C-C-N-](n) backbone running parallel to the a axis. In the crystal packing, these linear chains are interconnected by N-H...O and O-H...O hydrogen bonds to form layers parallel to the ab plane.
In the presence of guest 2,4'-bpy molecules or under acidic conditions, three compounds, [Cd(4,4'-bpy)(2)(H(2)O)(2)](ClO(4))(2).(2,4'-bpy)(2).H(2)O (1), [Zn(4,4'-bpy)(2)(H(2)O)(2)](ClO(4))(2).(2,4'-bpy)(2).H(2)O (2), and [Cu(4,4'-bpy)(2)(H(2)O)(2)](ClO(4))(4).(4,4'-H(2)bpy) (3), were obtained from the reactions of the metal salts and 4,4'-bpy in an EtOH-H(2)O mixture. 1 has a 2-D square-grid network structure, crystallizing in the monoclinic space group P2/n, with a = 13.231(3) Å, b = 11.669(2) Å, c = 15.019(3) Å, beta = 112.82(3) degrees, Z = 2; 2 is isomorphous with 1, crystallizing in the monoclinic space group P2/n, with a = 13.150(3) Å, b = 11.368(2) Å, c = 14.745(3) Å, beta = 110.60(3) degrees, Z = 2. The square grids superpose on each other into a channel structure, in which each layer consists of two pairs of shared edges, perfectly square-planar with an M(II) ion and a 4,4'-bpy at each corner and side, respectively. The square cavity has dimensions of 11.669(2) x 11.788(2) and 11.368(2) x 11.488(2) Å for 1 and 2, respectively. Every two guest 2,4'-bpy molecules are clathrated in each hydrophobic host cavity and are further stabilized by pi-pi stacking and hydrogen bonding interactions. The NMR spectra clearly confirm that both 1 and 2 contain 4,4'-bpy and 2,4'-bpy molecules in a 1:1 ratio, which have stacking interaction with each other in the solution. 3 crystallizes in the orthorhombic space group Ibam, with a = 11.1283(5) Å, b = 15.5927(8) Å, c = 22.3178(11) Å, Z = 4. 3 is made up of two-dimensional square [Cu(4)(4,4'-bpy)(4)] grids, where the square cavity has dimensions of 11.13 x 11.16 Å. Each [4,4'-H(2)bpy](2+) cation is clathrated in a square cavity and stacks with one pair of opposite edges of the host square cavity in an offset fashion with the face-to-face distance of ca. 3.95 Å. Within each cavity, the [4,4'-H(2)bpy](2+) cation forms twin three-center hydrogen bonds with two pairs of ClO(4)(-) anions. The results suggest that the guest 2,4'-bpy molecules and protonated [4,4'-H(2)bpy](2+) cations present in the reaction systems serve as structure-directing templates in the formation of the crystal structures and exclude self-inclusion of the networks having larger square cavities.
This study highlights biohydrogen production enrichment through NiO and CoO nanoparticles (NPs) inclusion to dark fermentation of rice mill wastewater using Clostridium beijerinckii DSM 791. NiO (~26 nm) and CoO (~50 nm) NPs were intrinsically prepared via facile hydrothermal method with polyhedral morphology and high purity. Dosage dependency studies revealed the maximum biohydrogen production characteristics for 1.5 mg/L concentration of both NPs. Biohydrogen yield was improved by 2.09 and 1.9 folds higher for optimum dosage of NiO and CoO respectively, compared to control run without NPs. Co-metabolites analysis confirmed the biohydrogen production through acetate and butyrate pathways. Maximum COD reduction efficiencies of 77.6% and 69.5% were observed for NiO and CoO inclusions respectively, which were higher than control run (57.5%). Gompertz kinetic model fitted well with experimental data of NPs assisted fermentation. Thus, NiO and CoO inclusions to wastewater fermentation seems to be a promising technique for augmented biohydrogen production.
Within a small, interconnected reaction network, orthogonal recognition processes drive the assembly and replication of a [2]rotaxane. Rotaxane formation is governed by a central, hydrogen-bonding-mediated binding equilibrium between a macrocycle and a linear component, which associate to give a reactive pseudorotaxane. Both the pseudorotaxane and the linear component undergo irreversible, recognition-mediated 1,3-dipolar cycloaddition reactions with a stoppering maleimide group, forming rotaxane and thread, respectively. As a result of these orthogonal recognition-mediated processes, the rotaxane and thread can act as auto-catalytic templates for their own formation and also operate as cross-catalytic templates for each other. However, the interplay between the recognition and reaction processes in this reaction network results in the formation of undesirable pseudorotaxane complexes, causing thread formation to exceed rotaxane formation in the current experimental system. Nevertheless, in the absence of competitive macrocycle-binding sites, realization of a replicating network favoring formation of rotaxane is possible.
In the title thio-semicarbazone compound, C18H18ClN3S, the CN3S residue is almost planar (r.m.s. deviation = 0.0031 Å) and forms dihedral angles of 65.99 (7) and 34.60 (10)° with the phenyl and chloro-benzene rings, respectively; the dihedral angle between the aromatic rings is 85.13 (8)°. The conformation about the C=N bond is Z, and that about the C=C bonds is E. The imine N and ethyl N atoms are syn and are linked by an eth-yl-imine N-H⋯N hydrogen bond. This H atom also forms an inter-molecular hydrogen bond to the thione S atom, resulting in a supra-molecular helical chain propagating along the b axis. The chains are consolidated into a three-dimensional architecture by phenyl-C-H⋯Cl contacts and weak π-π inter-actions between centrosymmetrically related chloro-benzene rings [inter-centroid distance = 3.9127 (15) Å].
The mol-ecule of the title Schiff base compound, C14H14N2O2, displays an E conformation with respect the imine C=N double bond. The mol-ecule is approximately planar, with the dihedral angle formed by the planes of the pyridine and benzene rings being 5.72 (6)°. There is an intra-molecular hydrogen bond involving the phenolic H and imine N atoms.
In the title mol-ecular salt, 2C6H10N3O+·C8H4O42-, the N atom of each of the two 2-amino-4-meth-oxy-6-methyl-pyrimidine mol-ecules lying between the amine and methyl groups has been protonated. The dihedral angles between the pyrimidine rings of the cations and the benzene ring of the succinate dianion are 5.04 (8) and 7.95 (8)°. Each of the cations is linked to the anion through a pair of N-H⋯O(carboxyl-ate) hydrogen bonds, forming cyclic R22(8) ring motifs which are then linked through inversion-related N-H⋯O hydrogen bonds, giving a central R24(8) motif. Peripheral amine N-H⋯O hydrogen-bonding inter-actions on either side of the succinate anion, also through centrosymmetric R22(8) extensions, form one-dimensional ribbons extending along [211]. The crystal structure also features π-π stacking inter-actions between the aromatic rings of the pyrimidine cations [minimum ring centroid separation = 3.6337 (9) Å]. The inter-molecular inter-actions were also investigated using Hirshfeld surface studies and two-dimensional fingerprint images.