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.
In the title mol-ecular salt, C6H10N3O(+)·C7H5O3(-), the cation is protonated at the N atom lying between the amine and methyl substituents and the dihedral angle between the carboxyl group and its attached ring in the anion is 4.0 (2)°. The anion features an intra-molecular O-H⋯O hydrogen bond, which closes an S(6) ring. The cation and anion are linked by two N-H⋯O hydrogen bonds [R2(2)(8) motif] to generate an ion pair in which the dihedral angle between the aromatic rings is 8.34 (9)°. Crystal symmetry relates two ion pairs bridged by further N-H⋯O hydrogen bonds into a tetra-meric DDAA array. The tetra-mers are linked by pairs of C-H⋯O hydrogen bonds to generate [100] chains. Hirshfeld surface and fingerprint plot analyses are presented.
In the title chalcone derivative, C16H11ClF2O2, the enone group adopts an E conformation. The dihedral angle between the benzene rings is 0.47 (9)° and an intra-molecular C-H⋯F hydrogen bond closes an S(6) ring. In the crystal, mol-ecules are linked into a three-dimensional network by C-H⋯O hydrogen bonds and aromatic π-π stacking inter-actions are also observed [centroid-centroid separation = 3.5629 (18) Å]. The inter-molecular inter-actions in the crystal structure were qu-anti-fied and analysed using Hirshfeld surface analysis.
The title compound, C18H20ClN3S, is a functionalized triazoline-3-thione derivative. The benzene ring is almost perpendic-ular to the planar 1,2,4-triazole ring [maximum deviation = 0.007 (1) Å] with a dihedral angle of 89.61 (5)° between them and there is an adamantane substituent at the 3-position of the triazole-thione ring. In the crystal, N-H⋯S hydrogen-bonding inter-actions link the mol-ecules into chains extending along the c-axis direction. The crystal packing is further stabilized by weak C-H⋯π inter-actions that link adjacent chains into a two-dimensional structure in the bc plane. The crystal studied was an inversion twin with a 0.50 (3):0.50 (3) domain ratio.
The title aza-stilbene derivative, C14H13NO2 {systematic name: (E)-2-[(4-meth-oxy-benzyl-idene)amino]-phenol}, is a product of the condensation reaction between 4-meth-oxy-benzaldehyde and 2-amino-phenol. The mol-ecule adopts an E conformation with respect to the azomethine C=N bond and is almost planar, the dihedral angle between the two substituted benzene rings being 3.29 (4)°. The meth-oxy group is coplanar with the benzene ring to which it is attached, the Cmeth-yl-O-C-C torsion angle being -1.14 (12)°. There is an intra-molecular O-H⋯N hydrogen bond generating an S(5) ring motif. In the crystal, mol-ecules are linked via C-H⋯O hydrogen bonds, forming zigzag chains along [10-1]. The chains are linked via C-H⋯π inter-actions, forming a three-dimensional structure.
In the title compound, C25H26N2O2S2, the central CN2S2 atoms are almost coplanar (r.m.s. deviation = 0.0058 Å). One phenyl ring clearly lies to one side of the central plane, while the other is oriented in the plane but splayed. Despite the different relative orientations, the phenyl rings form similar dihedral angles of 64.90 (3) and 70.06 (3)° with the central plane, and 63.28 (4)° with each other. The benzene ring is twisted with respect to the central plane, forming a dihedral angle of 13.17 (7)°. The S2C=N, N-N and N-N=C bond lengths of 1.2919 (19), 1.4037 (17) and 1.2892 (19) Å, respectively, suggest limited conjugation over these atoms; the configuration about the N-N=C bond is E. An intra-molecular O-H⋯N hydrogen bond is noted. In the crystal, phen-yl-meth-oxy C-H⋯O and phen-yl-phenyl C-H⋯π inter-actions lead to supra-molecular double chains parallel to the b axis. These are connected into a layer via meth-yl-phenyl C-H⋯π inter-actions, and layers stack along the a axis, being connected by weak π-π inter-actions between phenyl rings [inter-centroid distance = 3.9915 (9) Å] so that a three-dimensional architecture ensues.
Bio-electrochemical systems (BESs) are the microbial systems which are employed to produce electricity directly from organic wastes along with some valuable chemicals production such as medium chain fatty acids; acetate, butyrate and alcohols. In this review, recent updates about value-added chemicals production concomitantly with the production of gaseous fuels like hydrogen and methane which are considered as cleaner for the environment have been addressed. Additionally, the bottlenecks associated with the conversion rates, lower yields and other aspects have been mentioned. In spite of its infant stage development, this would be the future trend of energy, biochemicals and electricity production in greener and cleaner pathway with the win-win situation of organic waste remediation. Henceforth, this review intends to summarise and foster the progress made in the BESs and discusses its challenges and outlook on future research advances.
Catalytic steam gasification of palm kernel shell is investigated to optimize operating parameters for hydrogen and syngas production using TGA-MS setup. RSM is used for experimental design and evaluating the effect of temperature, particle size, CaO/biomass ratio, and coal bottom ash wt% on hydrogen and syngas. Hydrogen production appears highly sensitive to all factors, especially temperature and coal bottom ash wt%. In case of syngas, the order of parametric influence is: CaO/biomass>coal bottom ash wt%>temperature>particle size. The significant catalytic effect of coal bottom ash is due to the presence of Fe2O3, MgO, Al2O3, and CaO. A temperature of 692°C, coal bottom ash wt% of 0.07, CaO/biomass of 1.42, and particle size of 0.75mm are the optimum conditions for augmented yield of hydrogen and syngas. The production of hydrogen and syngas is 1.5% higher in the pilot scale gasifier as compared to TGA-MS setup.
Cysteine is one of the major intermediate products of cellular amino-acid metabolism. It is a semi-essential amino acid for protein synthesis. Besides, it is also employed in the regulation of major endogenous anti-oxidant molecule i.e., reduced glutathione (GSH). Further, it is a precursor of multiple sulfur-containing molecules like hydrogen sulfide, lanthionine, taurine, coenzyme A and biotin. It is also one of the key molecules for post-translational modifications of various cellular proteins. In physiological conditions, it is employed in the sulfhydration process and plays a key role in the physiology modification of the inflammatory process in various organs, including the neurological system. The catabolism of cysteine is regulated by cysteine dioxygenase enzyme activity. The dysregulated conditions of cysteine and cysteine-associated hydrogen sulfide metabolism are widely employed in the acceleration of the neurodegenerative process. Moreover, the upregulation of cysteine and hydrogen sulfide synthesis occurs via the reverse trans-sulfuration process. This process helps to manage the worsening of a pathological condition of a cellular system. Moreover, it is also employed in the accumulation of homocysteine contents. Further, both cysteine and homocysteine molecules are widely accepted as biomarkers for various types of diseases. Therefore, the targets involved in the regulation of cysteine have been considered as valid targets to treat various disorders like cardiac disease, ischemic stroke, diabetes, cancer, and renal dysfunction.
This study reports on the synthesis of bi-metal compound (BMC) adsorbents based on commercial coconut activated carbon (CAC), surface-modified with metal acetate (ZnAc2), metal oxide (ZnO), and the basic compounds potassium hydroxide (KOH) and sodium hydroxide (NaOH). The adsorbents were then characterized by scanning electron microscopy and elemental analysis, microporosity analysis through Brunauer-Emmett-Teller (BET) analysis, and thermal stability via thermogravimetric analysis. Adsorption-desorption test was conducted to determine the adsorption capacity of H2S via 1 L adsorber and 1000 ppm H2S balanced 49.95% for N2 and CO2. Characterization results revealed that the impregnated solution homogeneously covered the adsorbent surface, morphology, and properties. The adsorption test result reveals that the ZnAc2/ZnO/CAC_B had a higher H2S breakthrough adsorption capacity and performed at larger than 90% capability compared with a single modified adsorbent (ZnAc2/CAC). Therefore, the synthesized BMC adsorbents have a high H2S loading, and the abundance and low cost of CAC may lead to favorable adsorbents in H2S captured.
The gas sweetening process removes hydrogen sulfide (H2S) in an acid gas removal unit (AGRU) to meet the gas sales' specification, known as sweet gas. Monitoring the concentration of H2S in sweet gas is crucial to avoid operational and environmental issues. This study shows the capability of artificial neural networks (ANN) to predict the concentration of H2S in sweet gas. The concentration of N-methyldiethanolamine (MDEA) and Piperazine (PZ), temperature and pressure as inputs, and the concentration of H2S in sweet gas as outputs have been used to create the ANN network. Two distinct backpropagation techniques with various transfer functions and numbers of neurons were used to train the ANN models. Multiple linear regression (MLR) was used to compare the outcomes of the ANN models. The models' performance was assessed using the mean absolute error (MAE), root mean square error (RMSE), and coefficient of determination (R2). The findings demonstrate that ANN trained by the Levenberg-Marquardt technique, equipped with a logistic sigmoid (logsig) transfer function with three neurons achieved the highest R2 (0.966) and the lowest MAE (0.066) and RMSE (0.122) values. The findings suggested that ANN can be a reliable and accurate prediction method in predicting the concentration of H2S in sweet gas.
The novel phosphonium-based ionic liquid (IL), triphenyl methyl phosphonium tosylate ([TPMP][Tos]), has been synthesized and applied as a phase transfer catalyst (PTC) in the ultrasound-assisted oxidative desulfurization (UAODS). Oxidation of model fuel (MF) containing dibenzothiophene (DBT) was carried out using an equimolar mixture of H2O2-CH3COOH as an oxidant at 40-70 °C in the presence of IL. The sulfur compound is converted into polar sulfone, and the maximum desulfurization efficiency was examined. The effect of process parameters such as reaction temperature, reaction time, molar ratio of oxidant to sulfur (n(O/S)), and the mass ratio of ionic liquid to model fuel (m(IL/MF)) was studied, and the conditions for maximizing the DBT conversion rate were found. Maximum conversion (> 99%) was obtained at a temperature of 70 °C with m(IL/MF) of 0.8. The oxidation reactivity of various sulfur compounds was studied at different time intervals. To verify the effect of ionic liquid and ultrasound irradiation, extractive desulfurization (EDS), oxidative desulfurization (ODS), and UAODS in the presence of IL were carried out. The experimental results show that the UAODS process gives the highest desulfurization efficiency. A kinetic study was performed to estimate the rate constant and the order of oxidation reaction.
To formulate a dental bleaching agent with strawberry extract that has potent bleaching properties and antimicrobial efficacy. Enamel specimens (3 × 3 × 2 mm3) were prepared. Quaternary Ammonium Silane (CaC2 enriched) was homogenized with fresh strawberries: Group 1: supernatant strawberry (10 g) extract
The depletion of fossil fuel sources and increase in energy demands have increased the need for a sustainable alternative energy source. The ability to produce hydrogen from microalgae is generating a lot of attention in both academia and industry. Due to complex production procedures, the commercial production of microalgal biohydrogen is not yet practical. Developing the most optimum microalgal hydrogen production process is also very laborious and expensive as proven from the experimental measurement. Therefore, this research project intended to analyse the random time series dataset collected during microalgal hydrogen productions while using various low thermally pre-treated palm kernel expeller (PKE) waste via machine learning (ML) approach. The analysis of collected dataset allowed the derivation of an enhanced kinetic model based on the Gompertz model amidst the dark fermentative hydrogen production that integrated thermal pre-treatment duration as a function within the model. The optimum microalgal hydrogen production attained with the enhanced kinetic model was 387.1 mL/g microalgae after 6 days with 1 h thermally pre-treated PKE waste at 90 °C. The enhanced model also had better accuracy (R2 = 0.9556) and net energy ratio (NER) value (0.71) than previous studies. Finally, the NER could be further improved to 0.91 when the microalgal culture was reused, heralding the potential application of ML in optimizing the microalgal hydrogen production process.
Energy security and environmental measurements are incomplete without renewable energy; therefore, there is a dire need to explore new energy sources. Hence, this study aimed to measure the wind power potential to generate renewable hydrogen (H2), including its production and supply cost. This study used first-order engineering model and net present value to measure the levelized cost of wind-generated renewable hydrogen by using the data source of the Pakistan Meteorological Department and State Bank of Pakistan. Results showed that the use of surplus wind and renewable hydrogen energy for green economic production is suggested as an innovative project option for large-scale hydrogen use. The key annual running expenses for hydrogen are electricity and storage costs, which have a significant impact on the costs of renewable hydrogen. The results also indicated that the project can potentially cut carbon dioxide (CO2) pollution by 139 million metric tons and raise revenue for wind power plants by US$2998.52 million. The renewable electrolyzer plants avoided CO2 at a rate of US$24.9-36.9/ton under baseload service, relative to US$44.3/ton for the benchmark. However, in the more practical mid-load situation, these plants have significant benefits. Further, the wind-generated renewable hydrogen delivers 6-11% larger annual rate of return than the standard CO2 catch plant due to their capacity to remain running and supply hydrogen to the consumer through periods of plentiful wind and heat. Also, the measured levelized output cost of hydrogen (LCOH) was US$6.22/kgH2, and for the PEC system, it was US$8.43/kgH2. Finally, it is a mutually agreed consensus among environmental scientists that the integration of renewable energy is the way forward to increase energy security and environmental performance by ensuring uninterrupted clean and green energy. This application has the potential to address Pakistan's urgent issues of large-scale surplus wind- and solar-generated energy, as well as rising energy demand.
Hydrogen peroxide (H2 O2 ) is a primary reactive oxygen species (ROS) that can act as a chemical signal in developing and progressing serious and life-threatening diseases like cancer. Due to the stressful nature of H2 O2 , there is an urgent need to develop sensitive analytical approaches to be applied to various biological matrices. Herein, a portable point-of-care electrochemical system based on MXene-Co3 O4 nanocomposites to detect H2 O2 in different cancer cell-lines is presented. The developed sensor is affordable, disposable, and highly selective for H2 O2 detection. This approach achieves a dynamic linear range of 75 µm with a LOD of 0.5 µm and a LOQ of 1.6 µm. To improve the practical application, the level of ROS is evaluated both in cancer cell lines MDA-MB-231 and DU145, respectively, to breast and prostate cancers, and in healthy HaCat cells. Moreover, the same cancer cells are treated with transforming growth factor-β1, and MXene-Co3 O4 modified strip is capable to monitorROS variation. The results are satisfactory compared with the cellular ROS fluorescent assay based on DCFH/DCFH-DA. These results open new perspectives for real-time monitoring of cancer progression and the efficacy of the therapy.
Palm oil mill effluent (POME) is a highly contaminating wastewater due to its high chemical oxygen demand (COD) and biochemical oxygen demand (BOD). Conventional treatment methods require longer residence time (10-15 days) and higher operating cost. Owing to this, finding a suitable and efficient method for the treatment of POME is crucial. In this investigation, ultrasound cavitation technology has been used as an alternative technique to treat POME. Cavitation is the phenomenon of formation, growth and collapse of bubbles in a liquid. The end process of collapse leads to intense conditions of temperature and pressure and shock waves which assist various physical and chemical transformations. Two different ultrasound systems i.e. ultrasonic bath (37 kHz) and a hexagonal triple frequency ultrasonic reactor (28, 40 and 70 kHz) of 15 L have been used. The results showed a fluctuating COD pattern (in between 45,000 and 60,000 mg/L) while using ultrasound bath alone, whereas a non-fluctuating COD pattern with a final COD of 27,000 mg/L was achieved when hydrogen peroxide was introduced. Similarly for the triple frequency ultrasound reactor, coupling all the three frequencies resulted into a final COD of 41,300 mg/L compared to any other individual or combination of two frequencies. With the possibility of larger and continuous ultrasonic cavitational reactors, it is believed that this could be a promising and a fruitful green process engineering technique for the treatment of POME.
This study evaluated the effectiveness of Fenton's technique for the treatment of semi-aerobic landfill leachate collected from Pulau Burung Landfill Site (PBLS), Penang, Malaysia. The Fe2+ or Fe3+ as catalyst and H2O2 as oxidizing agent are commonly used for the classical Fenton's reaction. In present study, the effect of operating conditions such as pH, reaction time, molar ratio, agitation rate, feeding mode and Fenton reagent concentrations which are important parameters that affect the removal efficiencies of Fenton method were investigated. Under the most favorable conditions, the highest removals of 58.1 and 78.3% were observed for COD and color, respectively. In general, the best operating conditions were pH = 3, Fe = 560 mg L(-1), H2O2 = 1020 mg L(-1), H2O2/Fe2+ molar ratio = 3, agitation rate = 400 rpm and reaction time = 120 minutes. The results highlighted that stepwise addition of Fenton's reagent was more effective than adding the entire volume in a single step. Excessive hydrogen peroxide and iron have shown scavenging effects on hydroxyl radicals and reduced degradation of refractory organics in the landfill leachate.
Path analysis has been largely used in marketing research but has recently been applied in an environmental management context. This study evaluated the potential of path analysis in identifying the influence of moisture content on odor from decomposing food waste. Food waste with varying moisture content was monitored for odor concentration, microbial population density, oxygen uptake rate, volatile fatty acids, ammonia, and hydrogen sulfide. These various parameters were later analyzed using SmartPLS 3.0 software to produce the path analysis model using simultaneous equation modeling. Results indicate that odor concentration of food waste was not directly affected by moisture content (not significant, t-statistical 1.46 hydrogen sulfide (significant, t-statistical 3.79 > 1.96) and subsequently odor. In order to manage food waste-related odors, it is recommended that the waste be kept at a moisture content lower than 40%. This is especially critical if prolonged storage is unavoidable.
Food waste and food processing wastes which are abundant in nature and rich in carbon content can be attractive renewable substrates for sustainable biohydrogen production due to wide economic prospects in industries. Many studies utilizing common food wastes such as dining hall or restaurant waste and wastes generated from food processing industries have shown good percentages of hydrogen in gas composition, production yield and rate. The carbon composition in food waste also plays a crucial role in determining high biohydrogen yield. Physicochemical factors such as pre-treatment to seed culture, pH, temperature (mesophilic/thermophilic) and etc. are also important to ensure the dominance of hydrogen-producing bacteria in dark fermentation. This review demonstrates the potential of food waste and food processing waste for biohydrogen production and provides a brief overview of several physicochemical factors that affect biohydrogen production in dark fermentation. The economic viability of biohydrogen production from food waste is also discussed.