Parametric optimization and structural feature analysis of humic acid extraction from lignite.

Humic acid (HA) is a complex organic compound made up of small molecules. A variety of raw materials are used to manufacture HA, due to which the structure and composition of HA vary widely. In this study, nitric acid oxidation of two coal samples from Lakhra (Pakistan) was followed by HA extraction using 2.5, 3.0 and 3.5% KOH solutions. The impact of different operating parameters such as; the effect of KOH concentrations, KOH-coal proportion, extraction time and pH range influencing the HA extraction efficiency was optimally investigated. Commercial HA applications possess numerous challenges, including valuable applications and sub-optimal extraction techniques. A significant limitation of conventional experimental methods is that they can only investigate one component at a time. It is necessary to improve the current processing conditions, this can only be achieved by modelling and optimization of the process conditions to meet market demands. A comprehensive evaluation and prediction of HA extraction using Response Surface Methodology (RSM) are also being reported for the first time in this study. The maximum HA extraction efficiency of 89.32% and 87.04% for coal samples 1 and 2 respectively was achieved with the lowest possible pH of 1.09 (coal sample 1) and 1(coal sample 2), which is remarkably lower as compared to those reported in the literature for conventional alkaline extraction process. The model was evaluated for two coal samples through the coefficient of determination (R2), Root Means Square Error (RMSE), and Mean Average Error (MEE). The results of RSM for coal sample 1 (R2 = 0.9795, RMSE = 4.784) and coal sample 2 (R2 = 0.9758, RMSE = 4.907) showed that the model is well suited for HA extraction efficiency predictions. The derived humic acid from lignite coal was analyzed using elemental analysis, UV-Visible spectrophotometry and Fourier-transformed infrared (FTIR) spectroscopy techniques. Scanning Electron Microscopy (SEM) was applied to analyze the morphological modifications of the extracted HA after treatment with 3.5% KOH solution. For agricultural objectives, such as soil enrichment, enhancing plant growth conditions, and creating green energy solutions, this acquired HA can be made bioactive. This study not only establishes a basis for research into the optimized extraction of HA from lignite coal, but it also creates a new avenue for the efficient and clean use of lignite.

Transformation of organic sulfur and its functional groups in nantong and laigang coal under microwave irradiation.

The microwave irradiation experiment of Nantong coal (NTC) and Laigang coal (LGC) has been carried out in a microwave oven and the transformation of organic sulfur and its functional groups was investigated via compact sulfur tester and Fourier transform infrared spectra. The dielectric properties of coal sample are also measured by an Agilent N5244A network analyzer. The result shows that a certain amount of organic sulfur in both NTC and LGC is transformed into iron sulfide, sulfate, and sulfur-containing gas after irradiation of microwave. The retention proportion of the three typical sulfur-containing functional groups in coal is ranking as: disulfide bond (S-S) > sulfinyl (SO) > sulfydryl (-SH), and such phenomenon has been explained by the first principle calculation based on the density functional theory. The calculation results of Fukui indices, electrostatic potential, and frontier orbital analysis indicate the reactivity of the SO and SS is lower than that of the -SH. The calculated bond dissociation enthalpies and bond dissociation times indicate the chemical bonds of -SH and S-S need more time to rupture than SO when microwave power is 1000 W. © 2019 Wiley Periodicals, Inc.

Construction and biological effects of a redox-enzyme dual-responsive lufenuron nano-controlled release formulation.

BACKGROUND: Pesticide formulations based on nanotechnology can effectively improve the efficiency of pesticide utilization and reduce pesticide residues in the environment. In this study, mesoporous silica nanoparticles containing disulfide bonds were synthesized by the sol-gel method, carboxylated and adsorbed with lufenuron, and grafted with cellulose to obtain a lufenuron-loaded nano-controlled release formulation (Luf@MSNs-ss-cellulose). RESULTS: The structure and properties of Luf@MSNs-ss-cellulose were characterized. The results showed that Luf@MSNs-ss-cellulose exhibits a regular spherical shape with 12.41% pesticide loading. The highest cumulative release rate (73.46%) of this pesticide-loaded nanoparticle was observed at 7 days in the environment of glutathione and cellulase, which shows redox-enzyme dual-responsive performance. As a result of cellulose grafting, Luf@MSNs-ss-cellulose had a small contact angle and high adhesion work on corn leaves, indicating good wetting and adhesion properties. After 14 days of spraying with 20 mg L-1 formulations in the long-term control efficacy experiment, the mortality of Luf@MSNs-ss-cellulose against Ostrinia furnacalis larvae (56.67%) was significantly higher than that of commercial Luf@EW (36.67%). Luf@MSNs-ss-cellulose is safer for earthworms and L02 cells. CONCLUSION: The nano-controlled release formulation obtained in this study achieved intelligent pesticide delivery in time and space under the environmental stimulation of glutathione and cellulase, providing an effective method for the development of novel pesticide delivery systems. © 2023 Society of Chemical Industry.

Influence of Fe2O3 on the Properties and Structure of Iron Coke.

Iron cokes were produced in an electrical furnace from a coal blend containing varying levels of added Fe2O3. The effects of Fe2O3 on the properties and structure of the iron coke were then investigated using the coke for metallurgy determination of mechanical strength, determination of coke reactivity and coke strength after the reaction, X-ray diffraction, Raman spectroscopy, and a method for quantitative analysis of the minerals in coal and coke. Further, the relationships between the properties and structures of iron coke samples were established. The results show that the addition of Fe2O3 can reduce the tumble strength, coke strength after the reaction, aromaticity, microcrystalline size, graphitization degree, crystalline volume, and carbon order degree of the iron coke and increase the abrasion resistance, coke reactivity index, and pulverization rate. Moreover, the degree of influence increases with increasing levels of added Fe2O3. The Fe2O3 is mainly transformed into metallic iron during the coking process, and part of metallic iron is converted into Fe3O4 during iron coke gasification. With an increasing Fe2O3 content, the trend of the change in the minerals from Fe to Fe3O4 becomes much more obvious, resulting in deeper influences on the iron coke thermal properties. There are obvious correlations among the iron coke reactivity and iron coke strength after the reaction and the crystalline volume, carbon order degree, and metallic iron content. It is concluded that the addition of Fe2O3 decreases the crystalline volume and carbon order degree and increases the metallic iron content, resulting in increases in abrasion resistance and coke reactivity and decreases in tumble strength and coke strength after the reaction.

Interfacial Behavior and Dechlorination Reaction of Water Droplet Impact on a Heated Extracted Titanium Tailing Surface.

The interfacial behaviors of the droplet impact on a heated extracted titanium tailing surface are studied experimentally. The effects of surface temperatures and Weber numbers on the droplet spreading characteristics are examined. The factors affecting the mass fraction and dechlorination ratio of extracted titanium tailings under the action of interfacial behavior have been researched by thermogravimetric analysis. The compositions and microstructures of extracted titanium tailings are characterized using X-ray fluorescence spectroscopy and scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS). The interfacial behaviors on the extracted titanium tailing surface are classified into four regimes, i.e., boiling-induced break-up, advancing recoiling, splash with a continuous liquid film, and splash with a broken film. The maximum spreading factors increase with the surface temperature and the Weber number. It is found that the surface temperature has a dominant influence on the spreading factors and interfacial effect, further affecting its chlorination reaction. SEM-EDS analysis revealed that the extracted titanium tailing particles are irregular shaped. There are some fine pores on the surface after the reaction. The main concentrations are Si, Al, and Ca oxides with a certain amount of C elements. The findings of this research provide a new pathway to utilize the extracted titanium tailings comprehensively.

Kinetic and equilibrium study of graphene and copper oxides modified nanocomposites for metal ions adsorption from binary metal aqueous solution.

Presently, the main cause of pollution of natural water resources is heavy metal ions. The removal of metal ions such as nickel (Ni2+) and cadmium (Cd2+) has been given considerable attention due to their health and environmental risks. In this regard, for wastewater treatment containing heavy metal ions, graphene oxide (GO) nanocomposites with metal oxide nanoparticles (NPs) attained significant importance. In this study, graphene oxide stacked with copper oxide nanocomposites (GO/CuO-NCs) were synthesized and characterized by Fourier transform infrared (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), and atomic force microscopy (AFM) analytical procedures. The prepared GO/CuO-NCs were applied for the removal of Ni2+ and Cd2+ ions from a binary metal ion system in batch and continuous experiments. The obtained results revealed that GO/CuO-NCs exhibited the highest removal efficiencies of Ni2+ (89.60% ± 2.12%) and Cd2+ (97.10% ± 1.91%) at the optimum values of pH: 8, dose: 0.25 g, contact time: 60 min, and at 50 ppm initial metal ion concentration in a batch study. However, 4 mL/min flow rate, 50 ppm initial concentration, and 2 cm bed height were proved to be the suitable conditions for metal ion adsorption in the column study. The kinetic adsorption data exhibited the best fitting with the pseudo-second-order model. The adsorption isotherm provided the best-fitting data in the Langmuir isotherm model. This study suggested that the GO/CuO nanocomposites have proved to be efficient adsorbents for Ni2+ and Cd2+ ions from a binary metal system.

Brain Perfusion Abnormalities after Radiotherapy Measured by 3-Dimensional Arterial Spin Labeling MRI and Correlations with Cognitive Impairment.

The purpose of this study was to use a 3-dimensional arterial spin labeling (3D ASL) magnetic resonance (MR) method to measure cerebral blood flow (CBF) before and after radiotherapy, and correlate changes with time after receiving radiotherapy and cognitive function. Patients with nasopharyngeal carcinoma receiving radiotherapy at our institution were recruited for the study. Participants were divided into three groups: Pre-radiotherapy control (PC) group, acute reaction period (ARP) group, and delayed reaction period (DRP)group. Thirty-four patients were included in the study. Compared with the PC group, the ARP group exhibited significantly decreased perfusion in the left anterior cingulate cortex (ACC) and right putamen, and increased perfusion in the right cerebellum (Crus 1), right inferior occipital gyrus, left lingual gyrus, left precuneus, and left calcarine gyrus. in the DRP group, increased perfusion was noted in the right cerebellum (Crus 1) and decreased perfusion in the left superior frontal gyrus. CBF differences were observed in several brain areas in the DRP group as compared to the ARP group (P < 0.001). Total Montreal Cognitive Assessment score, and subdomain language and delayed memory recall scores were significantly lower in the ARP and DRP groups than in the PC group (P < 0.05). Data suggest that ASL allows for non-invasive detection of radiation-induced whole-brain CBF changes, which is transient, dynamic and complicated and may be a factor contributing to cognitive impairment induced by radiotherapy for nasopharyngeal carcinoma.

Effects of different irradiators on the establishment of osteoradionecrosis model of rat mandible.

OBJECTIVES: To compare the effects of different irradiators on the establishment of osteoradionecrosis of jaw model (ORNJ) to explore an ideal modeling method. METHODS: A total of 33 adult SD rats were included and randomly divided into three groups according to the radiation equipment, namely, the blank control (CN, 3 rats), group A (linear accelerator irradiation, 15 rats), and group B (small-animal irradiator irradiation, 15 rats). Groups A and B were irradiated with daily fractions of 7, 8, and 9 Gy for 5 days and further divided into three subgroups as follows: group A35/B35, 35 Gy; group A40/B40, 40 Gy; and group A45/B45, 45 Gy. The left mandibular molars of the rats were extracted 1 week after irradiation. The rats were sacrificed 3 weeks after tooth extraction, and the mandible specimens were obtained for gross observation, micro-CT scanning, and histological detection to evaluate the success rate of modeling. RESULTS: At 3 weeks after dental extractions, complete gingival healing was found in the regions of dental extractions in groups A35 and A40. However, failed gingival healing and bone exposure were found in groups A45 and B. Hematoxylin and eosin staining showed necrotic bone of the irradiated mandible in groups A40, A45,and B, with success modeling rates of 40% in group A and 93.3% in group B. CONCLUSIONS: Small-animal irradiator irradiation is an ideal device for establishing ORNJ model.

Prediction of Structural and Electronic Properties of C and Cl2 Adsorbed on the Rutile TiO2 (110) Surface.

The study of the adsorption mechanism of C and Cl2 on the TiO2 (110) surface is of great significance for the formulation of the technological parameters in the fluidized chlorination process. Based on the first-principles calculations of density functional theory, the co-adsorption models of C and Cl2 on the rutile TiO2 (110) surface under different ratios were established. The adsorption structure, adsorption energy, charge density, and density of states were calculated and analyzed to reveal the reaction mechanism of C and Cl2 adsorbed on the rutile TiO2 (110) surface under different ratios. The results showed that with the increase of the ratio of C atoms in the reaction process, the complete adsorption possibility of Cl atoms on the surface of TiO2 (110) increased. Both Ti6c and C atoms were electron providers, while O3c and O2c were electron acceptors. The bonding interactions between C and O2c or C and Cl atoms were stronger, and the stabilities were higher. When C bonded with O2c and two Cl atoms, respectively, the overlapping peak width of C and O2c atoms was greater at the high energy level, and the electron delocalization was enhanced, and more electrons were transferred around the two Cl atoms. When C bonded with O2c and one Cl atom, respectively, the electron activity at the low energy level was higher, and the stability of the chemical bond was lower.

Effects of poplar addition on tar formation during the co-pyrolysis of fat coal and poplar at high temperature.

Three-stage absorption by butyl acetate was used to obtain tar components during the co-pyrolysis of fat coal and poplar at high temperature. The resulting tar yields were calculated relative to the fat coal and poplar blends. The tar components were characterized by gas chromatography-mass spectrometry, Fourier transform-infrared spectroscopy and 1H nuclear magnetic resonance spectroscopy. The effects of the added poplar on tar formation were then considered. The results show that the poplar-fat coal tar yield rose slightly when the poplar addition levels ranged from 4% to 12% and then increased much more at higher poplar addition levels. Oxygenated and aromatic compounds contributed greatly to the poplar-fat coal tar yield. The quantity of oxygenated components increased in the poplar blending ratio range from 4% to 12% and decreased as the ratio increased further, while the quantity of aromatic components showed the opposite trend. The influences of poplar addition levels on tar formation could be divided into two stages: (a) lighten the tar by stabilizing radicals at low poplar addition levels; (b) form heavier tar due to cross-linking reactions of the remaining radicals at high poplar addition levels. When the poplar addition levels ranged from 4% to 12%, due to synergistic effects, large amounts of free radicals and hydrogen from the co-pyrolysis of coal and poplar formed lighter stable compounds, which were then transported into the tar. Further, cross-linking reactions could be decreased because fewer free radicals and less hydrogen remained. As a result, the amount of PAHs declined, the tar yield rose slightly, the hydrocarbon-generating potential improved, the aliphatic chain length shortened, and the aromatic protons decreased. At higher blending ratios, excess radicals existed after stabilization due to the increasing poplar addition levels. These radicals underwent cross-linking reactions and produced PAHs, resulting in heavily increased tar yields, weakened hydrocarbon-generating potential, extended aliphatic chain lengths and increased aromatic protons.

CGRP may regulate bone metabolism through stimulating osteoblast differentiation and inhibiting osteoclast formation.

Calcitonin-gene-related peptide (CGRP) is a neuropeptide, which is widely distributed throughout the central and peripheral nervous systems. Numerous mechanisms underlying the action of CGRP in osteoblast-associated cells have been suggested for bone growth and metabolism. The present study was designed to closely investigate the osteoblast­ and osteoclast-associated mechanisms of the effect of CGRP administration on bone metabolism in primary osteoblasts. Primary osteoblasts were obtained from newborn rabbit calvaria and incubated with different concentrations of human CGRP (hCGRP), hCGRP and hCGRP (8­37), or without treatment as a control. Intracellular calcium (Ca2+) and cyclic adenosine monophosphate (cAMP) were detected following treatment, as well as the expression levels of osteoblast differentiation markers, including activating transcription factor­4 (ATF4) and osteocalcin (OC), and receptor activator of nuclear factor κB ligand (RANKL) and osteoprotegerin (OPG). The isolated primary osteoblasts were found to stain positively for ALP. hCGRP treatment had no significant effect on transient intracellular Ca2+ in the osteoblasts. Treatment of the osteoblasts with hCGRP led to elevations in the expression levels of cAMP, ATF4 and OPG, and downregulation in the expression of RANKL, in a dose­dependent manner. These effects were markedly reversed by the addition of hCGRP (8­37). The results of the present study demonstrated that CGRP administration not only stimulated osteoblast differentiation, as demonstrated by upregulated expression levels of ATF4 and OC in the hCGRP­treated osteoblasts, but also inhibited OPG/RANKL­regulated osteoclastogenesis. CGRP may act as a modulator of bone metabolism through osteoblast and osteoclast-associated mechanisms, which result in osteoblast formation with subsequent activation of bone formation.