The phosphate adsorption onto ACF-La was strongly dependent on pH value and the main mechanism involved in adsorption process varied with the change of solution pH. Moreover, high temperature was in ...favor of the adsorption process. The background electrolyte (NaCl) not only reduced the uptake amount but also increased the effect of intraparticle diffusion on adsorption of phosphate onto ACF-La. Display omitted
► The feasibility of phosphate removal using ACF-La as an adsorbent was investigated. ► The effect of pH on the phosphate adsorption mechanism was identified. ► The effect of ionic strength on the mass transport of phosphate ions onto the ACF-La was examined. ► The behavior of adsorption process by means of evaluating activation energy and thermodynamic parameters was studied.
Phosphate removal from polluted water is crucial to preventing eutrophication. Herein, we present the investigation on phosphate adsorption in aqueous solutions by using lanthanum-doped activated carbon fiber (ACF-La). Various batch sorption conditions, e.g., pH, ionic strength, and temperature were tested, and the adsorption mechanisms were discussed. The sorption capacity of ACF-La was higher in acidic solutions than that in basic ones, suggesting that the Lewis acid–base interaction gradually dominated the adsorption process with the increase in pH values. The degree of phosphate removal decreased with the enhancement of the ionic strength of the solution, meaning that the adsorption of phosphate on ACF-La was strongly dependent on ionic strength. Employing the pseudo first- and second-order, and intra-particle diffusion models to evaluate the adsorption kinetics of phosphate onto ACF-La indicated that the second-order model best fits the experimental data. The presence of chloride ion in solutions increased the effect of intra-particle diffusion on the adsorption of phosphate onto ACF-La but reduced the overall rate of the adsorption. The thermodynamic parameters were determined which revealed the feasibility, spontaneity, and endothermic nature of adsorption.
A novel adsorbent, lanthanum hydroxide-doped activated carbon fiber (ACF-LaOH), was prepared by the ultrasound-assisted chemical precipitation method for phosphate removal from waste water. Ligands ...exchange, electrostatic interactions and Lewis acid–base interaction are the three main mechanisms for phosphate adsorption. The ligands exchange, electrostatic interactions would become weaker and the Lewis acid–base interaction be strengthened with the increase of pH values giving rise to the decrease of adsorption amount. Display omitted
► The preparation and performance of ACF-LaOH for phosphate removal were investigated. ► The adsorption mechanisms were investigated by SEM, FT-IR and pH analysis. ► Ligands exchange, electrostatic interactions and Lewis acid–base interaction are the 3 mechanisms. ► Ligands exchange, electrostatic interactions are weaker with the increase of pH values.
A novel adsorbent, lanthanum hydroxide-doped activated carbon fiber (ACF-LaOH), has been prepared by the ultrasound-assisted chemical precipitation method for phosphate removal from waste water. Based on the single-factor method, response surface methodology (RSM) by using a Box–Behnken design (BBD) was applied to assess the mutual interactions and effects between the three factors and the optimized preparation conditions (concentration of La3+ of 0.11mol/L, ultrasonic power at 206W and ultrasonic time of 7.3min). Adsorption kinetics and isothermal adsorption studies showed that the pseudo second-order model and the Langmuir isotherm fitted the experimental data quite well, indicating that the adsorption process was mainly through chemical interactions. At last whereas most importantly, the phosphate adsorption mechanism was investigated by analyzing the scanning electron microscopy (SEM), fourier transform infrared (FT-IR) spectroscopy and the relationship between the adsorption amount and the pH of phosphate solution. The results demonstrated that ligands exchange, electrostatic interactions and Lewis acid–base interaction were the three main mechanisms for phosphate adsorption. The ligands exchange and electrostatic interactions became weaker, but the Lewis acid–base interaction was strengthened with the increase of pH values giving rise to the decrease of adsorption amount.
When biogenic methane produced in marine shallow sediments flows laterally into hydrate stable zones, there is likely to be formation of disperse stratigraphic-diffusive hydrate reservoirs that ...generally appear thin-bedded and disseminated. The stratigraphic-diffusive layers are also potential industrial exploitation targets because they have moderate abundance, wide distribution, and convenient mining maneuverability. After success of the second trial production in Shenhu area of South China Sea, it is urgent for us to find out the evolution dynamics of the stratigraphic-diffusive hydrate system which is widespread along oceanic continental slopes. Here, the Pearl River Mouth Basin in the northern slope area of South China Sea as a typical passive margin was selected to probe the principles of the accumulation mechanism and distribution pattern of stratigraphic-diffusive methane hydrates, determine the optimal degree of aggregation and spatial extension, and thus evaluate the potential recovery value. Based on the composite stratigraphic sequence, we theoretically described the occurrence characteristics of this type of stratigraphic-diffusive hydrate reservoirs. A two-dimensional model that coupled sedimentation process, fluid flow and reaction kinetics was designed to gauge the influence of engineering geological conditions and other controlling factors since the Pliocene (5.3 Ma) in this system. Several key parameters (including porosity, temperature, salt, and hydrate content) at three different moments, 5 Ma ago, 1.5 Ma ago and at present, were exhibited. The impacts of geothermal gradient and kinetic reaction coefficient on the evolution process were also discussed. Finally, the methane generated from local particulate organic carbons and different start time was used to verify the rationality of this theoretical approach. Our two-dimensional model clearly depicted the occurrence and accumulation characteristics of local stratigraphic-diffusive hydrates, disclosed the exploration value and exhibited the exploitation possibility.
•Theoretically characterizes occurrence of slope stratigraphic-diffusive hydrates.•Comprehensively couples sedimentation, flow and reaction along slope surface.•Definitely demonstrates evolution process of MH reservoirs in Shenhu slope area.•Reasonably verifies hydrate geological applicability of this two-dimensional model.•Clearly discloses necessary exploration value and potential extraction possibility.
Phosphate removal from wastewater is very important for the prevention of eutrophication. Adsorption of phosphate from water was investigated using activated carbon fiber loaded with lanthanum oxide ...(ACF-La) as a novel adsorbent. The effects of variables (La/ACF mass ratio, impregnation time, activation time, and activation temperature) have been studied by the single-factor method. Response surface methodology (RSM), based on three-variable-three-level Box–Behnken design (BBD), was employed to assess the individual and collective effects of the main independent parameters on the phosphate removal. The optimal conditions within the range studied for preparing ACF-La were found as follows: La/ACF mass ratio of 11.78%, activation time of 2.5
h and activation temperature at 650
°C, respectively. The phosphate removal using the ACF-La prepared under the optimal conditions was up to 97.6% even when the phosphate concentration in water was 30
mg
P/L, indicating that ACF-La may be an effective adsorbent. The results from Fourier transform infrared (FT-IR) spectroscopy and change of pH values associated with the adsorption process revealed that the probable mechanism of phosphate ions onto ACF-La was not only ion exchange and coulomb interaction, but also a result of Lewis acid–base interaction due to La–O coordination bonding.
Alkali-activated materials, a new kind of low-carbon cement, have received extensive attention. While in order to obtain excellent functions, the modification of alkali-activated materials by ...nano-materials has become one of the important research directions of alkali-activated materials. Therein, the hydration property, mechanical properties, and action mechanism of the alkali-activated slag with and without graphene oxide (GO) were analyzed and evaluated. Results showed the compressive strength of mortar decreased at 3 days and 28 days by adding GO. While the flexural strength of mortar cured for different ages increased with increasing GO content, and the flexural strength increasing rate reached up to 15.94% at 28 days, thus, the toughening effect of GO was significant. GO accelerated the hydration process of alkali-activated slag because the functional groups offered nucleation sites to induce the generation of more hydration products. Furthermore, the addition of GO increased the number of harmless pores and reduced the pore size, but also introduced a large number of harmful pores, resulting in the reduction of compressive strength.
The global prevalence of type 2 diabetes mellitus (T2DM) and Alzheimer's disease (AD) is rapidly increasing, revealing a strong association between these two diseases. Currently, there are no ...curative medication available for the comorbidity of T2DM and AD. Ceramides are structural components of cell membrane lipids and act as signal molecules regulating cell homeostasis. Their synthesis and degradation play crucial roles in maintaining metabolic balance
, serving as important mediators in the development of neurodegenerative and metabolic disorders. Abnormal ceramide metabolism disrupts intracellular signaling, induces oxidative stress, activates inflammatory factors, and impacts glucose and lipid homeostasis in metabolism-related tissues like the liver, skeletal muscle, and adipose tissue, driving the occurrence and progression of T2DM. The connection between changes in ceramide levels in the brain, amyloid β accumulation, and tau hyper-phosphorylation is evident. Additionally, ceramide regulates cell survival and apoptosis through related signaling pathways, actively participating in the occurrence and progression of AD. Regulatory enzymes, their metabolites, and signaling pathways impact core pathological molecular mechanisms shared by T2DM and AD, such as insulin resistance and inflammatory response. Consequently, regulating ceramide metabolism may become a potential therapeutic target and intervention for the comorbidity of T2DM and AD. The paper comprehensively summarizes and discusses the role of ceramide and its metabolites in the pathogenesis of T2DM and AD, as well as the latest progress in the treatment of T2DM with AD.
To obtain the fundamental data of CO2/N2 gas mixture hydrate formation kinetics and CO2 separation and sequestration mechanisms, the gas hydrate formation process by a binary CO2/N2 gas mixture ...(50:50) in fine sediments(150–250 μm) was investigated in a semibatch vessel at variable temperatures(273, 275, and 277 K)and pressures (5.8–7.8 MPa). During the gas hydrate reaction process, the changes in the gaseous phase composition were determined by gas chromatography. The results indicate that the gas hydrate formation process of the binary CO2/N2 gas mixture in fine sediments can be reduced to two stages. Firstly, the dissolved gas containing a large amount of CO2 formed gas hydrates, and then gaseous N2 participated in the gas hydrate formation. In the second stage, all the dissolved gas was consumed. Thus, both gaseous CO2 and N2 diffused into sediment. The first stage in different experiments lasted for 5–15 h, and >60% of the gas was consumed in this period. The gas consumption rate was greater in the first stage than in the second stage. After the completion of gas hydrate formation, the CO2 content in the gas hydrate was more than that in the gas phase. This indicates that CO2 formed hydrate easily than N2 in the binary mixture. Higher operating pressures and lower temperatures increased the gas consumption rate of the binary gas mixture in gas hydrate formation.
Coal combustion flue gas contains CO2, a greenhouse gas and driver of climate change. Therefore, CO2 separation and removal is necessary. Fortunately, 5A zeolites are highly porous and can be used as ...a CO2 adsorbent. In addition, they act as nuclei for hydrate formation. In this work, a composite technology, based on the physical adsorption of CO2 by 5A zeolite and hydrate-based gas separation, was used to separate CO2/N2 gas mixtures. The influence of water content, temperature, pressure, and particle size on gas adsorption and CO2 separation was studied, revealing that the CO2 separation ability of zeolite particles sized 150–180 μm was better than that of those sized 380–830 μm at 271.2 K and 273.2 K. When the zeolite particles were 150–180 μm (type-B zeolite) with a water content of 35.3%, the gas consumption per mole of water (ngas/nH2O ) reached the maximum, 0.048, and the CO2 separation ratio reached 14.30%. The CO2 molar concentration in the remaining gas phase (xCO2gas) was lowest at 271.2 K in the type-B zeolite system with a water content of 47.62%. Raman analysis revealed that CO2 preferentially occupied the small hydrate cages and there was a competitive relationship between N2 and CO2.
The precipitation and re-austenitization behavior of α-ferrite during thermal rebound process of casting slab are crucial to the austenite grain size distribution. Accurately obtaining austenite ...grain size distribution plays an important guiding role for avoiding the formation of slab cracks and effectively improving the quality of steel. In this work, a quantitative model to calculate α-ferrite precipitation at different temperatures has been constructed by employing high-temperature expansion test and peak area method. On this basis, a prediction model for the austenite grain size distribution of casting slab in the thermal rebound process has been theoretically derived with consideration of the α-ferrite precipitation and re-austenitization. Then, the accuracy of the quantitative model for α-ferrite precipitation and the prediction model for austenite grain size distribution have been evaluated by high-temperature quenching experiments. The results show that the maximum error between the calculation values of the prediction model and the experimental values is only 3.67 %, which can reliably predict the austenite grain size distribution of slab under different phase fractions of precipitated α-ferrite and initial austenite grain sizes. When the phase fraction of precipitated α-ferrite reaches about 70 %, the average grain size after re-austenitization comes to nearly 50 % of the initial size, which achieves the best refining effect. The reduction in initial austenite grain size is beneficial to the refinement of austenite grain after thermal rebound. Reasonable control of thermal rebound temperature and multiple cycles of phase transformation are effective means of obtaining austenite microstructure with smaller average grain size and more uniform distribution.
Supersulfated cement (SSC) is a green and environmentally friendly material that contains limited or no clinkers, with low-hydration heat release and favorable sulfate corrosion resistance. However, ...SSC requires modification because its poor mechanical property has restricted its promotion and application to a certain extent. Mix proportion design and mechanical properties of Bayer red mud and water glass-modified SSC were explored in this study, and the results were discussed by microanalysis. Results showed that the increase of red mud content prolongs the setting time of SSC, thereby indicating that early-stage mechanical properties (within 3 days), especially ultraearly-stage mechanical properties (within hours), need further improvement. However, mechanical properties of SSC mortar at different stages improve after three days, and further improve with the simultaneous addition of water glass and red mud. The optimal mix proportion of SSC obtained using Taguchi method is presented as follows: slag (70 wt.%), gypsum (15 wt.%), OPC (5 wt.%), red mud (10 wt.%), and water glass with a modulus of 1.8 (2.0 wt.%). Meanwhile, the compressive strength of specimen at this mix proportion reaches 42.12 MPa at 28 d. Mechanical properties improve because system alkalinity is further enhanced, additional gel products are generated, and the hardened body presents a tight binding state due to the simultaneous addition of red mud and water glass.
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