Solid Phase Concentration Research Articles

Sedimentary controls on arsenic distribution in meander-belt deposits of the Po Valley, Italy.

Geogenic arsenic in soils and aquifers is a threat to public health, which can be mitigated by improving our understanding of arsenic distribution in natural environments. In alluvial plains traversed by meandering rivers, solid- and aqueous-phase arsenic concentrations tend to vary across sedimentary deposits accumulated by different processes linked to river morphodynamics: mud-prone and commonly organic-rich abandoned-channel fills arising from meander cut-off act as local sources of arsenic, which can be transferred to adjacent point-bar deposits related to meander growth. Meanwhile, spatial variability in arsenic contamination may also arise from variations in sediment provenance across a fluvial landscape, and from inherent downstream changes in a fluvial system. Yet, the relative importance of facies and provenance as controls on arsenic concentrations in fluvial sediments still needs to be assessed. Through integrated analyses of geomorphological, sedimentological and geochemical data, this study examines the spatial variability in arsenic distribution from deposits of the late Holocene channel belt of the Po River, Italy. Three study areas were investigated along a >100km stretch of channel belt to evaluate the possible roles of downstream changes in river behaviour and sediment supply from variably arsenic-rich catchments. Sedimentological controls on solid-phase arsenic concentrations are recognized at the scales of both elementary lithologies (facies) and depositional sub-environments, highlighting the roles of morphologically recognizable abandoned-channel fills as sources of arsenic that can be mobilized via groundwater flow and become trapped in point-bar elements. Although solid-phase arsenic concentrations are dominantly related to the presence of organic matter and clay, local arsenic enrichment may be related to arsenic advection across meander-belt sediments, a process that is itself controlled by petrophysical heterogeneity. No evident relationship is seen between arsenic concentrations and point-bar facies distributions related to styles of meander morphodynamic evolution. Yet, limited variability across the study areas suggests that the facies control remains dominant over a potential provenance control related to catchment integration. The results help elucidate the role of sedimentary heterogeneity in the distribution of arsenic in sediments, soils and aquifers, in the Po Valley and other analogous fluvial environments.

Amelioration of different acidic soils in China using seafood shell biochars.

Soil acidification limits crop and pasture production and leads to the degradation of agroecosystems. A substantial volume of seafood shells are discarded each year, which creates enormous environmental and social pressures. In this study, the anaerobic pyrolysis characteristics of four types of seafood shells (clam, scallop, oyster, and mussel) were evaluated. Then, outdoor pot experiments using canola (Brassica napus L.) were conducted and the soil solution was collected in situ to determine the pH, organic matter, nutrient content, and aluminum (Al) species in soil liquid and solid phase. Finally, the relationships between the growth of canola and the concentration of phytotoxic Al were investigated to evaluate the amelioration efficacy and mechanism of seafood shell biochars applied to three typical acidic soils in China. The results showed that seafood shell biochars pyrolyzed under 800°C anaerobic conditions had characteristics of inorganic and organic amendments. The addition of 2gkg-1 four seafood shell biochars pyrolyzed at 800°C could increase pH of three kinds of severely acidified soils and soil solutions to more than 5.0, and adding 4gkg-1 could increase they to more than 6.0. After adding 4gkg-1 four seafood shell biochars in Oxisol-GD, Ultisol-AH and Ultisol-JX, the Al concentration of soil solution decreased by more than 89%, 88% and 80%, respectively; the effects were similar to lime. The application of four seafood shell biochars promoted the transformation of water-soluble Al and exchangeable Al in acidic soils into organically bound Al, adsorbed hydroxyl Al, and more stable Al, thus greatly reducing the concentration of Al in soil solution; this improved the growth of canola and increased the yield.

INFLUENCE OF HUMIC ACIDS ON RHEOLOGICAL PROPERTIES OF COMPOSITE SUSPENSIONS BASED ON PYROCARBON

The possibility of utilizing technical pyrocarbon obtained as a result of pyrolysis of waste tires into composite suspension fuel was investigated. It was determined that the surface of unmodified pyrocarbon has a positive surface charge in the pH range of 2-10. The addition of humic acid causes a change in the surface charge of pyrocarbon and an overcharge of the surface. The influence of stabilizer additives on the rheological properties of composite suspension fuel based on pyrocarbon was studied. Carboxymethyl cellulose, OP-10, and humic acids were used as stabilizers. It is shown that the composite suspension fuel based on pyrocarbon has a synergistic effect of the addition of OP-10 with sodium humate to reduce the effective viscosity and fluidity of suspensions. A composite suspension fuel consisting of [0.5% C3 + 0.25% OP + 3% HA] at a solid phase concentration of 51.7% was proposed. The effective viscosity of the obtained suspensions does not exceed 0.9 Pa‧sec, and the sedimentation stability is 28-30 days. This allows us to recommend the obtained suspensions as liquid suspension fuel for liquid fuel units.

Study on the particle dynamic characteristics in a centrifugal pump based on an improved computational fluid dynamics-discrete element model

To accurately investigate the solid–liquid flow mechanisms within the pump, this study employs an improved Computational Fluid Dynamics-Discrete Element Method (CFD-DEM) approach to examine the solid–liquid interactions in a centrifugal pump. First, the improved CFD-DEM is introduced, focusing on turbulence dissipation near the wall and velocity reconstruction. Then, a comparison is made between the CFD-DEM's performance before and after the enhancements. Finally, an analysis is conducted on how the dynamic characteristics of particles within the pump vary under different solid phase concentration conditions. The study revealed that the particle distribution from the corrected CFD-DEM aligns more closely with the experimental results. At a 2% concentration under the design conditions, the head error was reduced by 0.476%, while the efficiency error decreased by 0.076%. Additionally, as the solid phase concentration increased, there was a corresponding rise in the impact power loss of the particles, dissipative power loss, collision frequency, peak values of particle collisions, and the degree of overlap during these collisions. The comparison revealed that the pressure gradient force has the most significant impact on particle motion. As the pressure gradient force increases, the shear power dissipation of the particles also rises. For solid phase concentrations ranging from 1% to 4%, the average shear power variation during the computation period is between 4.28 × 10−6 W and 5.68 × 10−6 W. As the solid phase concentration increases, the volume fraction of the solid phase distribution on the component wall also gradually rises. These findings provide valuable insights for enhancing the accuracy of research on solid–liquid flow in centrifugal pumps.

ECVT imaging and CFD simulation of particle flow in a 90° bend

Gas-solid two-phase flow characteristics in a 90° bend within a pneumatic conveying system are critical for design and performance optimization, impacting conveying efficiency and system safety. Electrical Capacitance Volumetric Tomography (ECVT) and Computational Fluid Dynamics (CFD) simulations were employed in this study to investigate the flow characteristics in the bend. The ECVT system for bends was validated through static tests. A setup with a 36 mm inner diameter was constructed for high-speed 3D imaging of 0.9 mm quartz particles. Flow patterns, solid-phase concentration, particle velocity spectra, and mass flow rate were analyzed under various gas velocities. The Euler-Lagrange method and SST K-ω model were used to simulate particle flow and pipe wall erosion numerically. Results indicate diverse flow patterns across different gas velocities, where moderate turbulence enhances efficiency and limits erosion. This study offers an experimental basis for predicting and controlling particle motion, providing scientific guidance for optimizing pneumatic systems.

Experimental study on the unsteady evolution mechanism of centrifugal pump impeller wake under solid–liquid two-phase conditions: Impact of particle concentration

To study the spatiotemporal evolution process of particle wakes behind the impeller in the centrifugal pump, this paper utilized high-speed photography to capture the particle motion characteristics under different solid-phase particle concentrations (1%, 1.5%, and 2%). First, this paper studies the changes in hydraulic performance of the centrifugal pump under solid–liquid two-phase flow conditions. It then introduces the evolution process of the impeller particle wake, comparing the differences in particle wake evolution under varying solid-phase concentrations. Finally, the impact of the solid-phase concentration on the wear of the volute's partitions is investigated. This study found that as the solid-phase particle concentration increases, the hydraulic performance of the pump gradually declines. Under the design conditions, when the solid-phase concentration increases by 0.5%, the efficiency of the centrifugal pump decreases by 0.56% and 0.35%. There is mutual transport of particles between adjacent wakes, and the movement of particle wakes within the volute passage is not equidistant over time. As the solid-phase particle concentration increases, wake cutting occurs at the volute partitions, and there is a significant solid–liquid separation between the particle wakes. The spatial evolution of the particle wakes is significantly influenced by the solid-phase concentration. Wear at the volute partitions intensifies with increasing solid-phase concentration and is also affected by changes in the particle wakes. The research results provide a basis for further exploration of the solid–liquid two-phase flow dynamics within centrifugal pumps.

KH571 construct interfacial molecular bridge in calcium silicate/TMPTA/HDDA scaffolds for improving mechanical properties, biodegradability and photopolymerization

Digital Light Processing (DLP) offers the potential for personalized bone implants. Within this method, the interfacial bonding capacity of inorganic/organic materials and the solid-phase content of the slurry emerge as primary factors influencing scaffolds mechanical properties. In this research, KH571 was applied to establish an interfacial “molecular bridge”, adopting in situ coupling technology to forge stable covalent bonds between calcium silicate (CSi) and KH571. Chemical grafting, surface photografting, and photopolymerization techniques were then utilized to construct a photo-crosslinked network by CSi-KH571-TMPTA/HDDA slurry, thereby transforming the weak physical connections at the interface into strong chemical bonds. Consequently, the curing capacity and mechanical properties of the scaffolds were enhanced. Further control grain size, crystal phase transition, and shrinkage of CSi-KH571 scaffolds, post-treatment sintering processes were employed, resulting in scaffolds with a high content of β-CSi. Moreover, the optimal process parameters were selected concerning grafting rate, chemical composition, microscopic morphology, crystalline transformation, dimensional accuracy, mechanical properties, biodegradability and biocompatibility of CSi-KH571. The elastic modulus and compressive properties of CSi25-55 scaffolds exhibited a notable improvement of 29.71 % and 59.30 %, respectively, compared to CSi-50 scaffolds. By regulating the phase composition of CSi, CSi25-55 scaffolds were designed to possess a controllable degradation. In vitro cell culture experiments validated its excellent biocompatibility and promoted the proliferation and differentiation of bone marrow mesenchymal stem cells (BMSCs) as well as the deposition of bone matrix. Herein, a novel and sustainable approach has been promoted for enhancing the interfacial bonding capacity of inorganic/organic materials and the solid-phase content of printing slurry, which lays the foundation for the printing of high-resolution degradable bioceramic scaffolds.

Reactive transport of Cd2+ in porous media in the presence of xanthate: Experimental and modeling study

In mining regions, flotation reagents can interact with heavy metals, thereby increasing the complexity of their migration. However, most current studies solely focus on the migration of heavy metals, neglecting the influence of flotation reagents in their models concerning mining area pollution. This study developed the reactive transport model, Multisurface Speciation Model (MSM), which integrated the reaction processes of the three main soil components (iron oxides, organic matter, clay minerals) and ethyl xanthate (EX), a typical flotation reagent, with cadmium (Cd²⁺) to investigate the effects of EX on the transport and retention of Cd²⁺ in natural porous media under varying pH conditions. The study revealed that EX formed new adsorption sites for Cd²⁺, enhancing its retention and inhibiting transport with increased EX loading (0 to 2.5 mmol·L−1), while higher pH levels (ranging from 4 to 8) further strengthened the retention capability of Cd²⁺. The MSM further predicted the solid-phase concentration distribution of Cd²⁺ among various components. With increasing EX-loaded concentrations, xanthate became the dominant adsorbing component, accounting for 48.93 % to 95.31 % of adsorption, and competitively interacted with other components. Xanthate retention was lower under acidic conditions compared to neutral and alkaline environments. Sensitivity analysis highlighted the concentrations of iron oxide adsorption sites (SurfaOH, SurfbOH) as critical parameters in the models, underscoring the need for precise determination of soil physicochemical indicators. This study stressed the crucial role of flotation reagents and pH conditions in controlling heavy metal mobility, offering important insights for environmental management in mining regions.

Multi-component wastewater from finely dispersed impurities treatment intensification

The article deals with the intensification of flocculation wastewater treatment from finely dispersed suspended dust particles that are formed in the foundry shop at machine-building productions. The dependence of the floc sedimentation rate and wastewater clarification on solid phase concentration and flocculant flow rate was experimentally researched using model wastewater created by mixing dust and water. The multicomponent impurities of ionic flocculants on the aggregation process impact were experimentally proven, and anionic and cationic flocculants combination high efficiency was shown. The optimal parameters for the wastewater treatment process were established. The best flocculating effect and minimum flocculant consumption were observed at a solid phase concentration of 8-14 g/l. It was established that the most effective aggregate formation process is observed when two flocculants’ types are used simultaneously: anionic A-19 and cationic K-7, not each type separately. Flocculant flow rate experimental and calculated dependences for the wastewater treatment process depending on solid phase concentration and floc sedimentation speed necessary for effective sedimentation have been established. A technological scheme for wastewater treatment from suspended dust impurities that are formed in foundry shop at machine-building enterprise has been developed. The scheme includes: wastewater flocculation; water clarification in a sedimentation tank; and water deironing by aeration with coagulant addition and further filtration. It is proposed to use purified water in enterprise technological cycle that helps to reduce tap water consumption.

Study on the Flow Velocity of Safe and Energy-Saving Transportation of Light-Particle Slurry

In order to determine the recommended flow velocity for the safe and energy-saving transport of ice-slurry-type light particle slurries, it is necessary to study the flow characteristics of light particle slurries, especially the critical flow velocity. Therefore, in this paper, a numerical simulation method based on the mixed turbulence model with the RANS (Reynolds averaged Navier Stokes) equation is used, and a new concentration distribution method is proposed for the first time to derive the critical flow velocity, as follows: the flow velocity of the light particle slurry when the ratio of the solid volume fraction vf at the position of 0.08D above the bottom of the pipeline to that at the center of the pipeline, vf/vf(y) = 0.75, is taken as the critical flow velocity. The flow changes in the slurry (polyethylene particles with a density of 922 kg/m3 and water) under 0.1–1.0 m/s (at intervals of 0.1 m/s) were investigated experimentally, and the pressure drop data obtained from the experiments were used to determine the recommended flow rate for safe and energy-saving transportation of the light particle slurry. The pipe diameter used for the experiments and simulations was 28 mm, and the solid-phase particle sizes were 0.3 mm, 0.4 mm, and 0.5 mm, with solid-phase contents of 5 vol%, 10 vol%, 15 vol%, and 20 vol%. In addition, the experimental and numerical simulation results show that an increase in solid-phase content and particle size leads to an increase in critical flow velocity.

Natural convection of water-based nanofluids in three-dimensional enclosures

The single-phase approach, in which nanofluids are treated as pure fluids assuming that the solid and liquid phases are in local thermal and hydrodynamic equilibrium, has been used with good results to simulate forced convection flows. Conversely, its extension to natural convection has revealed to be more problematic, as the obtained numerical results are substantially different from the experimental data, mainly due to the effects of the slip motion occurring between the suspended nanoparticles and the base liquid, whose consequent nonuniform distribution of the solid phase concentration can significantly affect both heat and momentum transfer. In the present article, a two-phase model based on a double-diffusive approach is proposed to study the natural convection flows of water-based metal oxide nanofluids inside cylindrical and rectangular enclosures heated and cooled at their opposite sides with the scope to reproduce a number of experimental data-sets available in the literature. Given the assumption of local thermal equilibrium between nanoparticles and host liquid, and considering the Brownian and thermophoretic diffusion as responsible for causing significant relative velocity between the solid and liquid phases, the governing equations are solved by a control-volume numerical method implemented using the open-source platform OpenFOAM (Open Field Operation and Manipulation). It has been found that the nanoparticle diffusion gives the major contribution to the decrease of the heat transfer rate red usually observed experimentally in natural convection flows of nanofluids inside differentially-heated enclosures. This means that a two-phase model, in conjunction with proper correlations for the evaluation of the nanofluid effective physical properties, must be necessarily enforced to obtain reliable results for many engineering applications.

Investigation on gas–liquid–solid three-phase flow model and flow characteristics in mining riser for deep-sea gas hydrate exploitation

In response to the problem of gas–liquid–solid three-phase flow in deep-sea hydrate extraction pipelines, a gas–liquid–solid three-phase flow model considering the dynamic decomposition of hydrates is established using continuity equations, momentum equations, and energy equations. The numerical solution of the theoretical model is achieved using the finite difference method. Comparing the theoretical model with the experimental results, the results showed that the average error of gas holdup, liquid holdup, solid phase content, gas phase velocity, liquid phase velocity, and solid phase velocity obtained from the theory and experiment are 8.24%, 0.41%, 1.88%, 5.80%, 2.81%, and 2.22%, respectively, which verified the correctness of the theoretical model. On this basis, the influences of hydrate abundance, liquid phase displacement, and wellhead backpressure on the gas–liquid–solid three-phase flow characteristics in the pipeline were investigated, and it was found that the gas holdup rate will increase with the increase in hydrate abundance, liquid phase displacement, and wellhead backpressure, with the influence of hydrate abundance being more sensitive. The liquid holdup rate increases with the increase in hydrate abundance and liquid phase displacement, but decreases first and then increases toward the wellhead position with the increase in wellhead backpressure. The solid phase content decreases with the increase in hydrate abundance, and first increases and then decreases toward the wellhead position as the liquid phase displacement and wellhead backpressure increase. The influence of gas phase velocity on the abundance of hydrates is relatively small, but it increases with the increase in liquid phase displacement. When the wellhead backpressure increases, the instantaneous increase then tends to flatten out. The influence of hydrate abundance on the liquid phase velocity is also relatively small, but it increases with the increase in liquid phase displacement and decreases with the increase in wellhead backpressure. The solid phase velocity will increase with the increase in hydrate abundance and liquid phase displacement, but it will not show significant changes with the change of wellhead backpressure. The research results can provide a theoretical basis for the safety of hydrate mining.

Preparation and mechanical performance analysis of porous Ti6Al4V scaffold fabricated by direct ink writing

In order to mitigate the stress-shielding effect resulting from the stiffness disparity between titanium alloy and bone, the use of additive manufacturing to create porous Ti6Al4V components shows promise for orthopedic implant applications. In this study, a novel hot-melt–quick-frozen polyvinyl alcohol hydrogel was developed for direct ink writing to create porous titanium structures using Ti6Al4V powders with an irregular morphology. The rheological and sintering properties of inks with varying solid phase contents were examined to assess their molding quality. Furthermore, the effect of porosity on the morphology, shrinkage, and mechanical properties of the scaffolds was thoroughly investigated. The results of the experiments show that inks loaded with 65 vol. % Ti6Al4V particles exhibit the highest printing performance. Furthermore, the analysis revealed a positive correlation between the total porosity of the scaffold and its mechanical performance. In particular, the strength of the scaffold with a porosity of 54.8% exceeded that of human bone, and it also exhibited matched stiffness. Upon analyzing the final microstructure and mechanical properties, it is evident that these scaffolds meet the necessary criteria for use as orthopedic implants.

Nickel's behaviour in marine sediments under aerobic to anaerobic diagenetic conditions

In the marine environment, nickel distributions are linked to the biogeochemical cycling of both organic matter and manganese. Thus, Ni and its isotopes have the potential to be used to reconstruct changes of bioproductivity and oxygenation in paleoenvironments. However, their utility relies on an understanding of the behaviour of Ni in modern marine environments. Here we investigate the distribution of Ni under a range of oxidation-reduction conditions, with organic carbon (Corg) burial rates that range from approximately 0.08 to 8.4 mmol m−2 d−1, none of the sites show deep (> 5 cm) penetration of dissolved oxygen into the sediment. We present Ni concentrations for sediments and pore fluids, as well as Ni isotope compositions from pore fluids, from the California and Mexico continental margins. The sites are sufficiently reducing that solid-phase Mn concentrations are typically <1000 ppm, but two of the stations, where oxygenated bottom water bathes the underlying sediment, have near-surface sediment Mn concentrations that reach up to 2.3%.Dissolved Ni is lower in pore fluids for stations with high solid phase Corg compared to those stations with oxygenated bottom water and high solid phase Mn concentrations. The calculated benthic fluxes of Ni at all stations are small relative to their burial rates, which implies a high Ni burial efficiency (> 85%). Pore fluid δ60Ni values range from approximately −0.39 to +2.36 ‰, with the higher δ60Ni values occurring at the Corg-rich station, and the lower values at the Mn-rich stations. At the station with the highest Corg content, the distribution of solid-phase Ni as a function of Corg content is consistent with the strong association of Ni with Corg seen at open-ocean upwelling margins globally. In contrast, the other stations investigated here clearly do not show such an association. Our data offer support for the notion that Ni accumulation within sediments is linked to organic matter accumulation in regions of high photic zone productivity and where the sediments are reducing. However, at the sites in our study where Mn oxidation-reduction reactions occur near the sediment-water boundary, any simple relationship between Ni and Corg burial is obfuscated. With a sufficiently deep oxygen penetration depth and the formation of a solid-phase Mn oxide layer, Ni burial within the sediment can be highly efficient. Importantly, Ni is well preserved in sediments deposited under the full range of conditions studied here. This observation of high Ni preservation is an important constraint if Ni is to be used as a proxy to reconstruct paleoenvironmental conditions.

Numerical Simulation of Tailings Mortar Flowing from Dam Break by Variable Concentration Two-phase Flow Algorithm

A dam break accident of tailings pond may result in serious loss of the residents' lives and property, and usually leads to surrounding environmental disaster. Accurately calculating the flowing distance and inundation range of discharged tailings is important but remains to be solved. The main feature of tailings mortar movement is that solid particles continue to sink and accumulate during the flow process, which makes the solid concentration in the mortar constantly change, thus altering the rheological properties of the mortar. Therefore, the advancement of tailings mortar is a kind of two-phase unsteady flow with variable solid-phase concentration. In conventional numerical calculations of tailings flow, the rheological parameters of the Bingham model used are given fixed values with no consideration of concentration change, resulting in inaccurate calculation results and difficulty reflecting the phenomenon of tailings sands accumulation along the way. In this paper, a variable concentration two-phase flow model is proposed and then applied to a typical tailings dam failure case. The flow features and inundation range of the tailings mortar are analyzed and are found to be basically consistent with the field investigation, which means the proposed two-phase flow algorithm is reasonable and reliable.

Investigation of Viscoelastic-Plastic Properties of Fresh Cemented Gangue Fly Ash Backfill Slurries

In underground filling mining, freshly prepared cemented gangue-fly ash backfill (CGFB) slurries are typically piped into the gobs. The rheological properties of backfill slurry during pipeline transportation have a direct impact on the transportation characteristics, which in turn affect pipeline blockage and wear. In this paper, the rheological behavior and viscoelastic-plastic properties of CGFB during pipeline transportation are investigated. The effects of different solid content and cement content on resistivity were tested experimentally, and their viscoelasticity and plasticity were analyzed. The results show that with the increase in solid phase content and cement content, the viscosity, yield stress, and energy storage modulus of the materials showed an increasing trend. The viscosity and yield stress of the material both increased, reaching 32.77% and 51.22%, respectively. It was found by the dynamic shear test that in the low-strain region, the material showed a more significant elastic nature of the solid, while in the high-strain region, the viscosity of the material gradually increased. Cement has a substantially lower resistivity than fly ash and gangue, and with the increase in solid concentration, the resistivity of the material shows an increasing trend. With the increase in cement content, the resistivity generally shows a decreasing trend, but it should be noted that the resistivity change trend may tend to stabilize after the cement content exceeds 12%. The study’s findings can aid in understanding the rheological properties of CGFB and its viscoelastic-plastic behavior during the underground filling and conveying process, which can provide a reference basis for research and application in related fields.

Determination of antibiotics of the tetracycline group in water by high-performance liquid chromatography on a diode matrix detector with preliminary concentration by solid-phase extraction

Introduction. Antibiotic contamination of the environment is a serious environmental threat that poses a hazard to human health. To monitor the content of tetracycline antibiotics in environmental objects and control technological processes aimed at their disposal, accessible analytical methods are needed. &#x0D; Purpose of the study. Development of a method for determining antibiotics of the tetracycline group in water using a diode array detector with preliminary solid-phase concentration.&#x0D; Material and methods. The objects of the study were model solutions of minocycline, tetracycline, oxytetracycline, demeclocycline, metacycline, and doxycycline in deionized, tap, natural, and treated wastewater. For solid-phase extraction, Diapak P and Diapak PG cartridges were used. SPE was performed using a VacMaster-10 manifold (Biotage). Chromatographic separation was carried out on Diasphere C10CN and Kromasil Eternity 250 × 4.6 mm 5 µm columns on an Agilent 1100 liquid chromatograph (Agilent Technology).&#x0D; Results. Optimal conditions for the chromatographic separation of minocycline, tetracycline, oxytetracycline, demeclocycline, metacycline, and doxycycline were selected: isocratic mode, wavelength of 350 nm, mobile phase – acetonitrile: aqueous solution of phosphoric acid (pH = 3.0). The analysis time on Diasphere C10CN and Kromasil Eternity columns was 12 and 14 minutes, respectively. The reliability of the linear approximation in both cases was more than 0.99, however, the slopes on the Kromasil Eternity column were 1.35 –1.65 times higher than on Diasphere C10CN. The degree of extraction of tetracyclines from deionized water on Diapak P and Diapak PG cartridges was 90–95%, from tap water 61–89%, from purified waste water: 51–87%.&#x0D; Limitations. The method is not suitable for water bodies with tetracycline contents less than 2 µg/dm3.&#x0D; Conclusion. An HPLC method has been developed for the determination of minocycline, tetracycline, oxytetracycline, demeclocycline, metacycline, and doxycycline in water with preliminary SPE concentration on Diapak P and Diapak PG cartridges. The lower limit of determination for the sorption of target compounds from 0,1 dm3 of sample was 2 μg/dm3.

Adopting green absorbent for CO2 capture and agricultural utilization: Biogas slurry and biomass ash case

Previously, the once-through CO2 chemical absorption process by biogas slurry was experimentally verified to offer the unique advantages like low energy consumption, cost-effectiveness, and feasibility of CO2 fixation in plants. However, this technology also faces some challenges and limitations, including a low CO2 absorption rate and performance. To improve the effectiveness and reliability of this innovative carbon capture, utilization, and storage (CCUS) technology, this study proposes a novel method to enhance the CO2 absorption performance without affecting agricultural applications of CO2 by mixing biogas slurry with biomass ash as the green CO2 absorbent. The results indicate that when the solid-liquid mass ratio of biomass ash to biogas slurry is 5:10, the CO2 loading of the biomass ash and biogas slurry mixture (BA-BS) reaches 936.7 ± 59.1 mmol/kg. Furthermore, the pH of the BA-BS remains stable at 6.9, meeting the rhizosphere pH requirements for plant cultivation. The CO2 absorption of the BA-BS liquid phase, referred to as improved biogas slurry (IBS), reaches its maximum at 230.4 ± 3.5 mmol/L, which is 126.8% higher than that of the unimproved biogas slurry. The nitrogen content in the BA-BS solid phase, calling improved biomass ash (IBA), also reaches its maximum at 4.24 ± 0.74 mg/g, thereby expanding the agricultural utilization of biomass ash. The most reasonable and effective way of utilizing CO2-rich mixed biogas slurry and biomass ash involves use IBA as the base fertilizer for tomato cultivation, supplemented later with IBS to promote growth. This optimal application allows for substantial utilization of CO2, introduced into the tomato cultivation environment by IBA and IBS. The carbon fixation of a single tomato has improved by 108.2%. This study thus provides a feasible solution for high-value negative carbonization of biogas slurry and biomass ash.

Integrated optimization design of multiphase pump based on adaptive sparse grid method

Multiphase pump play a critical role in natural gas hydrate extraction. However, their stable and efficient operation in complex multiphase flow conditions remains a significant challenge. This study focuses on a “gas-liquid-solid” multiphase mixing pump and uses numerical simulations to analyze its single-stage pressure boosting unit under different conditions. The results revealed a significant decrease in pressure increment and efficiency under high gas content and solid phase content conditions. To address this, the study built an integrated optimization design platform based on an adaptive sparse grid surrogate model. This platform optimized critical hydraulic parameters of the pump through an adaptive sparse grid method and MOGA algorithm. The results show that under water conditions, pressure increment and efficiency can be increased by 12.805 KPa and 1.79%, respectively. Under working conditions of 30% GVF and 25% SVF, the pressure increment can reach 7.889 KPa, and the efficiency can be increased by 2.75%. Verification experiments demonstrated the reliability of the numerical methods utilized. Overall, the integrated optimization design platform saves computational resources, improves optimization efficiency and provides a foundation for ongoing research on the multi-gas co-production of natural gas hydrates.

Construction and Evaluation of a Degradable Drilling Fluid for Underground Coalbed Methane Extraction Boreholes.

Gas drainage with bedding boreholes is an efficient method for preventing gas and achieving coal and gas comining in underground mining engineering. An underground pressurized drilling method is proposed to maintain the borehole stability. However, the presence of natural fractures in coal seams poses challenges during pressurized drilling. Therefore, it is crucial to establish a low-leadage degradable drilling fluid system that minimizes coal seam damage. In this study, a degradable drilling fluid system was developed based on the characteristics of coal seams. The performance and influencing factors of the drilling fluid and the degrading capability of cellulase were examined. Moreover, the damage of the drilling fluid on fractured coal seams was investigated using core flow test methods. The results showed that additives significantly improved the rheology, filtration, and inhibition of the drilling fluid. The drilling fluid system exhibited excellent stability, rheological properties, low filtration, and sealing performance in coal seam environments. However, drilling fluid invasion and mud cake blockage negatively affected gas flow in fractured coal seams, and a higher content of filtrate reducer hindered the recovery of the gas flow rate. Cellulase was used to degrade polymers and alleviate the challenge of mud cake removal after drilling. Research on the influencing factors of cellulase indicates that the degradation efficiency of cellulase enzymes is influenced by the temperature, pH, salinity, and solid-phase content. For polluted coal samples, the gas flow rate significantly recovered after treatment with a cellulase solution. This study provides insights into a degradable drilling fluid system that can enhance underground pressurized drilling methods and minimize reservoir damage.