Initial Solution Concentration Research Articles

Dynamic Trio: CuWO4@C3N5/Polypyrrole Nanocomposites Combat Chlorpyrifos and Rhodamine B in Waste water

In this study, we investigate the photocatalytic degradation of chlorpyrifos pesticide (CPy) and Rh B dye using nanoparticles of C3N5 and CuWO4 dispersed within a PPy matrix. Using a variety of techniques, a composite called PPy@C3N5/CuWO4 was synthesised and thoroughly characterised. These techniques included XRD, SEM/EDS, TEM, BET, DRS, PL, and TOC. The combination displayed remarkable photoactivity and photostability in the degradation of CPy and RhB in aqueous solutions when exposed to visible light. The band gap values of C3N5, CuWO4, and C3N5@CuWO4 are (2.2, 2.0, and 1.9 eV), improved. Several factors were meticulously optimised and adjusted in order to investigate the process of photocatalytic degradation. These factors included pH levels, initial solution concentration, irradiation time, and the amount of photocatalyst used. An optimal photodegradation efficiency of approximately 92.5% was attained by utilising a CPy and Rh B concentration of 5 mg/L, maintaining a pH of 3.5, and employing a photocatalyst dosage of 0.5 g/L. The photocatalyst was also tested for its ability to regenerate and be recycled four times, which showed that it was relatively stable.

A simple model of the soil freezing characteristic curve for saline soils with two freezing stages

Soil freezing characteristic curve (SFCC) describes the relationship between unfrozen water and subzero temperature, which is of significance for the simulation of heat, water, salt migration in cold regions. There are two phase transition stages in some saline soils, which is often explained by the phase equilibrium of bulk solution. However, the second phase transition and chemical characteristic of solute are ignored in the current coupling numerical models for freezing-thawing soils. The newest SFCC methods considering abovementioned two items are not applicable to numerical models due to complex calculation or irregularly changeable parameters. To solve those problems, a simple model was proposed in this paper. Firstly, the complete phase diagram of pore solution at icing stage was speculated from published experimental SFCCs of saline soils. Then, the temperatures of saline soils at freezing and eutectic points were quantitative expressed with phase diagram of bulk solution and SFCC of nonsaline soil, and the criteria determining whether single icing stage or icing-eutectic stage occurs in saline soils was proposed. A synthetic index was used to describe the effects of soil matrix and initial solute concentration on the exponent. Only three constant parameters were introduced to reflect the soil matrix effect on phase transition points of pore solution and the influence of chemical characteristic of solute on pore water freezing process. Finally, the model was validated by the experimental data of saline soils and showed good results and ease of use compared to a widely used theorical model for saline soil with single freezing stage and other two models both considering two phase transitions. The work provides a deeper view of freezing process in saline soils and promote the improvement of numerical simulation effect for heat, water and salt migration in seasonal freezing-thawing areas.

Adsorption of Chromium (III) and Chromium (VI) Ions from Aqueous Solution Using Chitosan-Clay Composite Materials.

In this work, biopolymer chitosan and natural clay were used to obtain composite materials. The overall aim of this study was to improve the properties (porosity, thermal stability and density) of pure chitosan beads by the addition of clay and to obtain a chitosan-based composite material for the adsorption of heavy metals from an aqueous solution, using Mongolian resources, and to study the adsorption mechanism. The natural clay was pre-treated with acid and heat to remove the impurities. The chitosan and pre-treated clay were mixed in different ratios (8:1, 8:2 and 8:3) for chemical processing to obtain a composite bead for the adsorption of chromium ions. The adsorption of Cr(III) and Cr(VI) was studied as a function of the solution pH, time, temperature, initial concentration of the chromium solution and mass of the composite bead. It was found that the composite bead obtained from the mixture of chitosan and treated clay with a mass ratio of 8:1 and 8:2 had the highest adsorption capacity (23.5 and 17.31 mg·g-1) for Cr(III) and Cr(VI), respectively, in the optimum conditions. The properties of the composite materials, prepared by mixing chitosan and clay with a ratio of 8:1 and 8:2, were investigated using XRD, SEM-EDS, BET and TG analysis. The adsorption mechanism was discussed based on the XPS analysis results. It was confirmed that the chromium ions were adsorbed in their original form, such as Cr(III) and Cr(VI), without undergoing oxidation or reduction reactions. Furthermore, Cr(III) and Cr(VI) were associated with the hydroxyl and amino groups of the composite beads during adsorption. The kinetic, thermodynamic and isothermal analysis of the adsorption process revealed that the interaction between the chitosan/clay composite bead and Cr(III) and Cr(VI) ions can be considered as a second-order endothermic reaction, as such the adsorption can be assessed using the Langmuir isotherm model. It was concluded that the composite bead could be used as an adsorbent for the removal of chromium ions.

Enhanced Nitrate Nitrogen Removal from Wastewater Using Modified Reed Straw: Adsorption Performance and Resource Utilization

This paper presents a study on the efficient removal of nitrate nitrogen from wastewater using modified reed straw (MRS) and its subsequent resource utilization. The modification of the reed straw involved the introduction of branching quaternary amine groups to enhance its adsorption capacity for nitrate nitrogen. Experimental investigations were conducted to analyze the impact of packing height, flow rate, and initial solution concentration on the dynamic adsorption performance of the MRS. The results revealed that the maximum dynamic adsorption capacity of the MRS for nitrate nitrogen reached 14.76 mg/g. Furthermore, valuable nitrate nitrogen nutrient solution was successfully recovered through subsequent desorption experiments for resource recycling. Moreover, the application of the MRS led to notable enhancements in column height, fresh weight, chlorophyll content, and nitrogen content of the treated plants, indicating its efficacy in promoting plant growth. Overall, the findings demonstrate that MRS serves as a versatile adsorbent capable of efficient nitrate nitrogen removal and subsequent resource utilization.

Synthesis of ZnO and ZnO/Ag fine particles by plasma-assisted inkjet processing

Zinc oxide (ZnO) and its composite particles with controlled sizes, shapes, compositions, and physical and chemical properties are required for a wide variety of applications. In this study, we report a simple method for synthesising ZnO and ZnO/Ag composite particles via atmospheric-pressure plasma processing using inkjet droplets. Depending on the initial solution concentration, ZnO particles containing voids, with average sizes ranging from submicrons to several microns can be synthesised. Energy dispersive x-ray spectroscopy measurements of the synthesised ZnO/Ag particles suggest that the molar ratio of Ag to Zn in the initial solution was retained in the synthesised particles. A high surface-enhanced Raman scattering effect was observed in the particles synthesised from the solution with an Ag molar ratio of 50% to the total solute. The proposed method enables the synthesis of ZnO particles of various sizes, microstructures, compositions and optical properties with relatively narrow size distributions.

Magnetic zinc oxide/silica microbeads for the photocatalytic degradation of azo dyes

Photocatalysis is a promising technique for the complete degradation of azo dyes that are present in wastewater. In this work, a new photocatalyst in the form of ZnO/Fe3O4/SiO2 hybrid microbeads was fabricated for the photocatalytic degradation of methylene blue. The microbeads were synthesised through self-assembly and subsequent agglomeration of nanoparticles within an aqueous phase of a water-in-oil emulsion template. Photocatalytic degradation experiments were conducted through exposure of a methylene blue solution to UV light. The hybrid microbeads performed better than ZnO powder at the same initial dye and ZnO concentration because of higher adsorption and degradation. The initial concentration of dye solution and catalyst dosage have a significant impact on the degradation. Higher degradation is seen with lower initial dye concentration and higher catalyst dosage. The presence of magnetic nanoparticles within the beads allows for their full recovery and reuse for degradation experiments. Complete degradation of dye was achieved using the new ZnO/Fe3O4/SiO2 microbeads.

Enhancing Cr (VI) Adsorption of Chestnut Shell Biochar through H3PO4 Activation and Nickel Doping.

A high-efficiency nickel-doped porous biochar (PCNi3) has been successfully synthesized from chestnut shell waste via a two-step chemical activation treatment with H3PO4. The influences of microstructure, surface morphology, elemental composition, surface functional groups, specific surface area, porosity, pore-size distribution, and chemical properties of the surface state on the removal of Cr (VI) from water were thoroughly investigated by using XRD, FESEM, FTIR, Raman, BET, and XPS testing methods, N2 adsorption, and XPS testing techniques respectively. The results indicate that the treatment of H3PO4 activation and nickel doping can effectively improve microstructure characteristics, thus promoting Cr (VI) adsorption capacity. The effects of initial solution pH, solution concentration, time, and temperature on remediation are revealed. The Cr (VI) uptake experiments imply that the adsorption curves of PCNi3 fit well with the Freundlich model, the pseudo-second-order kinetic model, and the Elovich model. The adsorption process of PCNi3 can be regarded as a spontaneous endothermic reaction limited by diffusion among particles and porosity. The adsorption mechanisms of PCNi3 are ion exchange, complexation, electrostatic adsorption, and coprecipitation with the assistance of surface active sites, porosity, Ni0 particles, and Ni7P3. With these advantages, PCNi3 reveals an extraordinary Cr (VI) removal capacity and a strong ability to reduce Cr (VI) to Cr (III).

Separation of V(Ⅴ) and Cr(Ⅵ) from vanadium-containing solutions based on E-pH diagrams of V-Cr-S-H2O system

The extremely similar physicochemical properties of vanadium and chromium lead to the difficulty in separating from each other. In this study, a novel hydrometallurgical process was devised to selectively precipitate chromium from vanadium-containing solutions, facilitating the efficient separation of V(V) and Cr(VI) while enabling the recovery of both vanadium and chromium species. The speciation of vanadium and chromium in solutions was investigated through the construction of E-pH diagrams for V-Cr-S-H2O system at 298 K, 363 K, and 453 K. The results revealed that under conditions of pH approximately 12 and temperature 363 K, the reduction potential of SO42-/S2- was found to lie between that of CrO42-/Cr(OH)3 and VO43-/V2O3. This suggests that selective reduction of Cr(VI) could be achieved using S2- as reducing agent. In order to validate the theoretical findings, single-factor experiments were conducted on a laboratory scale. The effects of various parameters including initial pH, sodium sulfide dosage, reaction time, temperature, and initial concentration of vanadium-containing solutions on the chromium precipitation ratio and vanadium loss ratio were investigated. The experimental outcomes showed that the chromium precipitation ratio reached 99.8 % while the vanadium loss rate was only 3.5 % when the experiment was conducted at the optimal conditions: the initial pH was set to 12, sodium sulfide dosage was 2.0 times of the theoretical dosage, reaction time was 60 min and the temperature was 363 K. Then, the chromium concentration in the solution decreased from 2407 mg/L to 3.3 mg/L. Ultimately, V2O5 with a purity of 99.0 % and Cr2O3 with a purity of 97.2 % were successfully obtained.

Advancing solar-powered hybrid FO-MD desalination: Integrating PVT collectors and PCM for sustainable water production in residential building

The global focus on water desalination using solar energy is particularly pronounced today. Previous studies have affirmed the efficiency of the Forward Osmosis (FO) and Membrane Distillation (MD) hybrid desalination system. The Photovoltaic Thermal (PVT) solar system, which generates both thermal and electrical energy, is complemented using Phase Change Material (PCM). PCM, known for storing and releasing significant heat during phase change, is used in the evening to meet the thermal needs of the system. Additionally, an integrated battery system stores the electrical energy generated by PVT, ensuring the system's electricity requirements are sustained during the night. A comprehensive numerical model, PVT-PCM-FO-MD, has been developed to analyze the proposed system. Operating seamlessly under natural conditions for a typical day on March, June and September, the proposed system can produce freshwater continuously over a 24-hour period. To assess system performance, three PCM thicknesses (2 cm, 4 cm, and 6 cm) were employed. Designed for small-scale applications, this system is well-suited for brackish water desalination in remote areas. Notably, the highest water production recorded was 213.25 L during a 24-hour operation and the MD unit exhibited an impressive 83.78 % evaporation efficiency during the typical day on June, with nighttime efficiency reaching 37.07 %, specifically at 3 am, utilizing a 2 cm PCM thickness in the solar energy system and it was 37.22 % at the same hour and PCM thickness in September. This study further explores the impact of initial brackish water salinity on water production after 24 h and investigates the influence of the initial draw solution concentration in the draw tank on desalinated water production. The study found that despite varying initial salinity levels, the difference in water produced at the end of the day was not exceeding 1.6 L.

Enhanced heavy metal adsorption capacity of surface-functionalized Philippine natural zeolite in simulated wastewater

The adsorption efficiency of surface-functionalized Philippine natural zeolite (PNZ) for heavy metal uptake from single and mixed metal ion-simulated wastewater solution is reported in this work. Atomic adsorption spectroscopy (AAS) findings revealed that NaCl-modified PNZ (MPNZ) exhibited the highest zinc ion adsorption of 99.96 % while PNZ yielded an adsorption of 95.61 %. The adsorption isotherms of raw PNZ and MPNZ both show similar shapes that reflect Type IV adsorption-desorption isotherms with Type H2 hysteresis loop which can be observed for micro-mesoporous materials (pore containing 2–50 nm). An increase in PNZ pore size from 10.11 nm to 13.36 nm for NaCl-PNZ and 15.59 for NaOH-PNZ is observed after alkaline treatment. EDS confirmed the decrease in Si/Al ratio from 4.02 to 3.76, indicative of possible higher negative charge in the PNZ framework which is favorable for an enhanced Coulombic or electrostatic interaction with the cationic heavy metals being detected in this study. MPNZ demonstrated an adsorption capacity of 99.96 % for copper in mixed-ion solution while 88.49 % and 86.67 % were obtained for zinc and nickel, respectively. These values are higher compared to PNZ having only 32.21 % uptake for zinc and 38.00 % for nickel. A hierarchy of the average metal adsorption capacity showed the order: copper > nickel > zinc. Rapid adsorption at the first hour of the adsorption reaction was attained in all solutions while samples with pH 9 exhibited the highest Ni2+ and Zn2+ percent removal. Moreover, the increase in initial solution concentration led to lower adsorption efficiency and the maximum uptake was attained at 100 ppm. The equilibrium data of adsorption and mechanism were suitably described by Langmuir isotherm model. With these, surface functionalization of PNZ has further enhanced its cationic adsorption capacity on heavy metals in both single and mixed-ion solution having promising potential for wastewater remediation.

Study on Properties of Micro-Nano Magnetic Composite Prepared by Mechanochemical Method of NdFeB Secondary Waste and Removal of As (V) from Mine Water

The secondary waste produced by NdFeB waste after rare earth recycling, with an annual output of more than tens of thousands of tons, is the largest solid waste emission source in the rare earth industry, and long-term storage causes land resource occupation and environmental pollution. Arsenic-containing mine wastewater has serious harm, wide distribution, and long duration of pollution. In this study, the mechanical ball milling method was used to activate NdFeB secondary waste to prepare micro-nano magnetic composite materials, the main components of which are Fe2O3, Fe3O4, and C. Under mechanical mechanochemical action, the particles are more dispersed, the particle size decreases, the specific surface area increases significantly, the crystal structure changes to amorphous structure, the degree of amorphous shape increases, and the content of Fe-OH increases. Applied to the treatment of As (V) in simulated mine water, it was found that the removal of As (V) by this material was mainly based on chemisorption and monolayer adsorption, and the maximum adsorption amount reached 10.477 mg/g. Zeta, FT-IT, and XPS characterization confirmed that the removal of As (V) was a coordination exchange reaction between the material and As (V) to form an inner sphere complex. The removal rate of As (V) decreased from 94.33% to 73.56% when the initial concentration of solution was 10 mg/L, pH value was 3.0, and material dosage was 1 g/L after 5 times of regrowth. This study provides a new way for the application of NdFeB secondary waste, which has low cost, green environmental protection, and wide application prospects.

Preparation of a Porous Protein-Based Composite Material by In Situ Polymerization of Pickering High Internal Phase Emulsion for Adsorption of Lead Ions.

The preparation of complex porous materials using a small molecular surfactant as the stabilizer of a high internal phase emulsion can result in harm to the environment. In this study, porous composites based on soy protein isolate with poly(acrylic acid) were prepared by in situ polymerization of a high internal phase monomer emulsion with an internal phase volume fraction of 80%. The material was prepared from acrylic acid and an N,N-methyl diacrylic acid monomer solution as the continuous phase, peanut oil as the dispersed phase, and soy protein isolate as the composite stabilizer. Scanning electron microscopy showed that porous composites exhibited a concave/convex three-dimensional interpenetrating pore structure. Fourier-transform infrared spectra revealed the existence of many active groups such as carboxyl, amino, hydroxyl, and sulfhydryl. The composite had a high adsorption capacity for lead ions, even at low concentration, with a removal rate of up to 95.7%. The adsorption process conformed to a two-stage model involving internal diffusion and Langmuir isothermal adsorption. The maximum saturated adsorption capacity was 36.71 mg/g when the initial solution concentration was 150 mg/L, the adsorbent concentration was 7.0 g/L, and the adsorption mechanism involved chemical interactions between the lead ions and the composite groups -COOH, -OH, and -SH.

Response of Sandy Soil–Water Migration to Different Conditions under Unidirectional Freezing

In order to conserve valuable soil and water resources and avoid problems related to frozen soil, it is important to study the migration of frozen soil water. A greater understanding of frozen soil–water migration can assist with sustainable development and utilization of soil and water resources in frozen areas. This study used an indoor soil column test device to conduct a one-way indoor freezing test of unsaturated soil and the response of soil sample water migration to different freezing temperatures, initial moisture contents, soil densities, freezing times, solute concentrations, and solute types. The experimental and analytical results showed that the temperature field of the soil sample could be divided into three stages: sharp cooling, slow cooling, and stability. After the soil sample had been frozen for 100 h, the temperature field stabilized. The freezing temperature, initial water content, soil density, and freezing time affected water migration in the soil sample. Lower freezing temperatures and greater initial water content resulted in higher levels of water migration. By contrast, greater soil density led to lower water migration levels. In addition, longer freezing times produced smoother soil–water migration curves. The solute concentration and solute type also affected water migration in frozen soil; the higher the solute concentration, the greater the water migration. Compared with CaCl2, NaCl had a stronger effect, causing more water migration and leading to a higher water content. The research findings will aid further studies on soil and water utilization, environmental maintenance, and restoration in areas with seasonally frozen soil, as well as promote the sustainable development of agriculture, water conservancy project development, and the social economy.

The absorption effect and mechanism of graphene oxide removal from aqueous solution by basalt stone power

Graphene oxide (GO) is a novel carbon material utilized extensively for diverse industrial applications. When exposed to environmental elements like sunlight and chlorination, GO can undergo a series of physical and chemical transformations, and its presence in water and the environment can endanger ecosystems. Therefore there is a need for methods that can effectively remove GO from water. Accordingly, we delve into the efficacy of basalt stone powder (BSP) as an adsorption medium for purifying aqueous solutions of GO. We examine the impact of various experimental parameters—namely pH, initial solution concentration, adsorbent mass, contact duration, and ambient temperature—on GO adsorption, employing the method of controlled variables. The adsorption efficacy is notably influenced by the pH level. At an acidic pH of 3, an initial GO concentration of 80 mg/L, an adsorbent dosage of 50 mg, and a temperature of 303 K (approximately 30 °C), the adsorption removal efficiency reaches an impressive 99 %, boasting a maximum adsorption capacity of 112 mg/g. Dynamically, the adsorption kinetics align most closely with a pseudo-first-order model, achieving equilibrium after 24 h. Thermodynamic analyses reveal that the Langmuir isotherm model most accurately describes the adsorption behavior, indicating an enhancement in BSP's adsorption capacity for GO as temperature rises. Based on thermodynamic equations, the adsorption of GO onto BSP is deduced to be a spontaneous process. Our findings illustrate BSP's considerable potential in the treatment and removal of GO from water, and therefore it may prove useful in environmental remediation efforts.

Power-efficient mass transfer of a novel pulsating multi-packed bed liquid - liquid extractor

This paper presents the development and performance evaluation of a new pulsating packed bed contactor designed for optimized diffusion-controlled liquid-liquid operations. Targeting applications like aromatics separation in petroleum, phenol removal from wastewater, and heat-sensitive material extraction (e.g., antibiotics), the contactor offers substantial advantages over traditional mechanical systems – notably, lower power consumption for equivalent production rates. Using the widely studied extraction of acetic acid from toluene-acetic acid by water as a model system, this work comprehensively investigates the factors impacting mass transfer within the pulsating contactor. Key variables explored include physical properties of the feed solution, oscillation frequency and amplitude, initial concentration of solute, flow rates, bed height, packing diameter, and bed spacing. Results reveal a significant enhancement in mass transfer with increasing frequency, amplitude, initial concentration, continuous phase flow rate, and dispersed phase flow rate. Interestingly, while increasing bed height initially improves mass transfer up to a specific point, further height increase exhibits a diminishing return. Packing sphere diameter shows minimal impact, while bed spacing has a negligible effect. A novel dimensionless equation effectively correlates the pulsating multi-packed bed data for broader applicability. To assess economic viability, the study also measures the mechanical power consumption under various operating conditions. Finally, diverse potential applications across pharmaceuticals, chemicals, biochemicals, petroleum, and nuclear fuel reprocessing are highlighted, showcasing the broad utility of this innovative mass transfer technology.

Influence of the solvent removal method on the morphology of polystyrene porous structures prepared via thermally induced phase separation

AbstractThermally induced phase separation (TIPS) allows preparation of nano and micro-porous structured materials for various applications. The literature thoroughly examines the impact of initial polymer solution concentration and cooling rate on the products morphology. On the contrary, the influence of the solvent removal methods was so far researched scarcely. Hence, we compare both qualitatively and quantitatively the effects of the solvent removal method on pore size distribution, structure, porosity, and thermal conductivity. Our study was carried out with samples prepared by TIPS from polystyrene/cyclohexane solutions employing either extraction agent or lyophilization at different solvent removal temperatures. Materials exhibited interconnected pore structure, implying good sound insulation properties, and had low thermal conductivity, offering the combination of thermal and sound insulation in one layer of material. Pore sizes after lyophilization were up to two times larger than after solvent removal by an extraction agent. On the other hand, the use of extraction agent led up to 10% porosity decrease with average porosity after lyophilization being above 82%. Our findings demonstrate that the solvent removal method is an important parameter during TIPS and that pros and cons of both methods should be carefully considered to obtain optimal material and TIPS process economy.

Treatment of simulated brominated butyl rubber wastewater using monovalent anion perm-selective membranes through selective electrodialysis

Selective electrodialysis (SED) technology utilizing monovalent anion perm-selective membranes (MAPMs) has potential in resource recovery and wastewater treatment. However, the development and production of homogeneous MAPMs with high performance and scalability pose significant challenges. This study successfully scaling up a poly(alkyl-biphenyl pyridinium)-based MAPM suitable for large-scale SED applications and applies it to the treatment of mono-/di-valent anion wastewater. The pilot-scale membrane exhibits significantly higher perm-selectivity for various mixed anion systems compared to the commercial ACS membrane, and under the conditions of a current density of 40 mA cm−2, an initial dilute chamber solution of 3 L 0.5 mol/L NaCl, and a constant concentration chamber volume of 0.2 L, the pilot-scale membrane achieves a salt (NaCl) concentration of 18.6 wt% in just 70 mins in the membrane stack, with an energy consumption of 0.38 kWh kg−1. Furthermore, simulated brominated butyl rubber wastewater is treated with the aim of refining NaBr and separating SO42- ions. Several factors, such as applied voltage, initial concentration of the dilute chamber solution, feed flow rate, and dilute-to-concentrated chamber volume ratio are investigated to assess their effects on the treatment results. By continuously optimizing the operating conditions, a NaBr product with a concentration ratio of 6.2 and a purity of 97.8 % was obtained, with the Br- ion flux of 3.24 mol m-2 h−1 and an energy consumption of 0.319 kWh kg−1.

CHEMICALLY CROSSLINKED CELLULOSE-BASED HYDROGEL PREPARED FROM RICE STRAW FOR THE REMOVAL OF AQUEOUS HEXAVALENT CHROMIUM ION FROM WASTEWATER

Then, this purified cellulose was co-polymerized by the addition of acrylic acid and ammonium persulfate in the presence of N,N-methylenebisacrylamide as crosslinker to form a cellulose-based hydrogel for the removal of hexavalent chromium (Cr(VI)) from wastewater. Here, the impact of various parameters, such as pH, contact time, material dosage, and initial solution concentration, on the adsorption capacity of the hydrogel for Cr(VI) ions is systematically investigated. The experimental findings revealed that the highest adsorption capacity for the treatment of Cr(VI)-containing water reached 1.1 mg Cr(VI)/g at pH 1, contact time of 120 min, and the initial concentration in the aqueous solution of 10 mg/L for an applied adsorbent dosage of 0.2 g. In addition, the equilibrium adsorption data agreed well with the Langmuir isotherm and the maximum adsorption amount was 4.14 mg Cr(VI)/g. Additionally, this material demonstrated good reusability, supporting the notion that it can be efficiently regenerated for multiple uses, a crucial factor for its practical application towards reducing the environmental impact and increasing its economic value.

Study on removal performance of Fe3+ by biomass-based activated carbon and Liquefaction of Poplar Sawdust catalyzed by ferro activated Carbon

The adsorption experiment of iron ions on biomass based nut shell activated carbon was conducted to explore the adsorption capacity of iron ions on biomass based activated carbon and the key influencing factors: pH value, initial concentration of solution and adsorption time on the adsorption effect of activated carbon. The preparation of supported catalyst of activated carbon iron and its influence on the effect of catalytic liquefaction of poplar sawdust were investigated. The results showed that the optimal pH value of Fe3+ solution adsorbed by activated carbon was 5.0. The adsorption rate of activated carbon decreased with the increase of initial ion concentration, and the adsorption equilibrium of activated carbon reached at 250min. The optimum concentration of poplar sawdust liquefaction catalyzed by iron supported on activated carbon is between 6mg/L and 10mg/L.

A data-driven model for a liquid desiccant regenerator equipped with an evacuated tube solar collector: Random forest regression, support vector regression and artificial neural network

The application of a solar-assisted liquid desiccant air-conditioning system equipped with evacuated tubes, focusing on the assessment and comparison of various artificial intelligence (AI) models is investigated. Specifically, Support Vector Regression (SVR), Multi-Layer Perceptron Artificial Neural Network (MLP-ANN), and Random Forest Regression (RFR) models are assessed for predicting key performance indicators: mass removal rate, efficiency, and effectiveness. Additionally, different optimizers within the Artificial Neural Network (ANN) framework—such as Adam, Stochastic Gradient Descent (SGD), and RMSprop—are systematically examined and tuned. The study encompasses the selection of the most suitable AI model for each target variable, considering parameters such as ambient temperature, solar radiation, timestamp, airflow rate, and initial solution concentration as influential factors in the modeling process. It is found that the best predictor model for effectiveness is SVR with RBF kernel. For MRR and efficiency, it is MLP-ANN with respectively AdamW and NAdam optimizers. The disparity of prediction of the MRR, efficiency and effectiveness target are respectively 0.72%, 1.07% and 0.5%, on average, indicating a precise prediction. Furthermore, including timestamps as model inputs significantly boosts accuracy, an aspect often neglected in prior research, leading to a noticeable minimum 5% rise in the R2 score.