Composite Spheres Research Articles

A renewable biological adsorbent fabricated Trichoderma viride composite spheres filled with spent Phellinus igniarius substrate exhibiting effective decontamination phosphate from water at wide range pH

Effectively recovering local waste and utilizing it as adsorbents to absorb phosphate is crucial for resource utilization and mitigating water eutrophication. In this study, we successfully prepared SPS-Trichoderma viride spheres adsorbent (SPS-T.viride) using spent Phellinus igniarius substrate (SPS) at 25 °C and pH = 6. The maximum surface area of SPS (185.22 m2/g) SPS-T.viride obtained the highest P adsorption (126.65 mg P/g) at a dosing ratio of 30 g/L, which was 4–9 times higher than the adsorption capacity of other mycobacterial materials, which was caused by synergistic interactions between chemical and physical processes in the adsorption mechanism of phosphates. Remarkably, SPS-T.viride composite spheres demonstrate notable adsorption efficiency across diverse pollutants, particularly showing selective affinity for anionic pollutants. The practical applicability of SPS-T.viride composite spheres was assessed using real sewage samples, achieving an impressive removal rate of over 80 % under dynamic flow conditions. This approach highlights the potential of biosorbents in addressing environmental challenges while achieving sustainability and renewability.

Removal of Humic Acid from Water by Adsorption Using Chitosan and Metal Organic Framework ZIF 8 Loaded Chitosan Adsorbents

Water is the most necessary need for life on the earth. There are a lot of organic pollutants in water. One of the organic pollutants is natural organic substances. Humic acid, a natural organic substance, turns into very harmful substances along with other pollutants. In this study, the humic acid removal from aqueous solution by adsorption using chitosan and chitosan/ZIF 8 composite spheres was examined. Chitosan spheres cross-linked with epichlorohydrin (ECH) and composite spheres consisting of metal organic framework ZIF8 and chitosan were prepared as adsorbents. Equilibrium, kinetic, and thermodynamic studies were investigated for humic acid adsorption by pristine chitosan-ECH and composite chitosan/ZIF 8 adsorbents. Chemical adsorption was found to be compatible with the Freundlich isotherm model and the pseudo-first-order kinetic model for pure chitosan adsorbents. Studies were carried out using chitosan/ZIF8 composite adsorbent, and the most suitable models for chemical adsorption were determined as Langmuir isotherm and pseudo-second order kinetic model. The response surface method was applied with the design expert program to determine the optimum experimental conditions. The adsorption tests were carried out using chitosan-ECH, ZIF 8 and chitosan/ZIF 8 adsorbents for specified optimum conditions, and the humic acid removal was determined as 95.1%, 98.3%, and 97.3%, respectively. In addition, desorption was performed using chitosan-ECH and chitosan/ZIF 8 spheres, and the desorption efficiency was found to be 20.9% and 82.5%, respectively. It has been observed that the developed adsorbents have potential in removing humic acid from water.

Efficient adsorption of rhodamine B using synthesized Mg–Al hydrotalcite/ sodium carboxymethylcellulose/ sodium alginate hydrogel spheres: Performance and mechanistic analysis

In this study, the sodium dodecyl sulfate intercalated modified magnesium-aluminum hydrotalcite/sodium alginate/sodium carboxymethylcellulose (modified LDHs/SA/CMC) composite gel spheres were synthesized and their efficacies in adsorbing the cationic dye rhodamine B (RhB) from aqueous solutions were evaluated. The effects of adsorption time, pH and temperature on the adsorption of RhB by spheres were investigated. Remarkably, the modified LDHs/SA/CMC gel spheres achieved adsorption equilibrium after 600 min at 25 °C, and the removal rate of RhB at 60 mg/L reached 91.49 % with the maximum adsorption capacity of 59.64 mg/g. The gel spheres maintained over 80 % efficacy across four adsorption cycles. Kinetic and isotherm analyses revealed that the adsorption of RhB conformed to the secondary kinetic model and the Langmuir isotherm, indicating a spontaneous and exothermic nature of the adsorption process. The adsorption mechanisms of modified LDHs/SA/CMC gel spheres on RhB dyes include electrostatic adsorption, hydrogen bonding and hydrophobic interactions. In conclusion, modified LDHs/SA/CMC gel sphere is a green, simple, recyclable and efficient adsorbent, which is expected to be widely used for the treatment of cationic dye wastewater.

A novel PCM/expanded graphite composite sphere with high thermal conductivity and excellent shape stability used for a packed-bed thermal energy system

In this research, a novel phase change material (NPCM) sphere was developed and its application in a packed-bed thermal energy storage (PBTES) system during thermal energy storage was studied. Paraffin wax (PW) with a melting point of 40 °C was selected as phase change material (PCM), expanded graphite (EG) as thermal conductivity enhancement material, and epoxy resin (ER) as a surface coating. The results show that the three-dimensional heat conduction network constructed by EG foam improves the thermal conductivity of PW/EG. The thermal conductivity of NPCM is anisotropic. The thermal conductivities perpendicular and parallel to the EG compression direction are 9.03 (W/m·K) and 5.58 W/(m·K). NPCM has excellent shape stability with a leakage rate of only 2.95 %. Then, a PBTE system was built to record the temperature evolution of NPCM spheres at various inlet temperatures and volume flow rates during thermal energy storage, and thermodynamic analysis was performed. The results are as follows. (1) The temperature of the NPCM sphere near the inlet rises more rapidly and the melting time of PCM is shorter. (2) Increasing the inlet temperature improves the heat transfer and shortens the melting time of PCM while increasing the temperature inhomogeneity of the NPCM spheres. Increasing the inlet temperature increases the energy storage capacity. However, higher inlet temperature leads to lower energy efficiency and exergy efficiency. The energy efficiency and exergy efficiency are 49.66 % and 67.64 % for the inlet temperature of 60 °C, respectively. When the inlet temperature increases from 60 °C to 80 °C, the energy efficiency and exergy efficiency decrease by 16.13 % and 16.22 %, respectively. (3) Higher inlet volume flow rate also promotes heat transfer and reduces the melting time of the PCM, but has little effect on the temperature inhomogeneity of the NPCM spheres. Increasing the inlet volume flow rate does not increase the energy storage capacity. Similarly, increasing the inlet volume flow rate also results in a decrease in energy efficiency and exergy efficiency. At the inlet volume flow rate of 19.28 m3/h, the energy efficiency and exergy efficiency are 41.65 % and 56.67 %, respectively. When the inlet volume flow rate increases from 19.28 m3/h to 25.16 m3/h, the energy efficiency reduces by 7.80 % while the exergy efficiency reduces by 7.41 %. This research provides a foundation for the application of the NPCM sphere.

Three-dimensional graded porous structure and compressible KGM-GO/CS/SA composite aerogel spheres for efficient adsorption of antibiotics

The abuse of antibiotics led to significant environmental pollution through persistent residues in water bodies, posing severe risks to both ecological systems and human health. Addressing this issue, recent studies highlighted the potential of carbonaceous materials as effective adsorbents for removing antibiotics from water. Despite the proven potential of various carbonaceous materials in water purification, the application of three-dimensional porous microspherical aerogels as adsorbents presented a promising yet comparatively less discussed avenue in the quest for efficient antibiotic removal from aquatic environments.This work introduced a novel KGM-GO/CS/SA composite aerogel sphere, developed via a simple sol–gel and dripping method, using konjac glucomannan (KGM) as a cross-linking agent. We extensively analyzed its adsorption efficiency against common antibiotics such as tetracycline (TC), ofloxacin (OFL), and sulfadiazine (SDZ), revealing its rapid adsorption kinetics and high capacity. The aerogel's micro-morphology, characterized by a graded porous structure with abundant microporous channels and a low bulk density of 21.2 mg/cm3, along with its enhanced mechanical properties and thermal stability due to KGM cross-linking, signified its potential as a robust adsorbent. The surface functional groups facilitated diverse interaction mechanisms, including electrostatic attraction, hydrogen bonding, and π-π interactions, contributing to the adsorbent's high performance. Furthermore, the surface charge of the aerogel varied with pH, enhancing its electrostatic adsorption capabilities. The adsorption behavior was best described by the quasi-second-order and Langmuir models, with maximum capacities of 427.63 mg/g for OFL, 374.35 mg/g for TC, and 231.09 mg/g for SDZ, thereby offering a promising solution for antibiotic pollution remediation and illustrating the utility of carbon-based aerogel microspheres in environmental applications.

Highly Uniform Nanodiamond-Graphene Composites Microspheres for Electrocatalytic Hydrogen Evolution.

To progress the clean hydrogen-gas-based energy economy, there is a demand for cost-effective, highly efficient catalysts to facilitate the hydrogen evolution reaction process (HER). Due to the amazing catalytic capabilities of two-dimensional materials, extensive research has been done on these structures. However, most of the described syntheses take a lot of time, are challenging, and are ineffective. The present work demonstrates the performance of the recently reported nanodiamond/graphene composite microsphere ND-GCSs as a catalyst for HER. These spheres were produced via the microwave-irradiation approach. A modified process was adopted to improve the particle size uniformity and yield. The prepared composite spheres showed very interesting catalytic activity for the HER when assembled on a screen-printed carbon electrode. The prepared ND-GCSs@SPCE showed a significant shift of the onset potential to ca. -450 mV and a small Tafel slope value of ca. 85 mV/decade. The electron transfer was drastically enhanced with a tremendous decrease in charge transfer resistance to ca. 265 Ω. The electrocatalyst showed excellent long-term stability for the HER application. Additionally, this novel composite structure might be beneficial for diverse applications including batteries, supercapacitors, catalyst supports, and more.

Recovery and regeneration of water-hardened magnetic composite biochar sphere for the removal of multiple heavy metals in contaminated soils

Biochar has exceeded expectations for immobilizing heavy metals (HMs), but the potential ecological risks of its long-term burial in soil limit its practical application on a large scale. To address this challenge, a novel separable water-hardened magnetic composite biochar sphere (WMBCS) was prepared and applied to remediate agricultural soils contaminated with Cd, Pb, and As. The first application of WMBCS is simultaneously effective in removing Cd (3.2–12.7%), Pb (3.3–13.1%), and As (5.0–25.6%) from soil, and the removal rates are enhanced with increasing soil moisture, application dose and incubation time. WMBCS is more efficient for removing Cd and Pb in mildly contaminated alkaline soils than in heavily contaminated acidic soils. Compared with other regeneration methods, shaking and ultrasound-assisted EDTA-2Na efficiently elutes HMs with a dissolution efficiency of over 75% within 4 h, accompanied by the lowest rate of mass loss (7.6%) and Fe leaching (475.1 mg kg−1). After 5 rounds of successive cyclic remediation, WMBCS exhibits high adsorption efficiency (26.5–30.6% for Cd, 25.4–30.2% for Pb, and 30.2–41.0% for As), magnetic separation efficiency (98.8–99.8%) and regeneration efficiency (92.3–95.4%). The main mechanisms involved in the adsorption and regeneration of WMBCS include ion exchange and chelation. WMBCS is an economical and eco-friendly material with vast unexplored potential for use in agriculture.

Preparation and characterization of silver-carbon composite semitransparent hollow microspheres for surface-enhanced Raman scattering

In this work, silver-carbon composite semitransparent hollow spheres (Ag/HCSs) have been successfully synthesized via hydrothermal carbonization (HTC) with trioctylamine (TOA) as a stabilizer and soft template. Furthermore, silver-carbon composites with core-shell structure (Ag@CSs) and carbon films loaded with silver nanoparticles composites with lamellar structure (Ag/CFs) were prepared by adjusting the amount of TOA. The Ag/HCSs were composed of a matrix of ultrathin translucent hydrothermal hollow carbon microspheres with Ag nanoclusters embedded, and numbers of Ag@CSs inside and outside of the hollow carbon microspheres. We further investigated the growth mechanism and morphology evolution, on the basis of the properties of Ag and HCSs, explored the application of the Ag/HCSs for surface-enhanced Raman scattering (SERS). SERS activity was investigated using Rhodamine 6 G (R6G) and crystal violet (CV) as the SERS probe molecules. Ag/HCSs exhibit the best SERS performance among three products. The semitranslucent carbon shell, localized surface plasmon resonances of AgNPs and the effect of charge transfer arising from oxygen-containing moieties make the Ag/HCSs to exhibit good SERS performance, which may give a little inspiration to prepare novel SERS substrates.

Hollow Ti3C2Tx MXene sphere-based ZIF-67 derived central radiative cobalt-tipped carbon nanotubes electrocatalysts for ORR and OER

The oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) plays a key role in many renewable energy conversion and storage technologies. As the state-of-the-art ORR and OER electrocatalysts, noble-metal-based electrocatalysts suffer from high price, low earth abundance, single functionality, and poor stability. Developing high performance noble-metal-free ORR and OER bifunctional electrocatalysts as alternatives is highly desirable but remains a significant challenge. In this work, we reported a metal-organic-framework-engaged strategy for the fabrication of central radiative cobalt-tipped N-doped carbon nanotube/hollow Ti3C2Tx sphere composites (h-Ti3C2Tx@Co-NCNT), in which ZIF-67 particles were in situ grown on spherical structure composed of Ti3C2Tx nanosheets constructed with hard template PMMA and then were converted to cobalt-tipped N-doped carbon nanotubes through a pyrolysis process. The hollow Ti3C2Tx nanosheets sphere not only served as conductive scaffolds for the growth of Co-NCNT but also balanced the tradeoff between graphitization of carbon and the surface area. Benefiting from the abundant Co-N/C active sites, reasonably high graphitization of carbon and suitable surface areas, the optimized h-Ti3C2Tx@Co-NCNT manifested comparable ORR (half-wave potential of 0.843 V) and OER (overpotential of 323 mV) activities. In addition, the h-Ti3C2Tx@Co-NCNT assembled zinc-air battery exhibits superior performance beyond commercial Pt/C+RuO2. Certificating this strategy can provide great opportunity for its application in renewable conversion and storage technologies.

Tin-carbon composite submicron spheres constructed by molten salt synthesis and their high lithium storage performance

To effectively alleviate the severe agglomeration and huge volume expansion of tin oxides during charge and discharge processes, tin-carbon composite (SnOx@C-M) submicron spheres are constructed in this work using a molten salt-assisted method to improve their lithium storage performance. SnOx@C-M submicron spheres mainly comprises SnOx nuclei encapsulated by an amorphous carbon layer. The aggregation of SnOx nanoparticles can be enhanced by the surface carbon layer, allowing the significant volume expansion during cycling to be buffered. As expected, decent cycling stability and multiplicative properties were realized in the SnOx@C-M electrode material. Hence, this work is expected to provide a workable method to improve the performance of tin-carbon composites.

Experimental study on the effect of basalt fiber reinforced expanded polystyrene foams on the compressive strength of lightweight concrete

Reducing the structural load and operational energy consumption of buildings is a trend in the development of the construction industry, and lightweight concrete has become a research hotspot because of its dual characteristics of low density and high strength. In this paper, a three-step method is used to prepare lightweight concrete composites. In the first step, basalt fiber powder was adhered to polystyrene foam ball expanded polystyrene spheres (EPSs) by the “ball rolling method” to obtain basalt fiber reinforced epoxy composite balls. In the second step, the epoxy resin composite ball and the configured cement matrix are filled into a prefabricated mold. Finally, the lightweight concrete specimens were overlaid, pressed into shape, and cured for 28 days. By changing the volume ratio, size, and wall thickness of the epoxy composite balls, as well as the length and content of basalt fibers, the lightweight concrete was exhibited a reduction in density and increase in strength. The results showed that the smaller the epoxy composite spheres and the larger the wall thickness are, the higher the compressive strength of the material for a certain volume ratio of epoxy composite spheres will be. The addition of appropriate hollow glass beads can reduce the number of pores in the matrix, but excessive hollow glass beads will reduce the bonding force of the concrete matrix. Basalt fibers not only improve the strength of EPSs but also serve to connect matrix–matrix and matrix–epoxy composite spheres.

Zn-Doped MnCO3/CS Composite Photocatalyst for Visible-Light-Driven Decomposition of Organic Pollutants.

Zn-doped MnCO3/carbon sphere (Zn-doped MnCO3/CS) composites were synthesized using a simple hydrothermal procedure. Among various samples (ZM-50, ZM-05, and ZMC-0), the ternary Zn-doped MnCO3/CS (ZMC-2) catalyst demonstrated excellent visible light-induced photocatalytic activity. This improvement comes from the Zn addition and the conductive CS, which facilitate electron movement and charge transport. The catalyst exhibited efficient degradation of methylene blue (MB) over a wide pH range, achieving a removal efficiency of 99.6% under visible light. Radical trapping experiments suggested that •OH and •O2- played essential roles in the mechanism of organic pollutant degradation. Moreover, the catalyst maintained good degradation performance after five cycles. This study offers valuable perspectives into the fabrication of carbon-based composites with promising photocatalytic activity.

Discerning the catalytic treatment of cationic dye wastewater in photoreactor comprising ternary (Co3+/Co2+)-embedded SnO2/ZnFe2O4 composite sensitive toward ultra-violet illumination.

Herein, magnetic (Co3+/Co2+)-integrated SnO2, SnO2/ZnFe2O4, and ZnFe2O4 composites have been prepared from triply distilled water and 30% of isopropanol in the water medium. The phase evolution, microstructure, and magnetism were investigated successfully and tested for cationic dye wastewater degradation containing Rhodamine 6G and Methylene Blue under ultra-violet irradiation. Composite spheres are attributed to efficient heterojunction interfaces between ZnFe2O4 and SnO2 semiconductors with the support of (Co3+/Co2+) nanoparticles. The results provide a simple, low-cost, environmentally friendly, and scalable method of ternary composites to degrade mixed dyes. Co3+/Co2+-implanted SnO2/ZnFe2O4 offered narrowed bandgap energy, more light absorption, diminishing electron-hole recombination, and more charge carriers toward cationic dye wastewater than the binary components. The rate constant of Rhodamine 6G degradation was observed at 0.0237min-1, and Methylene Blue degradation was observed at 0.0187min-1 at 90min under UV (λ = 365nm) irradiation. Capturing studies of various organic reactive species and mechanisms of composites was also proposed in detail.

Determination of catechol in tea based on the inhibition of CS@Cd composites electrochemiluminescence

To address growing concerns about food safety, sensors for catechol (CA) have been urgently needed. In this work, cadmium-coated carbon spheres (CS@Cd) composites are prepared via hydrothermal synthesis and further used to fabricate a CS@Cd modified glassy carbon electrode (CS@Cd/GCE). Importantly, CS@Cd has good sensitization effect on the electrochemiluminescence (ECL) of luminol-H2O2 system. Besides, CA is able to inhibit the ECL of CS@Cd/GCE owing to the consumption of H2O2 induced by CA, and thus a novel strategy for ECL detection of CA is formulated. At optimum conditions, CS@Cd/GCE exhibits good linear relationship in the range of 1.0 × 10-11 ∼ 1.0 × 10-4 mol·L-1 with a low limit of detection of 2.5 × 10-12 mol·L-1 (S/N = 3). Finally, this method achieves a satisfactory outcome for the detection of CA in tea samples.

Highly sensitive electrochemical sensing of norfloxacin by molecularly imprinted composite hollow spheres

Poly (3,4-ethylenedioxythiophene) (PEDOT)-based molecularly imprinted electrochemical sensors have attracted widespread attention for monitoring contaminants in food and the environment. However, there are still problems such as poor hydrophilicity, easy agglomeration, and low selectivity in its preparation. In this work, a novel molecularly imprinted composite hollow sphere was prepared by a molecular imprinting technique using nitrogen-doped hollow carbon spheres as matrix material, and PEDOT and poly(methacrylic acid) as monomers. The selective binding capabilities and mechanism of the material to norfloxacin (NOR) were systematically investigated. Then the material-based sensor was constructed, and its electrochemical detection performance toward NOR was thoroughly studied. The sensor exhibited a wide linear range (0.0005–31 μM), a low detection limit (0.061 nM), satisfactory immunity to interference and stability. Besides, the sensor displayed better sensitivity and reliability (spiked recoveries of 98.0–105.2%, relative standard deviation of 3.45–5.69%) for detecting NOR in lake water, honey, and milk than high-performance liquid chromatography. This work provides a new strategy for developing poly(3,4-ethylenedioxythiophene)-based molecularly imprinted electrochemical sensors.

Solvothermal synthesis of porous FeOx–CeO2−y composite spheres with high mixing homogeneity

FeOx–CeO2−y composites with different homogeneities were synthesized by the solvothermal method, co-precipitation, and physical mixing. FeOx and CeO2−y in the composites synthesized by the solvothermal method and co-precipitation were homogeneously mixed at the nanometer scale, but physical mixing afforded heterogeneously agglomerated composites. The effects of the homogeneity of the composites were evaluated by probe reverse water-gas shift (RWGS) reaction. The improved homogeneity of FeOx and CeO2−y in the composites resulted in higher catalytic activity, product selectivity, and long-term stability in the RWGS reaction at 700 °C. The redox behavior of FeOx was enhanced by finely combined CeO2−y in the case of solvothermally prepared FeOx–CeO2−y, which exhibited excellent crystal structure stability. This study demonstrates the advantages of using the solvothermal method in obtaining homogeneous composites containing multiple metal oxides.

PH-Regulated host-guest architecture in molybdenum Dioxide/Carbon sphere composites for flexible solid-state supercapacitors

Compositing molybdenum dioxide (MoO2) with carbon sphere (CS) can greatly enhance the conductivity and structural instability to achieve its high theoretical capacitances. The controllable regulation of local architecture and host–guest interaction in the two-phase composites is highly desirable, but commonly hindered by the significant difference in formation mechanism between MoO2 and CS. Herein, a pH-regulated pre-intervention strategy was developed to provide control over the MoO2/CS architecture by adjusting the interplay between the precipitation kinetics of MoO2 and the polymerization effect of hydrochar precursor. By varying the pre-synthesis pH from 10.0 to 0.1, the corresponding dominant formation process of precursor changes from inside-out Ostwald ripening to protonation-induced electrostatic interactions, resulting in the structural evolution of MoO2/CS from hollow CS-encapsulating MoO2 nanosheets and solid CS-supporting MoO2 nanoparticles. The electrochemical test proved the former architecture possesses faster electrode kinetics, lower charge/ion-transfer resistance, and better electrochemical stability. An extended oxidation-etching method was further introduced to prepare mesoporous CS with excellent supercapacitive properties. A flexible solid-state asymmetric supercapacitor composed of optimal MoO2/CS structure as the positive electrode and mesoporous CS as the negative electrode delivers a high energy density of 52.3 W h kg−1 and power density of 14500 W kg−1, and good cycling stability with 89.7 % retention of the initial capacitance after 8000 cycles.

Floatable Chitosan Composite Spheres Based on Nanoscale Donor–Acceptor Type g-C3N4 with Enhanced Photogenerated Carriers and ROS Generation for Photocatalytic Degradation of Malachite Green in Aquaculture

Floatable Chitosan Composite Spheres Based on Nanoscale Donor–Acceptor Type g-C₃N₄ with Enhanced Photogenerated Carriers and ROS Generation for Photocatalytic Degradation of Malachite Green in Aquaculture

Влияние температуры стадии формования и нейтрализации на свойства сферического носителя катализаторов риформинга, получаемого методом масляного формования

The work is devoted to the study of an oil-drop method for the production of spherical alumina used as a carrier for reforming catalysts with continuous regeneration. The mechanism of transformations occurring during spherical alumina forming by the oil-drop method from mixture of aluminum oxychloride and urotropin used as a gelling agent is proposed. The semi-quantitative composition of spheres after the neutralization stage is calculated on the basis of physicochemical methods of analysis. The possibility of obtaining spherical alumina with different physicochemical properties by varying temperature of the forming and neutralization stage is shown. Increasing the temperature of the neutralization stage leads to a narrower pore size distribution - the formation of more uniform pores with a smallercontribution of pores with a diameter greater than 170 angstroms. The strength of the obtained alumina is significantly affected: the strength increases several times with increasing the temperature of the neutralization stage.

Zeolite/slag-based porous geopolymer sphere regenerable composites with enhanced mechanical strength and good dye removal performance

Porous slag-based geopolymer spheres were synthesized by a suspension-solidification method using silicone oil as suspending bath. Zeolite powder, expected to improve or optimize the mechanical and/or adsorption properties, was used as second phase. The porous morphology, structure change, specific surface area, porosity, mechanical properties as well as adsorption capacity of the porous solid waste-based sphere composites were investigated. The mechanical strength was significantly improved by the addition of zeolite, along with a slight decrease for methylene blue adsorption properties. The obtained porous slag-based zeolite/geopolymer spheres with high porosity and acceptable strength have potential application as low cost and high effective adsorption composite materials.