Conventional Hydrothermal Method Research Articles

Synthesis, structure and characterization of two new silver-iron based phosphates AgFe2(PO4)2F(H2O)2 and Ag3Fe2(PO4)(HPO4)3

Two new silver-iron based phosphates AgFe2(PO4)2F(H2O)2 (1) with monoclinic P21/n and Ag3Fe2(PO4)(HPO4)3 (2) with triclinic P-1 were synthesized by a conventional hydrothermal method, featuring a dimer structure and a twisted honeycomb-like lattice, respectively. XPS and BVS (Bond Valence Sum) calculations indicated only Fe3+ ions in both compounds, while FT-IR spectra proved the presence of [H2O] in 1 and [OH] groups in 2. Solid-state UV–vis–NIR diffuse reflectance spectra suggested their wide optical band gaps of 2.31 eV and 1.94 eV, respectively. Magnetic measurements indicated that both compounds display a long-range antiferromagnetic ordering at low temperature, showing the change of magnetic entropy of 9.59 J·mol-1·K-1 in 1 and that of 14.87 J·mol-1·K-1 in 2, respectively.

A new S = 2 kagomé lattice compound with ferromagnetic behaviors

A new compound NaMn3(SeO3)2(HSeO3)6 was obtained by a conventional hydrothermal method. This compound crystallizes in a trigonal system with space group R-3, exhibiting a typical kagomé structure, where the kagomé layers are composed of [MnO6] octahedra linked by [SeO3] groups. Magnetic susceptibility measurements confirm that this compound exhibits a ferromagnetic transition at ∼13 K, as further confirmed by the heat capacity data. The magnetic entropy was estimated, indicating that the system may release almost the entire entropy at low temperature.

A novel nanozyme doped ZnO/r-GO-based sensor for highly sensitive electrochemical determination of muscle-relaxant drug: cyclobenzaprine HCl.

A nanocomposite of Ce-doped ZnO/r-GO was synthesized using a conventional hydrothermal method. The synthesized nanocomposites were utilized for the purpose of sensitive and selective detection of cyclobenzaprine hydrochloride (CBP). The properties of the composite were extensively analyzed, including its morphology, structure, and electrochemical behavior. This study investigates the application of a modified glassy carbon electrode for the detection of CBP, a muscle relaxant used to treat musculoskeletal diseases that cause muscle spasms. The electrode is modified with Ce-doped ZnO/r-GO. Various detection methods, such as cyclic voltammetric and square wave techniques (SWV), were utilized. The composite material showed high effectiveness as an electron transfer mediator in the oxidation of CBP. The electrode showed a good response for SWV evaluations in CBP identification, with a minimum detection limit of 1.6 × 10-8M and a wide linear range from 10 × 10-6 M to 0.6 × 10-7 M, under ideal conditions. The rate constant for charge transfer (ks) and the estimation of the electrochemical active surface area were obtained. A developed sensor exhibited desirable selectivity, long-lasting stability, and remarkable reproducibility. A sensor was used to analyze water, human serum, and urine samples, resulting in positive recovery results.

Solvent Effect on the Structural, Optical, Morphology, and Antimicrobial Activity of Silver Phosphate Microcrystals by Conventional Hydrothermal Method.

The design of particle size and morphology are a promising approach to investigating the properties exhibited by different types of materials. In the present study, the silver phosphate microcrystals (Ag3PO4) were first time synthesized using the hydrothermal and solvothermal method by combination of the solvents water/isopropyl alcohol (SP-IA), water/acetone (SP-AC), water/ammonium hydroxide (AP-AH), all in a ratio of 1:1 (v/v). The synthesized materials were structurally characterized by X-ray diffraction (XRD), Rietveld refinement, and Raman vibrational spectroscopy, where it was confirmed that the pure phase was achieved for all prepared samples. The study of the optical properties by UV-vis diffuse reflectance spectroscopy (UV-vis/DRS) and colorimetry revealed that the obtained materials have an optical bandgap between 2.30 and 2.32 eV. The FE-SEM images collected revealed different morphologies for the synthesized materials, with a predominance of tetraploid-shaped microcrystals for the SP-AC sample, rods for the SP-IA sample, cubes and polyhedral for the SP-WT sample and condensed polyhedral for the SP-AH sample. The photocatalytic performance against the Rhodamine B dye (RhB) was 100%, 98.2%, 94.2%, and 87.8%, using the samples SP-AC, SP-IA, SP-WT, and SP-AH as photocatalyst at time of 12 min. On the other hand, the antimicrobial performance of SP-AC sample showed superior performance, resulting in the minimum inhibitory concentration-MIC of 7.81 μg mL-1 for the strain of E. coli, 7.81 μg mL-1 for the strain of E. aureus, 15.62 μg mL-1 for the strain of P. auruginosa, and 15.62 μg mL-1 for the strains of C. albicans. In this way, was synthesized a promissory antimicrobial and photocatalyst material, through an easy and cost-effective method.

MgHg(SeO3)2(H2O)2: A magnesium mercury selenite with large birefringence

Selenite crystalline materials have been popular owing to the diverse structures and optical performances. A new mercury selenite, MgHg(SeO3)2(H2O)2, was synthesized by using a conventional hydrothermal method. It crystallizes in the monoclinic structure with a C2/c space group, MgHg(SeO3)2(H2O)2 exhibits a three-dimensional (3D) structure, which is made up of [Hg(SeO3)2]2–∞ chains and distorted MgO4(H2O)2 octahedra. Besides, it presents a large birefringence of 0.137 @ 546 nm according to experimental measurement. Synthesis, crystal structure, thermal stability, optical property measurements and theoretical studies were performed in this work.

Plant-Mediated Synthesis of Magnetite Nanoparticles with Matricaria chamomilla Aqueous Extract.

Magnetite nanoparticles (NPs) possess properties that make them suitable for a wide range of applications. In recent years, interest in the synthesis of magnetite NPs and their surface functionalization has increased significantly, especially regarding their application in biomedicine such as for controlled and targeted drug delivery. There are several conventional methods for preparing magnetite NPs, all of which mostly utilize Fe(iii) and Fe(ii) salt precursors. In this study, we present a microwave hydrothermal synthesis for the precipitation of magnetite NPs at temperatures of 200 °C for 20 min and 260 °C for 5 min, with only iron(iii) as a precursor utilizing chamomile flower extract as a stabilizing, capping, and reducing agent. Products were characterized using FTIR, PXRD, SEM, and magnetometry. Our analysis revealed significant differences in the properties of magnetite NPs prepared with this approach, and the conventional two-precursor hydrothermal microwave method (sample MagH). FTIR and PXRD analyses confirmed coated magnetite particles. The temperature and magnetic-field dependence of magnetization indicate their superparamagnetic behavior. Importantly, the results of our study show the noticeable cytotoxicity of coated magnetite NPs-toxic to carcinoma cells but harmless to healthy cells-further emphasizing the potential of these NPs for biomedical applications.

Synthesis of zeolite X from fly ash in an impinging stream reactor and its mechanisms

The conventional hydrothermal method with magnetic stirring for the synthesis of zeolite X from fly ash has some problems, such as low micromixing efficiency, low mass transfer rate, and long synthesis time. In this study, impinging stream reactor is used to improve the mass transfer and micromixing and the mechanism how the nucleation and crystallization of zeolite is accelerated is explored. The results show that premixing in the impinging stream reactor can reduce the stirring and aging time from 4 h to 20 min because the hydroxyl free radicals resulting from the cavitation effect can accelerate the crystallization of zeolite. After collision, the viscosity of the system is increased from 0.22 Pa·s to 3 Pa·s, which can increase the residence time of cavitation bubbles in the gel solution and effectively inhibit the aggregation of crystal nuclei. As a result, the crystal nuclei in the system are well dispersed. The impinging stream reactor can also accelerate the mass transfer between liquid and solid phases and improve the micromixing of raw materials, so that the polymerization between Si and Al is increased and the nucleation of zeolite X is accelerated. The degree of order of zeolite X samples obtained by premixing in the impinging stream reactor is much higher than that obtained by magnetic stirring. The relative crystallinity after crystallization for 12 h (100 %) is higher than that obtained by magnetic stirring (94.93 %); and the n(Si/Al) is lower than that obtained by magnetic stirring. It is concluded that premixing in the impinging stream reactor can improve the polymerization of aluminosilicate and accelerate the nucleation and crystallization of zeolite X. Under the same conditions, zeolite X synthesized by premixing in the impinging stream reactor has better CO2 adsorption capacity than those synthesized by magnetic stirring and industrial synthesis.

Application of NiFe2O4 nanoparticles towards the detection of ovarian cancer marker

In this work, we explored the potential application of NiFe2O4 magnetic nanoparticles in sensing platforms due to their cost-effectiveness and good magnetic properties. The spinel-type metal oxide was prepared using the conventional hydrothermal synthesis method. The structural, morphological, and magnetic properties of the as-synthesized NiFe2O4 nanoparticles were discussed. The nanoparticles were functionalized with cystamine, glutaraldehyde, and PVDF and then modified with the CA 125 antibody to obtain the immunosensor. FTIR and electrochemical analyses reveal immobilization of the antibody on the surface of the NiFe2O4 magnetic nanoparticles. The immunosensor developed in this work was made on a printed circuit board, allowing it to be used as a point-of-care device. The immunosensor showed excellent stability, reproducibility, specificity, and selectivity. Our findings are of great significance for developing novel, high-performance point-of-care electrochemical biosensors to be applied in detecting the CA 125 antigen, a widely used biomarker for the prognosis of ovarian cancer.

Sb/X (X = Mn, Er, Ho) Co‐Doped Lead‐Free Double Perovskite Cs2NaInCl6 for Single‐Component White Light Emission

AbstractRecently, the incorporation of transition‐metal ions into lead‐free double perovskite has garnered considerable attention for improving the lattice environment and enhancing photoluminescence (PL) to achieve white light emission. Here, Sb/X (Mn, Er, Ho) co‐doped Cs2NaInCl6 (CNIC) microcrystals (MCs) synthesized by conventional hydrothermal method are developed for single‐component white light emission with various photoinduced transition mechanisms. Sb doping in CNIC MCs causes the breaking of non‐parity forbidden transition under 360 nm laser excitation and results in blue emission; Sb/X co‐doping for CNIC MCs successfully broadens the spectrum with multi‐peak emission, which consists of unique X‐peak emission and blue emission peaked at 445 nm. The energy transfer channels from both free excitons state of CNIC and self‐trapping excitons (STEs) state of [SbCl6]3− to X ion are proved and studied by use of steady‐state and time‐resolved PL spectroscopy. Among them, Sb/Er co‐doped CNIC MCs show unique dual‐mode PL under 360 and 980 nm laser excitation. Single‐component white light emitting diode is successfully fabricated by adjusting the composition of Sb/X co‐doped CNIC MCs, which provides an alternative path for realizing single‐component white light illumination.

Photocatalytic activity enhancement by noble metal deposition on faceted F-TiO2 synthesised by microwave assisted method. A study of selective oxidation of gas-phase ethanol in a FBPR reactor

In the present work, fluorinated titanium dioxide (TiO2-F) with high exposition of facet {001} was prepared by following a facile and high yield hydrothermal method assisted by microwave. This faceted TiO2 was then modified by Au or Ag deposition at two different metal loadings (0.125 and 0.25 wt%). A wide physicochemical characterisation of the materials was performed. X-ray difractograms showed high {001} facet exposition in all materials. By X-ray fluorescence it was found that the different samples contained about 5% of fluor. All samples presented high surface area and high uniformity and homogeneity of particles, which highlights the good properties that can be achieved by the microwave synthesis method compared to conventional hydrothermal methods. Oxidation state of the noble metals was studied by XPS. On the other side, TiO2-F and the metallised titania powders were immobilised on polystyrene pellets (PS) for evaluating their gas photocatalytic activity in volatile organic compounds (VOCs) decontamination by following the reaction of photoxidation of ethanol in gas phase. It was found that activity was considerably improved by the addition of noble metals, obtaining high conversion and selectivity to CO2. It is remarkable that the selectivity to CO is almost zero. The highest efficiency was found for the faceted TiO2-F sample with the lowest Au loading (0.125 wt%) immobilised on PS where 91% ethanol conversion and 100% CO2 selectivity were achieved. Different reaction variables were also studied.

Structure, dielectric and magnetic properties of hydrothermally synthesized Sn1−x Fe x O2 nanoparticles

Abstract Sn1−x Fe x O2 (x = 0, 1, 2, 3, and 4 %) of the diamagnetic/ferromagnetic phase were synthesized by the conventional hydrothermal method. X-ray diffraction spectra confirm that all the samples have a tetragonal structure. Electronic distribution over the unit cell of Sn1−x Fe x O2 showed the dependence of electronic density on the x. The crystallite size of the obtained samples was in the range of 42–72 nm. Impedance spectroscopy was employed to investigate the variation of the electrical impedance and some related parameters as frequency functions in the range of 75 k Hz–10 MHz at room temperature. The dielectric behavior was explained using the Maxwell–Wagner model of interfacial polarization. The ac conductivity results were used to evaluate the maximum barrier height, the minimum hopping distance, and the density of the localized states at the Fermi level. The effect of adding the iron ion into the tin dioxide compound was apparent, as the electrical and magnetic properties as well as the morphology were affected, although the crystal structure phase still has the same tetragonal crystal system for the different iron concentration (Fe from x = 0 up to x = 0.04) with slight variation in the lattice constants. The magnetic measurements illustrated that the Fe-doped SnO2 nanoparticles exhibit ferromagnetic ordering at room temperature. Variation of the Fe content affects the ferromagnetic characteristics of the samples.

Electrodeposited graphene@TiO2 nanosheets for enhanced photocathodic protection

In this work, TiO2 was firmly attached on freestanding graphene (Gr, rather than graphene oxide or reduced graphene oxide) nanosheets (Gr@e-TiO2) by a novel electrodeposition method. The morphology, crystal structure, band gap characteristics, optical properties and photoelectric properties were systematically investigated. It is indicated that the absorption of visible light increased and the recombination of photogenerated electron-hole pairs decreased for the as-obtained Gr@e-TiO2. Compared with pure TiO2 as well as GO (graphene oxide)@h-TiO2 prepared by conventional hydrothermal method, Gr@e-TiO2 exhibited a more negative open circuit potential and higher photocurrent density for 304SS protection. The enhanced photocathodic protection performance of Gr@e-TiO2 can be attributed to the large specific surface area and good charge transport efficiency of graphene.

Two Short-Wave UV Antimony(III) Sulfates Exhibiting Large Birefringence.

In the present work, we have successfully obtained two new UV antimony-based sulfates, NH4Sb(SO4)2 and Ca2Sb2O(SO4)4, by a conventional hydrothermal method. Interestingly, both compounds share similar structural building blocks, such as SbO4 seesaws and SO4 tetrahedra, yet they endow discrepant birefringence values measured at 546 nm with values of 0.150 and 0.114, respectively, owing to the different distortions of the SbO4 groups with SCALP electrons. Moreover, both compounds display large band gaps (4.32 and 4.43 eV, respectively), so they can be used as short-wavelength UV birefringent materials. Moreover, NH4Sb(SO4)2 is a noncentrosymmetric compound, showing a frequency doubling effect of 0.2 × KDP. Detailed structural analyses and calculations confirm the source of superior optical performance and the reasons for the different birefringence of the two compounds. This work provides ideas for the following discovery of antimony-based optical materials with excellent properties.

Room temperature synthesized layered CAU-17 MOFs for highly active and selective electrocatalytic CO2 reduction to formate

Modulating the morphology of metal-organic frameworks (MOFs) has been identified as an effective strategy for enhancing the electrocatalytic performance of CO2 reduction reactions (CO2RR). In this study, CAU-17 MOFs ([Bi(BTC)(H2O)]·2 H2O·MeOH) were prepared via a sonication-assisted method at room temperature, which is considered a simpler technique compared to the conventional hydrothermal method. Additionally, the morphology of CAU-17 MOFs was further regulated by incorporating a rare-earth metal (La), resulting in the observation of two distinct structures, i.e. CAU-17 hexagonal prism (CAU-17-HP) and CAU-17 layer (CAU-17-Layer). Compared to CAU-17-HP, CAU-17-Layer exhibits an excellent selectivity towards formate with the maximum Faradaic efficiency of 95.5% at − 1.1 VRHE in an H-cell. Subsequently, the limited catalytic activity of CAU-17-Layer was boosted by anchoring nano CeO2 onto its surfaces (CeO2 @CAU-17-Layer). The as-prepared composite catalyst demonstrated outstanding performance in the conversion of CO2 to formate, with a current density surpassing − 100 mA cm-2 at potentials more negative than − 1.0 VRHE and reaching − 200 mA cm-2 at − 1.5 VRHE in a flow cell. This study demonstrates the significant potential of morphology-engineered and rare-earth metals composited MOFs in facilitating highly efficient reduction of CO2.

Nano-ZnS photocatalytically active both under UV and solar radiation: A comparison of conventional and microwave-assisted hydrothermal syntheses with various reaction conditions

Influence of reaction conditions on properties of nano-ZnS was investigated. The nano-ZnS was synthesized from ZnCl2 and Na2S via conventional hydrothermal (H) and microwave-assisted hydrothermal (M) method with reaction times 90, 150, 210 min and 10, 20, 30 min, respectively. For all reaction times, three nZn:nS molar ratios (1:1; 1.5:1; 2:1) were tested. Samples were characterized by XRPD, FTIR, Raman microspectroscopy, UV–VIS and SEM. Photocatalytic activity (PA) was determined on Acid orange 7 under UV radiation (λ = 365 nm), and for selected samples also under the sunlight. After 360 min of UV radiation, PA 96% (H; 210 min; 1:1, 1.5:1 or 2:1) and 92% (M; 30 min; 1.5:1 or 2:1) was reached. Under the sunlight, PA 96% (H; 210 min; 2:1) and 92% (M; 20 min; 2:1) was achieved after 120 and 540 min, respectively. M-synthesized nano-ZnS is promising for outdoor applications not requiring a fast PA effect.

Synthesis of Nanosized Zeolite Catalyst Particles from Waste Materials for Efficient Removal of Fe(III) from aqueous solution

The objective of this study was to prepare zeolite ZSM-5 nanostructure from aluminum foil drug sachet waste by a simple conventional hydrothermal method using different times (24, 48, 72, and 96 h), and to figure out the adsorption capacity of zeolite ZSM-5 nanostructure for heavy metal of Fe(III) . The best time for synthesizing and testing the adsorption effectiveness of the provided ZSM-5 zeolite is 96 h. The ZSM-5 zeolite is defined by X-ray diffraction (XRD), Brunauer Emmett Teller (BET), Field Emission Scanning Electron Microscopy (FESEM) and Fourier transform infrared spectroscopy (FTIR) for confirming their structure and properties, such as crystal structure, surface area, and surface morphology. The crystallinity percentage of nanosized ZSM-5 was 100%, and the surface area and micropore volume were 368.70 m2/g and 0.158 cm3/g, respectively. In addition, the ZSM-5's adsorption efficiency the solution for Fe(III) was tested. Many factors, including adsorption properties, contact duration, initial iron solution content, and pH, were investigated. The equilibrium was reached after 25 minutes. pH levels between 3.0 and 4.0 were shown to be optimal for the absorption of iron solution. The iron species` adsorption capacities in solutions at 298 K were 56.49 mg/g, at 308 K, 86.20 mg/g, and at 318 K, 68.02 mg/g. The findings of the Freundlich adsorptions and Langmuir were used to represent the isotherm constants. The Langmuir model can adequately describe the Fe(III) solutions` adsorption isotherm data while testing at 298K and 308K, whereas those of Fe(III) testing at 308K and 318K were more closely connected to the Freundlich model.

A carbon quantum dot based on tetramethyl substituted cucurbit[6]uril and 2,7-dihydroxynaphthalene: Selective detection of Fe3+, ClO−and I−

Carbon quantum dots have attracted much attention as novel nanomaterials. In this study, TMeQ[6]-CQDs were synthesized by a conventional hydrothermal method using symmetric tetramethyl-substituted cucurbit[6]uril (TMeQ[6]) and 2,7-dihydroxynaphthalene (DHN) as carbon precursors, which characterized by 1H NMR, UV–vis, FL, SEM, FTIR, and XPS. Futhermore, the crystal structure was determined using Single crystal X-ray crystallography, demonstrating the formation of TMeQ[6]-based supramolecular assemblies (TMeQ[6]-DHN-[CdCl4]2−). The prepared TMeQ[6]-CQDs have abundant oxygen-containing groups with excellent water-solubility and fluorescence properties. Subsequently, using the obtained TMeQ[6]-CQDs, a universal fluorescent probe was prepared for detecting and recognizing Fe3+, I−, and ClO−. In the presence of Fe3+and I− ions, the fluorescent CQDs are quenched. Interestingly, the fluorescence spectral line undergoes a red-shift when interacting with ClO−. The detection limits were 0.41 μM, 3.71 μM and 0.10 μM.

Self-enhancement of phosphorus recovery from anaerobic fermented sludge with MOF-808 synthesized with an improved green method

Although sludge anaerobic fermented is rich in phosphate, its complicated composition might be a barrier for adsorption approach due to the competing effects of ions and organics. In this study, an interesting phenomenon was found with MOF-808-(25) which exhibited a higher adsorption capacity in anaerobic fermented sludge than in phosphate-water solution. A green synthesis of MOF-808-(25) was first developed by optimizing the microwave synthesis method to reduce the cost of the adsorbent. Under the optimized conditions, i.e., Zr4+/BTC3− ratio of 4:1, 25 min, and microwave power of 350 W, the space–time yield of MOF-808-(25) reached 236.03 kg·m−3d−1, approximately 100 times higher than those achieved through conventional hydrothermal methods. In phosphate-water solution, the maximum adsorption capacity of MOF-808-(25) for phosphate was 66.61 mg P/g (pH = 7, 25 °C). Molecular dynamics simulation revealed that the adsorption of phosphate by MOF-808 was primarily dominated by coordination effects, while, electrostatic interactions, hydrogen bonding, and steric hindrance were also involved. MOF-808-(25) exhibited good adsorptive selectivity over coexisting anions and organic matters in anaerobic fermentation broth. Experimental results also suggest that a higher temperature or a lower pH value favored the adsorption capacity of MOF-808-(25). With this feature, the phosphate adsorption capacity of MOF-808-(25) was surprisingly ∼ 5 mg P/g higher than that obtained in phosphate-water solution due to the acidogenesis of anaerobic fermentation. Additionally, MOF-808-(25) improved the hydrolysis of proteins through non-biological catalysis. These findings depict a promising vision for phosphorus recovery by MOF-808-(25).

Microwave‐assisted hydrothermal green synthesis of selenium nanoparticles incorporated with hyaluronic acid methacrylate/gelatin methacrylate hydrogels for wound healing applications

AbstractWound healing is a topic of significant interest in current times, owing to the escalating incidence of chronic diseases associated with impaired healing, as well as the growing number of elderly individuals within the population. Amongst the various approaches for fabrication of wound healing dressings, the utilization of selenium‐based nanoparticles has garnered considerable attention due to selenium's numerous advantages, including antioxidant, antiviral, antibacterial, and antifungal activities. With this perspective, we focused on the fabrication and characterization of hydrogels incorporated with selenium nanoparticles (SeNPs). In this work, we have developed a microwave‐assisted hydrothermal synthesis strategy for synthesis of the SeNPs that employ non‐toxic precursors, thereby reducing the risk of environmental toxicity and providing a cost‐effective alternative to conventional chemical and hydrothermal methods. Subsequently, we have successfully incorporated SeNPs into hyaluronic acid methacrylate/gelatin methacrylate‐based hydrogels. Hyaluronic acid and gelatin are selected to support the healing process further, and these polymers are methacrylated in order to further control mechanical properties of the hydrogel and improve the stability of the dressing. The nanoparticles and the nanoparticle‐incorporated hydrogels were characterized by various techniques including Fourier transform infrared spectroscopy, UV–Vis spectroscopy, scanning electron microscopy, and dynamic light scattering instruments. Mechanical behaviors, swelling and degradation properties of the dressings were evaluated. Afterwards, we have conducted cell culture studies with SeNPs‐loaded hydrogels to determine the efficacy of SeNPs in wound healing. According to experimental findings, in vitro scratch assay suggests that a hydrogel dressing containing SeNPs (HG‐SeNp2) support the cell migration more compared to other samples incorporated with nanoparticles and to the control study at 24 h, and the wound closure percentage was found to be statistically significant compared with the control study. This dressing hold promise as effective wound dressings that can facilitate and expedite the process of wound healing.

Preparation of hydroxyapatite (HAP) from waste eggshells for enhancing the granulation and treatment performance of aerobic granular sludge: Enhancement effects and mechanism insights

Hydroxyapatite (HAP), an inorganic mineral that is generated in situ within the core of aerobic granular sludge (AGS), plays a pivotal role in both the granulation process and system stability. Due to the slow precipitation rate of HAP, waste eggshells were utilized as a readily available source for preparing HAP by using the conventional hydrothermal (C-HAP) and microwave hydrothermal (M-HAP) methods. Subsequently, the prepared HAP was employed to promote AGS formation. Results showed that the prepared HAP exhibits superior morphology, crystallinity, functional groups, and specific surface area compared to the commercial grade HAP, whereby M-HAP outperforms C-HAP for functional groups and specific surface area. The addition of 0.5 g/L HAP facilitated the granulation process (within 20 days), leading to the development of structurally compact AGS, which was attributed to the microbial attachment onto HAP particles. Moreover, the presence of HAP greatly improved the nutrient removal efficiency (80.8 % of TN and 82.4 % of PO43−-P), most likely due to the enrichment of denitrifying and phosphorus-accumulating microorganisms (e.g., Candidatus_Competibacter and Flavobacterium). Further analysis revealed that an increase in the relative abundance of denitrification-related genes (e.g., narG and nirK) was responsible for the intrinsic mechanism behind the enhanced nitrogen removal, while phosphorus removal occurred through biomineralization and abiotic precipitation pathways. Overall, the present study highlights the potential of utilizing waste eggshells to enhance AGS systems for wastewater treatment, thus realizing a circular economy approach.