Wet Precipitation Process Research Articles

Aspen plus-based techno-economic assessment of a solar-driven calcium looping CO2 capture system integrated with CaO sorbent reactivation

Given the gradual nature of the energy transition, retrofitting coal-fired power plants with carbon capture technology is crucial. The calcium looping (CaL) process is a promising solution, with challenges like absorbent deactivation and reduced thermal efficiency mitigated by absorbent reactivation and heat recovery systems. This study evaluated the techno-economic feasibility of integrating a novel wet extraction and precipitation process for absorbent reactivation within a solar-assisted CaL system, alongside an existing coal power plant. The process incorporated a secondary steam cycle and an ammonia absorption chiller for enhanced heat recovery and district cooling. The integrated project could increase daily power generation by 50% and reduce CO2 emissions from 820.4 g/kWh to 54.5 g/kWh. Over its lifespan, the reactivation facility could reduce limestone extraction by 21 Mt with 90% capture efficiency. With a levelized cost of electricity (LCOE) of 116.1 €/MWh and breakeven electricity selling price (BESP) of 56.6 €/MWh, the system demonstrated promising commercial viability, with the reactor and concentrated solar heating (CSH) system making up over 60% of investment costs. CSH cost and solar abundance were identified as key factors, indicating potential feasibility even in higher latitude regions. At CO2 revenues of 150 €/t, a stand-alone capture project can break even based solely on CO2 sales, demonstrating its potential for expansion to other areas. A case study highlighted the benefits of integrating absorbent reactivation and an ammonia absorption chiller, improving both economics and carbon capture efficiency. The study also confirmed the viability of solar-assisted projects in high-latitude regions, with optimistic future CO2 revenues and advancements in carbon capture technology enhancing feasibility.

Effect of temperature on crystallite size of hydroxyapatite powders obtained by wet precipitation process

In this investigation, HAp powders were synthesized using the wet chemical precipitation technique. The temperature of the heat treatment (80 °C, 120 °C, and 160 °C) and the addition of glutamic acid were the considered process parameters. After the reaction between the precursors calcium nitrate [Ca(NO3)2] and ammonium phosphate [(NH4)H2PO4], decantation of the residue, drying, and finally, heat treatment of the residue were done sequentially. X-ray diffraction (XRD) analysis, scanning electron microscope (SEM) observations, and X-ray fluorescence (XRF) analysis were carried out to characterize the synthesized HAp powders. It was found that at a high heat treatment temperature plus the addition of glutamic acid are suitable process parameters to acquire uniform HAp powders with plate morphology and fibers with an average particle size of ∼100–200 µm. The Ca/P ratio obtained was like the hydroxyapatite present in the bones in the order of 1.72. This situation can be indicated as an essential advantage in the biocompatibility of the synthesized material. The use of glutamic acid suggests crystal growth in a preferential direction as reported in our previous work. The manufacture of hydroxyapatite, especially in powder, is of great interest in developing additive manufacturing systems for the biomedical market.

Synthesis and Characterization of Hydroxyapatite from Duck Eggshell by Wet Precipitation Process

Hydroxyapatite (HAp, Ca10(PO4)6(OH)2) is the most stable form of calcium phosphate and widely used in various medical applications, mainly in orthopedics and dentistry due to its close similarities with the inorganic mineral component of bone and teeth. This study aims to synthesize hydroxyapatite from duck eggshell using the precipitation method. The duck eggshell was calcined, hydrated (slaking) and underwent carbonation to form Precipitated Calcium Carbonate (PCC). Afterwards, (NH4)2HPO4 was added to produce HAp by varying the molar ratio of Ca/P by 1.67, 1.77 and 1.87 and stirring speed by 200, 250, 300rpm under basic condition (pH 10 – 11). The best results were obtained at a molar ratio of 1.77 with 200rpm stirring speed. Furthermore, the X-ray Diffraction (XRD) analysis showed that its crystals were hexagonal with sizes of 23.062nm, in the absence of other crystalline phases. Therefore, the hydroxyapatite was obtained in the agglomerates form with a specific surface area of ??55.929m2/g.

Synthesis and Characterization of Hydroxyapatite- (HAP-) Clay Composites and Adsorption Studies on Methylene Blue for Water Treatment

Dyes used by the textile, tannery, and food industries tend to pollute water bodies and must be removed to get clean water. Hydroxyapatite (HAP) was synthesized from eggshells using the wet precipitation process. The as-synthesized HAP was characterized using Fourier Transform Infrared (FTIR) and X-ray powder diffraction (XRD). The synthesized HAP was mixed with three different clays: halloysite (HNT), kaolinite (KAO), and bentonite (BENT). The removal efficiency values of methylene blue (MB) from the data showed that HAP-BENT adsorbents had higher values, followed by HAP-HNT and then HAP-KAO adsorbents. The combined masses of 24 mg, 34.5 mg, and 33 mg (representing 20%, 15%, and 10% of HAP-BENT mass) had average adsorption capacity values of 20.7 mg/g, 17.2 mg/g, and 17.9 mg/g, respectively. For each mass percentage, the adsorption capacity values were found to decrease with adsorbent dosage. The HAP-BENT composites had removal efficiency values of 98.4, 91.9%, and 91.9%, respectively. Adsorption data for the HAP-BENT adsorbents were found to be well described by the Langmuir isotherm model and pseudo-second-order kinetic model. The effect of temperature on adsorption capacity was evaluated and thermodynamical modeling was undertaken. The thermodynamical modeling predicts that based on the value of the change in enthalpy and Gibbs free energy the process was exothermic and spontaneous. This work confirms the potential of HAP-clay composites in removing MB from water.

Super fine cerium hydroxide abrasives for SiO2 film chemical mechanical planarization performing scratch free

Face-centered-cubic crystallized super-fine (~ 2 nm in size) wet-ceria-abrasives are synthesized using a novel wet precipitation process that comprises a Ce4+ precursor, C3H4N2 catalyst, and NaOH titrant for a synthesized termination process at temperature of at temperature of 25 °C. This process overcomes the limitations of chemical–mechanical-planarization (CMP)-induced scratches from conventional dry ceria abrasives with irregular surfaces or wet ceria abrasives with crystalline facets in nanoscale semiconductor devices. The chemical composition of super-fine wet ceria abrasives depends on the synthesis termination pH, that is, Ce(OH)4 abrasives at a pH of 4.0–5.0 and a mixture of CeO2 and Ce(OH)4 abrasives at a pH of 5.5–6.5. The Ce(OH)4 abrasives demonstrate better abrasive stability in the SiO2-film CMP slurry than the CeO2 abrasives and produce a minimum abrasive zeta potential (~ 12 mV) and a minimum secondary abrasive size (~ 130 nm) at the synthesis termination pH of 5.0. Additionally, the abrasive stability of the SiO2-film CMP slurry that includes super-fine wet ceria abrasives is notably sensitive to the CMP slurry pH; the best abrasive stability (i.e., a minimum secondary abrasive size of ~ 130 nm) is observed at a specific pH (6.0). As a result, a maximum SiO2-film polishing rate (~ 524 nm/min) is achieved at pH 6.0, and the surface is free of stick-and-slip type scratches.

Synthesis of Anhydrous Dicalcium Phosphate for Precursor of Natural Ceramic Apatite Material

Dicalcium phosphate is one of the apatite materials used for precursors to synthesize other apatite materials such as tricalcium phosphate, tetracalcium phosphate, and hydroxyapatite. Apatite materials are widely used in the medical field and pharmaceutical industry. This study aims to prepare dicalcium phosphate from natural limestone as a precursor for apatite with an easy-to-apply method for industrial scale. Wet precipitation process was performed to prepare dicalcium phosphate from phosphoric acid and slaked lime or calcium hydroxide with reaction temperature control at around 60⁰C and at pH of 3-4, then drying is carried out at about 180⁰C. The product is characterized for its mineral content by XRD and EDX. Semi-quantitative calculation of the synthesized material contains more than 90% dicalcium phosphate andhydrous, the rest is other apatite minerals. It can be used as a precursor for apatite production.

Analysis of antibacterial activity and cytotoxicity of silver oxide doped hydroxyapatite exposed to DC glow discharge plasma

The present work investigated the possibility of enhancing hydroxyapatite (HAp) bioactivity by substituting silver oxide. Ag2O-HAp nanoparticles were synthesized by using the wet precipitation process with exposure to DC glow discharge non thermal plasma. The phase purity, elemental composition and morphology were analyzed by XRD, FTIR, SEM and EDX. MTT assay for Silver oxide doped hydroxyapatite (Ag2O HAP) nanopowders (NPs) have been carried out for MCF-7 breast cancer cell line and the cyototoxicity effect were analysed. The biocompatibility of the synthesized silver oxide doped HAp proves it as promising candidate for upcoming biomedical applications.

Plasmon induced enhanced photocatalytic activity of gold loaded hydroxyapatite nanoparticles for methylene blue degradation under visible light

A facile surfactant free wet-precipitation process was employed to prepare hydroxyapatite (HAp) nanoparticles.

Synthesis of high surface area, mesoporous MgO nanosheets with excellent adsorption capability for Ni(II) via a distillation treating

Hexagonal mesoporous MgO nanosheets with a side length of 250nm and specific surface area of 181.692m2/g were fabricated by a three-step process. Firstly, MgO powders were obtained by sintered Mg5(OH)2(CO3)4⋅4H2O, which was synthesized by a wet precipitation process using ammonium hydrogen carbonate as precipitants. Secondly, the above-MgO were distilled 2h in a three-necked bottle with condenser device. Lastly, we annealed the distilled-MgO at 500–800°C to form mesoporous MgO nanosheets. We found the pore size distribution and the thicknesses of nanosheets were determined by the distillation process in step 2 and annealed temperature in step 3. By optimizing the experimental parameters, the mesoporous dis-MgO annealed at 600°C displayed uniform hexagonal structure with the largest pore volume (0.875cm3/g) and highest BET surface area (181.692m2/g), as well as the maximum adsorption capability of 1684.25mg/g for Ni(II).

Adsorption behavior of Zn(II) ions on synthetic hydroxyapatite

The adsorption of Zn2+ on synthetic hydroxyapatite was investigated using a batch method and a radiotracer technique. The commercial hydroxyapatite and hydroxyapatite of high crystallinity with Ca/P ratio of 1.563:1.688 prepared by a wet precipitation process were used in this study. The adsorption of zinc on hydroxyapatite was pH independent ranging from 4.5 to 6.5 as a result of buffering properties of hydroxyapatite. The adsorption of zinc was rapid and the percentage of Zn adsorption on both samples of hydroxyapatite was >96% during the first 30 min of the contact time. The experimental data for adsorption of zinc have been interpreted in terms of Langmuir isotherm and the values of maximum adsorption capacity of zinc on a commercial hydroxyapatite and hydroxyapatite prepared by wet precipitation process were calculated to be 0.437 and 0.605 mmol g−1, respectively. The competition effect of Fe2+ towards Zn2+ adsorption was stronger than that of Ca2+, Mg2+, and Sr2+ ions. The ability of the bivalent cations to depress the adsorption of zinc on hydroxyapatite was in the following order: Fe2+ > Ca2+ > Sr2+ ≈ Mg2+.

Phosphating of Calcium Carbonate for Obtaining Hydroxyapatite from the Ostrich Egg Shell

The Hydroxyapatite (HA), the major component of the inorganic portion of bones, may be obtained from different sources for use as biomaterial in the reconstruction of critical bone defects. Among these resources, the eggshell appears as a promising alternative since it is a waste material which may be reused as a source of calcium carbonate after adequate treatment, giving rise to mineral hydroxyapatite. After morphological and physicochemical adjustments allowing its standardization and utilization, hydroxyapatite (HA) may turn into a potentially useful biomaterial for different experimental purposes. This paper aims to present a viable method for obtaining a hydroxyapatite from Ostrich eggshell by wet precipitation process. This phosphating technique with emphasis on the issue of sustainable reuse of disposable materials allows the production of a synthetic crystalline material with characteristics similar to those of bone and tooth. The structural characterization was performed by X-Ray diffraction and scanning electron microscopy with field emission gun and energy dispersive X-ray in the Military Institute of Engineering.

Characterization, antibacterial and in vitro compatibility of zinc–silver doped hydroxyapatite nanoparticles prepared through microwave synthesis

We investigated the possibility of enhancing hydroxyapatite (HA) bioactivity by co-substituting it with zinc and silver. Zn–Ag–HA nanoparticles were synthesized by using the microwave-assisted wet precipitation process, and their phase purity, elemental composition, morphology, and particle size were analyzed by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDX). FTIR, XRD, and EDX results showed the characteristic peaks of the Zn–Ag–HA structure, while SEM results demonstrated that the nanoparticles were of spherical shape with a particle size of 70–102nm. Antibacterial tests of the nanoparticles revealed their antibacterial activity against Staphylococcus aureus and Escherichia coli. By using simulated body fluid (SBF), an apatite layer formation was observed at 28 days. In vitro cell adhesion assay confirmed the cell attachment of normal human osteoblast (NHOst) cells to the disc surface. MTT [(3(4, 5-dimethylthiazol-2-yl)-2, 5 diphenyltetrazolium bromide] assay indicated that the cells were viable, and the cells proliferated faster on the disks than on the control surface due to the presence of metal ions. In conclusion, the novel Zn–Ag–HA nanoparticles were found to be compatible with in vitro experiments and having potential antibacterial properties. Therefore these nanoparticles could be a promising candidate for future biomedical applications.

Greener photocatalysts: Hydroxyapatite derived from waste mussel shells for the photocatalytic degradation of a model azo dye wastewater

This paper demonstrates for the first time the feasibility of utilising waste mussel shells for the synthesis of hydroxyapatite, Ca10(PO4)6(OH)2 (denoted as HAP) to be used as a greener, renewable photocatalyst for recalcitrant wastewater remediation. HAP was synthesised from Perna canaliculus (green-lipped mussel) shells using a novel pyrolysis–wet slurry precipitation process. The physicochemical properties of the HAP were characterised using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM). The HAP produced was of comparable quality to commercial (Sulzer Metco) HAP. The synthesised HAP had good photocatalytic activity, whereby methylene blue (a model textile wastewater compound) and its azo dye breakdown products were degraded with an initial rate of 2.5×10−8molL−1min−1. The overall azo dye degradation was nearly 54% within 6h and 62% within 24h in an oxygen saturated feed in a batch reactor using a HAP concentration of 2.0g/L, methylene blue concentration of 5mgL−1, UV irradiation wavelength of 254nm and a stirring speed of 300rpm. The kinetics were well described by three first order reactions in series, reflecting the reaction pathway from methylene blue to azo dye intermediates, then to smaller more highly oxidised intermediates and finally degradation of the recalcitrants. The final two steps of the reaction had significantly slower rates than the initial step (rates constants of 6.2×10−3min−1, 1.2×10−3min−1 and approximately (due to limited data points) 1.6×10−4min−1 for the first, second and third step respectively), which tie in with this mechanism, however it could also indicate that the reaction is either product inhibited and/or affected by catalyst deactivation. FTIR analysis of the post-reaction HAP revealed surface PO43− group loss. Since there is good photocatalytic activity with oxygen in limited and excess supply during the photoreaction, this indicates the possibility of lattice oxygen participation in the photocatalytic reaction, which needs to be characterised more fully. However, overall, these results indicate that the HAP derived from the mussel shells is a promising greener, renewable photocatalyst for the photocatalytic degradation of wastewater components.

Resorbable Tricalcium Phosphates for Bone Tissue Engineering: Influence of SrO Doping

Tricalcium Phosphate (TCP) was doped with 0.5, 2.0, and 5.0 mol% Strontium Oxide (SrO) through the wet precipitation process to investigate the influence of SrO on the biological and mechanical properties of TCP. XRD results showed that SrO doping did not change the phase stability of the β‐phase of TCP during sintering at 1120°C. The apparent density of TCP increased from 95.1 ± 2.5% to 99.4 ± 0.5% with the addition of 5.0 mol% SrO doping. SrO doping also increased the compressive strength of pure β‐TCP from 121.1 ± 21.4 MPa to 185.9 ± 16.7 MPa with 5 mol% SrO addition. Initially, the addition of 0.5 and 2.0 mol% SrO had a statistically insignificant impact on the as‐processed samples' compressive strength. When the samples were immersed in a simulated body fluid for 12 weeks, the addition of SrO improved the compressive strength from 109.4 ± 22.9 MPa for pure TCP to 208.8 ± 34.6 MPa with 5.0 mol% SrO addition. An improvement in hFOB cell attachment and proliferation was observed for all dopant concentrations using field emission scanning electron microscope (FE‐SEM) imaging and MTT assay studies, indicating excellent biocompatibility of all the samples. 2.0 mol% SrO doping showed the best cell differentiation and proliferation results. It was shown that SrO simultaneously improved mechanical properties of TCP such as compressive strength as well as biological properties via enhanced cell attachment and proliferation.

Adsorption of nickel on synthetic hydroxyapatite from aqueous solutions

The sorption of nickel on synthetic hydroxyapatite was investigated using a batch method and radiotracer technique. The hydroxyapatite samples used in experiments were a commercial hydroxyapatite and hydroxyapatite of high crystallinity with Ca/P ratio of 1.563 and 1.688, respectively, prepared by a wet precipitation process. The sorption of nickel on hydroxyapatite was pH independent ranging from 4.5 to 6.5 as a result of buffering properties of hydroxyapatite. The adsorption of nickel was rapid and the percentage of Ni sorption on both samples of hydroxyapatite was >98 % during the first 15–30 min of the contact time for initial Ni2+ concentration of 1 × 10−4 mol dm−3. The experimental data for sorption of nickel have been interpreted in the term of Langmuir isotherm and the value of maximum sorption capacity of nickel on a commercial hydroxyapatite and hydroxyapatite prepared by wet precipitation process was calculated to be 0.184 and 0.247 mmol g−1, respectively. The sorption of Ni2+ ions was performed by ion-exchange with Ca2+ cations on the crystal surface of hydroxyapatite under experimental conditions. The competition effect of Co2+ and Fe2+ towards Ni2+ sorption was stronger than that of Ca2+ ions. NH4 + ions have no apparent effect on nickel sorption.

Study of sorption processes of copper on synthetic hydroxyapatite

The sorption of copper on synthetic hydroxyapatite was investigated using a batch method and radiotracer technique. The hydroxyapatite sample prepared by a wet precipitation process was of high crystallinity with Ca/P ratio of 1.688. The sorption of copper on hydroxyapatite was pH independent ranging from 4 to 6 as a result of buffering properties of hydroxyapatite. The adsorption of copper was rapid and the percentage of Cu sorption was >98% during the first 15–30 min of the contact time. The experimental data for sorption of copper have been interpreted in the term of Langmuir isotherm. The sorption of Cu2+ ions was performed by ion-exchange with Ca2+ cations on the crystal surface of hydroxyapatite under experimental conditions. The competition effect of Zn2+, Fe2+ and Pb2+ towards Cu2+ sorption was stronger than that of Co2+, Ni2+ and Ca2+ ions. The ability of the bivalent cations to depress the sorption of copper on hydroxyapatite was in the following order Pb2+ > Fe2+ > Zn2+ > Co2+ ≈ Ni2+.

Processing of natural resourced hydroxyapatite from eggshell waste by wet precipitation method

In the present paper, synthesis of hydroxyapatite (HAp) powder from eggshell waste is produced through wet precipitation process at 50–55°C. The thoroughly washed and dried eggshell powder is treated with dilute nitric acid followed by diammonium hydrogen phosphate under controlled reaction conditions such as pH, temperature, stirring time, etc. to obtain white HAp precipitate. The formation of the HAp phase and its thermal stability were identified through thermogravimetric/differential thermal analysis, Fourier transform infrared spectroscopy and X‐ray diffraction studies at different calcined temperatures. The dried powder at 90–100°C was wet ball milled for several hours and compacted to cylindrical shapes at a lower pressure of 850 kg cm−2. The green compacts were sintered at different temperatures for 2 h in dry atmosphere. Average grain sizes of sintered samples are mostly in submicrometre range. The morphologies of the green as well as sintered compacts were observed by field emission scanning electron microscopy.

Phosphates nanoparticles doped with zinc and manganese for sunscreens

The crescent number of skin cancer worldwide gives impulse to the development of sunscreen that can both prevent skin cancer and also permit gradual tanning. In this work, the synthesis of hydroxyapatite and tricalcium phosphate nanocrystalline powders was investigated in order to obtain materials with optical properties and appropriate size for sunscreen. Pure, Zn 2+-doped and Mn 2+-doped hydroxyapatite (HAP) and tricalcium phosphate (β-TCP) were produced by the wet precipitation process using diammonium phosphate, calcium nitrate, ammonium hydroxide, zinc nitrate and manganese nitrate as reagents. The pure and doped HAP precipitates were calcined at 500 °C for 1 h, while the β-TCP (pure and doped) were calcined at 800 °C for 2 h. The powder samples were characterized by X-ray diffraction (XRD), energy dispersive X-ray fluorescence (EDX), atomic force microscopy (AFM) and ultraviolet (UV)–vis spectroscopy. XRD and EDX showed the formation of the expected materials (HAP and β-TCP) without toxic components. AFM micrographs showed aggregated ellipsoidal particles with dimensions smaller than 120 nm. Optical absorption spectra showed that the calcium phosphate produced in this work absorbs in the UV region. The obtained materials presented structural, morphological and optical properties that allow their use as the active centers in sunscreens.

Study of sorption processes of strontium on the synthetic hydroxyapatite

The sorption of strontium on synthetic hydroxyapatite was investigated using batch method and radiotracer technique. The hydroxyapatite samples were prepared by a wet precipitation process followed by calcination of calcium phosphate that precipitated from aqueous solution. Also, commercial hydroxyapatites were used. The sorption of strontium on hydroxyapatite depended on the method of preparation and it was pH independent ranging from 4 to 9 as a result of buffering properties of hydroxyapatite. The distribution coefficient Kd was significantly decreased with increasing concentration of Sr2+ and Ca2+ ions in solution with concentration above 1 × 10−3 mol dm−3. The percentage strontium sorption for commercial and by wet method prepared hydroxyapatite was in the range of 83–96%, while calcined hydroxyapatite was ranging from 10 to 30%. The experimental data for sorption of strontium have been interpreted in the term of Langmuir isotherm. The sorption of Sr2+ ions was performed by ion-exchange with Ca2+ cations on the crystal surface of hydroxyapatite. Although calcined hydroxyapatite is successfully used as biomaterial for hard tissues repair, it is not used for the treatment of liquid wastes.

Synthesis of porous, high surface area MgO microspheres

Porous MgO microspheres with nanocrystallites have been prepared by a wet precipitation process using ammonium hydrogen carbonate and ammonium hydroxide as precipitants. The as-precipitated powders are composed of crystalline Mg 5(OH) 2(CO 3) 4.4H 2O microspheres with porous and hollow microstructure and are decomposed and transformed to nanocrystalline cubic MgO after being calcined at 500 °C. The average crystallite size of MgO microspheres increases from 10 nm to 31.6 nm with increasing temperature from 500 °C to 1100 °C. The surface area of the MgO powder decreases from 90.7 m 2/g to 31.5 m 2/g with increasing temperature from 500 °C to 1100 °C.