Probing the photocatalytic competency of hydroxyapatite synthesized by solid state and wet chemical precipitation method

Crystal structure modification of nano-hydroxyapatite using organic modifiers and hydrothermal technique

Hydroxyapatite (HAp) synthesis was achieved through a hydrothermal method involving orthophosphoric acid and calcium hydroxide. Different organic modifiers such as urea, naphthalene, and palmitic acid were applied in the reaction system to modify the crystallite size along with the morphology of HAp. The synthesized HAp was validated via X-ray diffraction (XRD) data, Fourier Transform Infrared (FTIR) spectra, Field Emission Scanning Electron Microscopy (FESEM) image, and optical bandgap energy (<6 eV) was determined through UV-vis spectrophotometry. Apart from that, different techniques such as Scherrer's method, Halder-Wagner model, Williamson-Hall method, size-strain plot, as well as Sahadat-Scherrrer's models were applied for calculating the crystal domain size, and some models also incorporated energy density, strain, and stress. The synthesized HAp has a crystal structure that falls within the permissible range of <100 nm, as established by analyzing the XRD data using established models. Nevertheless, the values for strain (from -0.0006 to 0.0062), stress (from -30 902 to 36 940 N m-2), as well as energy density (from 4 × 10-14 to 113.72 J m-3) were likewise computed for the synthesized HAp. The texture co-efficient analysis reveals that doped HAp is grown in the (202) and (112) planes, palmitic acid_HAp in (002), (112), and (202) planes, while all the synthesized HAp (pure HAp, urea, naphthalene) is grown in the (002) and (112) planes. Rietveld refinement was also performed to estimate the quantative phase percentage from XRD data.

Different solvents and organic modifiers for the control of crystallographic parameters in nano-crystallite hydroxyapatite for amplification of photocatalytic activity

In this research, HAp nanocrystals were synthesized using conventional wet chemical precipitation methods using various organic modifiers, including urea, palmitic acid, and naphthalene. Ethanol and isopropyl alcohol (IPA) were used as solvents in this process. Different characterization techniques, namely X-ray diffraction (XRD), scanning electron microscopy (SEM), and UV-vis absorption spectroscopy, were employed to ascertain the formation of HAp nanocrystals. Numerous structural parameters, including lattice parameters, unit cell size, volume of the unit cell, specific surface area, degree of crystallinity, dislocation density, macrostrain, and crystallinity index, were assessed using XRD data. The linear straight-line method of Scherrer's equation, Monshi-Scherrer's method, the Williamson-Hall method, the size-strain plot method, the Halder-Wagner method, and Sahadat-Scherrer's model were applied to compute the crystallite size of the synthesized HAp samples. All the synthesized HAp has crystalline structures within the permissible range of 1-150 nm which were estimated from the XRD data using the mentioned models. However, the values for strain (from -3 × 10-4 to 6.4 × 10-3), strain (from -9.599 × 104 to 7 × 1010 N m-2), and energy density (from -11 × 1011 to 2 × 107 J m-3) were also calculated for the synthesized samples. In addition, the optical band gap energy of the synthesized HAp was computed (5.89 to 6.19 eV). The synthesis media have a control on the crystallographic planes, e.g. in the case of the ethanol medium, the (110) plane exhibited significant intensity (which could potentially serve as a driving force for enhancing photocatalytic activity). The use of 100% ethanol HAp yields the most favorable outcome regarding both the degradation percentage (91.79%) and degradation capacity (7%) for the Congo red dye.

Amplification of photocatalytic degradation of antibiotics (amoxicillin, ciprofloxacin) by sodium doping in nano-crystallite hydroxyapatite

In this research, we explain the production of sodium-doped hydroxyapatite (Na_HAp) via wet chemical precipitation, followed by crystal modification. To enhance its photocatalytic activity different % of (0.25, 0.5, 1, and 2) sodium doped into HAp crystal. It has been demonstrated that doping is an effective method for modifying the properties of nanomaterials, such as their optical performance and chemical reactivity. Several instrumental approaches were used to characterize this newly synthesized sodium-doped HAp (Na_HAp), e.g. scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), and UV-vis spectrometry were used to analyze the morphology, elemental composition, crystal structure, and optical bandgap, respectively. Under sunlight irradiation, the new Na_HAp photocatalyst was put to use in the process of degrading pharmaceutical pollutants such as antibiotics (amoxicillin and ciprofloxacin). It was found that using a 0.1 g dose of 1% Na_HAp under specified conditions, such as a pH of 7 and 120 minutes of sunlight irradiation, resulted in degradation percentages of 60% and 41.59% for amoxicillin and ciprofloxacin, respectively. Different radical scavengers were utilized to determine the reaction mechanism for the photochemical degradation of antibiotics. Additionally, the ability to be reused and the stability of 1% Na_HAp, a newly developed photocatalyst, were assessed. Therefore, this research adds to our understanding of how to optimize redox capacity for the rapid breakdown of a variety of antibiotics when exposed to sunlight.

Synthesis of different types of nano-hydroxyapatites for efficient photocatalytic degradation of textile dye (Congo red): a crystallographic characterization

The textile industry, a vital economic force in developing nations, faces significant challenges including the release of undesired dye effluents, posing potential health and environmental risks which need to be minimized with the aid of sustainable materials. This study focuses on the photocatalytic potential of hydroxyapatite together with different dopants like titanium-di-oxide (TiO2) and zinc oxide (ZnO). Here, we synthesized hydroxyapatite (HAp) using different calcium sources (calcium hydroxide, calcium carbonate) and phosphorous sources (phosphoric acid, diammonium hydrogen phosphate) precursors through a wet chemical precipitation technique. Pure and doped HAp were characterized via different technologies, which consist of X-ray diffraction (XRD), Fourier Transform Infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), as well as UV-vis spectroscopy. The effectiveness of the synthesized photocatalyst was evaluated by its interactivity with synthetic azo dyes (Congo red). The photodegradation of Ca(OH)2_HAp, CaCO3_HAp, ZnO-doped HAp as well as TiO2-doped HAp, were obtained as 89%, 91%, 86%, and 91%, respectively. Furthermore, at neutral pH, TiO2-doped HAp shows the highest degradation (86%), whereas ZnO-doped HAp possesses the lowest degradation (73%). Additionally, various XRD models (Monshi-Scherrer's, Williamson-Hall, and Halder-Wagner methods) were employed to study crystallite dimension.

Synthesis of nano-crystallite hydroxyapatites in different media and a comparative study for estimation of crystallite size using Scherrer method, Halder-Wagner method size-strain plot, and Williamson-Hall model

Hydroxyapatite (HAp) [Ca10(PO4)6(OH)2] is remarkably similar to the hard tissue of the human body and the uses of this material in various fields in addition to the medical sector are increasing day by day. In this research, mustered oil, soybean oil, as well as coconut oil were employed as liquid media for synthesizing nanocrystalline HAp using a wet chemical precipitation approach. The X-ray diffraction (XRD) study verified the crystalline phase of the HAp in all the indicated media and discovered similarities with the standard database. Several prominent models such as the Scherrer's Method (SM), Halder-Wagner Method (HWM), linear straight-line method (LSLM), Williamson-Hall Method (W-M), Monshi Scherrer Method (MSM), Size-Strain Plot Method (SSPM), Sahadat-Scherrer Method (S-S) were applied for the determination of crystallite size. The stress, strain, and energy density were also computed from the above models. All the models, without the Linear straight-line technique of Scherrer's equation, resulted in an appropriate value of crystallite size for synthesized products. The calculated crystallite sizes were 6.5 nm for HAp in master oil using Halder-Wagner Method, and 143 nm for HAp in coconut oil using the Scherrer equation which were the lowest and the largest, respectively.

Photocatalyst of manganese ferrite and reduced graphene oxide supported on activated carbon from cow bone for wastewater treatment

The present research aimed to evaluate the photocatalytic activity of manganese ferrite (M) and reduced graphene oxide (G) supported on pulverized activated carbon from cow bone waste (PAC-MG). PAC-MG was characterized by different instrumental techniques. The efficiency of PAC-MG was evaluated using solar irradiation under different conditions of photocatalyst concentration, H2O2 concentration, and pH ranges for the discoloration of methylene blue dye (MB). The synergy between the nanomaterials potentiated the photocatalytic activity, reaching 85.5% of MB discoloration when using 0.25 g L-1 of catalyst at neutral pH with no oxidant needed. Furthermore, PAC-MG demonstrated excellent stability in 6 consecutive cycles. Finally, it is expected that the present study can add value to industrial waste and contribute to the development of novel water and wastewater treatment methods, ensuring water quality for human consumption and the environment.

Development of Hydroxyapatite Coatings for Orthopaedic Implants from Colloidal Solutions: Part 1-Effect of Solution Concentration and Deposition Kinetics

This study introduces and explores the use of supersaturated solutions of calcium and phosphate ions to generate well-defined hydroxyapatite coatings for orthopaedic implants. The deposition of hydroxyapatite is conducted via several solutions of metastable precursors that precipitate insoluble hydroxyapatite minerals at a substrate-solution interface. Solutions of this nature are intrinsically unstable, but this paper outlines process windows in terms of time, temperature, concentration and pH in which coating deposition is controlled via the stop/go reaction. To understand the kinetics of the deposition process, comparisons based on ionic strength, particle size, electron imaging, elemental analyses and mass of the formed coating for various deposition solutions are carried out. This comprehensive dataset enables the measurement of deposition kinetics and identification of an optimum solution and its reaction mechanism. This study has established stable and reproducible process windows, which are precisely controlled, leading to the successful formation of desired hydroxyapatite films. The data demonstrate that this process is a promising and highly repeatable method for forming hydroxyapatites with desirable thickness, morphology and chemical composition at low temperatures and low capital cost compared to the existing techniques.

Nano-crystallite bones of Oreochromis niloticus and Katsuwonus pelamis for the photocatalytic degradation of Congo red dye

The bones of two fish species, Oreochromis niloticus and Katsuwonus pelamis, were chosen in this research for evaluating their photocatalytic efficacy under solar radiation. The fish bones were isolated and conditioned before analyzing crystallographic parameters. The samples were characterized by using different instrumental techniques such as Fourier Transform Infrared (FTIR), X-ray diffraction (XRD), Energy Dispersive X-ray (EDX), Field Emission Scanning Electronic Microscopy (FESEM), and optical bandgap. From the XRD data, various types of crystallographic information such as crystallite size, microstrain, lattice parameters, dislocation density, degree of crystallinity, crystallinity index, Hydroxylapatite (HAp), the volume fraction of β-TCP, β-Tricalcium phosphate (β-TCP) percentage, and specific surface area were evaluated. Different model equations such as the Sahadat-Scherrer model, Linear Straight-line model, Monshi-Scherrer's method, and Williamson-Hall plot were employed to justify the nano-crystallite size. The photocatalytic efficacy of the two types of samples was explored by changing the catalyst concentration, dye concentration, interaction time, pH of the solution, etc. under solar irradiation.

Biodiesel production from date seed oil using hydroxyapatite-derived catalyst from waste camel bone

Biodiesel is considered to be more friendly to the environment than petroleum-based fuels, cheaper and capable for producing greener energy which contributed positively in boosting bio-economy. A new non-edible feedstock utilized from date seed oil was analyzed for the synthesis of eco-friendly biodiesel using newly novel hydroxyapatite heterogeneous catalysts, obtaining from waste camel bones prepared from dried camel bone followed calcination under different temperature. This catalyst was characterized by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) and transmission electron microscopy (TEM). Results showed that hydroxyapatite catalyst pore size reduced with increasing the calcination temperature. Optimize biodiesel yield (89 wt%) was achieved through the process of transesterification with optimum reaction conditions of 4 wt% catalyst, oil to ethanol molar ratio of 1:7 and temperature 75 °C for 3 h reaction time. The production of FAME was confirmed by using gas chromatography-mass spectroscopy (GC-MS). Fuel properties of fatty acid ethyl ester complied with ASTM D 6751 which indicated that it would be an appropriate alternative form of fuel. As a result, using biodiesel made from waste and untamed resources to develop and implement a more sustainable and environmentally friendly energy strategy is commendable. The acceptance and implementation of the green energy method may result in favorable environmental effects, which in turn may lead to better societal and economic growth for biodiesel industry at a larger scale.

Enhancement of photocatalytic efficacy by exploiting copper doping in nano-hydroxyapatite for degradation of Congo red dye

This research deals with the photocatalytic activity of hydroxyapatite and the improvement of efficiency by doping various percentages of copper; the catalysts were synthesized by the wet-chemical method. Pure and copper-doped photocatalysts were characterized by several techniques including X-ray diffraction (XRD), Fourier Transform Infrared (FTIR) spectroscopy, Raman spectroscopy, scanning electron microscopy (SEM), thermogravimetric analysis (TGA), dynamic scanning calorimetry (DSC), and UV-Vis spectroscopy. The competency of pure and copper-doped hydroxyapatite as photocatalysts was assessed by their interaction with Congo red dye. The crystallographic parameters of the catalysts were also estimated by employing the XRD technique, and a relationship was established between the calculated parameters and photocatalytic performance. Crystallite size was calculated from various model equations, which revealed an acceptable crystallite size of 42-68 nm. Copper doping in hydroxyapatite impressively augmented the photocatalytic efficacy, for example 99% dye was degraded upon 0.63% Cu-doping compared to 75% for the pure HAp, which was exemplified not only by the reaction rate but also by the quantum yield. The degradation percentages changed with time but became fixed at 200 min. The molar extinction coefficient was estimated by employing the Beer-Lambert law and further utilized to compute the photonic efficiency of the catalysts. In the study of the photochemical reaction, a simplified reaction process was proposed, and the potentials of the conduction band and valence band were assessed, which influenced the activity. The doping of Cu in crystalline hydroxyapatite will enhance the photocatalytic activity towards Congo red dye under all experimental conditions.

Advances of Hydroxyapatite Hybrid Organic Composite Used as Drug or Protein Carriers for Biomedical Applications: A Review

Hydroxyapatite (HA), especially in the form of HA nanoparticles (HANPs), has excellent bioactivity, biodegradability, and osteoconductivity and therefore has been widely used as a template or additives for drug delivery in clinical applications, such as dentistry and orthopedic repair. Due to the atomically anisotropic distribution on the preferred growth of HA crystals, especially the nanoscale rod-/whisker-like morphology, HA can generally be a good candidate for carrying a variety of substances. HA is biocompatible and suitable for medical applications, but most drugs carried by HANPs have an initial burst release. In the adsorption mechanism of HA as a carrier, specific surface area, pore size, and porosity are important factors that mainly affect the adsorption and release amounts. At present, many studies have developed HA as a drug carrier with targeted effect, porous structure, and high porosity. This review mainly discusses the influence of HA structures as a carrier on the adsorption and release of active molecules. It then focuses on the benefits and effects of different types of polymer-HA composites to re-examine the proteins/drugs carry and release behavior and related potential clinical applications. This literature survey can be divided into three main parts: 1. interaction and adsorption mechanism of HA and drugs; 2. advantages and application fields of HA/organic composites; 3. loading and drug release behavior of multifunctional HA composites in different environments. This work also presents the latest development and future prospects of HA as a drug carrier.