Alkaline Precipitation Method Research Articles

Synthesis and characterization of iron oxides and their application as inorganic pigments in white paint

AbstractThe tones of iron oxide pigments range from yellow, red, brown and green to black. Iron oxide pigments are non‐toxic and have a nanometric particle size, which makes them ideal for use as pigments. The current study synthesised synthetic inorganic pigments based on iron oxides using the alkaline precipitation method. This approach to the synthesis of iron oxide pigments makes them less expensive for obtaining reproducible colours. Iron salts (iron (III) chloride, iron (III) nitrate, iron (II) sulphate [ferrous sulphate] and iron (III) sulphate) have been combined with alkaline solutions (sodium hydroxide, potassium hydroxide and ammonium hydroxide) to form coloured iron oxides, which are widely known as natural inorganic pigments. The 12 samples produced in four different colours (red, yellow, brown and black) were left in aqueous suspension and dispersed in commercial real white estate paint, to evaluate their behaviour as pigments. Structural characterisation (X‐ray diffractometry), composition (X‐ray fluorescence by dispersive energy), thermal analysis (i.e. thermogravimetric analysis and the differential thermal analysis) and spectroscopy (FTIR and photoacoustic), as well as colorimetry, were performed. The phases indexed by X‐ray diffractometry were goethite, haematite, magnetite and lepidocrocite. The inorganic pigments produced are compatible with natural inorganic pigments. They also showed dispersion compatibility in commercial white paint without changing the surface coating powder and are therefore an alternative to synthetic inorganic pigments.

Comparative study of zinc oxide nanoparticles synthesized through biogenic and chemical route with reference to antibacterial, antibiofilm and anticancer activities

The present focused on comparative study on synthesis of ZnO nanoparticles (ZnO NPs) using chemical method via alkaline precipitation method (ZnO(A) NPs) using NaOH and biogenic method using termite mound extract (ZnO(B) NPs). GC-MS analysis revealed that D-limonene present in termite mound extract might be responsible for the synthesis of ZnO(B) NPs. XRD patterns confirmed hexagonal crystalline structure of ZnO(A) and (B) NPs. Results of antibacterial activity illustrated that ZnO(B) NPs showed its potential against Pseudomonas aeruginosa, ESBL-1, ESBL-2 and EBSL-3. Antibiofilm studies revealed that ZnO(B) NPs exhibited optimum decline in MRSA biofilm formation than ZnO(A) NPs. In addition, ZnO(B) NPs showed potent cytotoxic effect against lung cancer cell lines A549 with IC50 of 35.16 ± 0.10 μg/mL in comparison with ZnO(A) NPs (IC50- 55.09 ± 0.30 μg/mL). Overall, the results revealed that biogenic synthesis of ZnO NPs ensures its biosafety level and enhanced biological activity when compared to chemical synthesis method.

The analgesic activities of total alkaloids of the ethnic medicine Cynanchum komarovii Al. Iljinski

Ethnopharmacological relevanceCynanchum komarovii Al. Iljinski is a ethnomedicinal herb and this ethno-medicine is used mainly to treat arthritis, toothache, reducing phlegm, relieving cough. Total alkaloids of Cynanchum komarovii Al. Iljinski (TACKI) is the main active compound of Cynanchum komarovii Al. Iljinski. Previous investigations have revealed that TACKI can significantly inhibit rat foot swelling caused by carrageenan; it has a significant inhibitory effect on granulation tissue proliferation. Pharmacology study showed that Cynanchum komarovii Al. Iljinski has analgesia, anti-inflammatory, antibacterial, anti-tumor, relieving cough and relieving asthma. However, there is no any investigation on the mechanism of analgesia and anti-inflammation. Aim of the studyTo clarify the analgesic effect and material basis of Cynanchum komarovii Al. Iljinski, determine the analgesic effect of TACKI, and provide experimental data support for its traditional application in the treatment of various pains. Materials and methodsTACKI were prepared by the traditional acid extraction and alkaline precipitation method, and TACKI was analyzed through classic animal models of acute antinociceptive animal models and chronic antinociceptive. Evaluation of analgesic effects, and preliminary discussion of the mechanism of its analgesic effects were performed in this work. ResultsAcute toxicity experiments showed that the LD50 of TACKI mice was 2960.88 mg/kg, and symptoms of poisoning appeared. Patholog of liver and kidney studies have shown that TACKI reduces eosinophils and increases basophils in kidney glomeruli. In the study of analgesic effects, TACKI had analgesic activity through the PWL, formalin test, and acetic acid writhing test. In the chronic inflammatory antinociceptive study, the latency of the withdrawal reflex in the TACKI group was prolonged, and the mechanical withdrawal reflex threshold was significantly increased. The protein expression of NMDA, GFAP and Iba-1 in rat brain tissue can be reduced significantly byTACKI. Meanwhile, the content of TNF-α and IL-6 in rat brain tissue is reduced. ConclusionTACKI has a significant analgesic activities. It may be related to inhibiting the activation of astrocytes and reducing the content of inflammatory mediators.

Physicochemical Characteristics of Activated Carbon Impregnated with Different Type of Metal Oxide Nanoparticles towards Hydrogen Sulfide Removal

It is highly anticipated to understand the influence of physicochemical characteristics of different types metal oxide nanoparticles impregnated onto palm shell activated carbon (PSAC) adsorbent towards hydrogen sulfide (H 2S) removal. Alkaline precipitation method was used to synthesis metal oxide nanoparticles (CeO 2, NiO, CuO, and Fe 2O 3). The synthesised metal oxide nanoparticles were then impregnated in the pre-oxidized PSAC adsorbents (Ce/PSAC, Ni/PSAC, Cu/PSAC and Fe/PSAC). The prepared adsorbent was then analysed via Scanning Electron Microscope – Energy Dispersive X-ray (SEM-EDX), Thermogravimetric analysis (TGA), Fourier-transform infrared spectroscopy (FTIR) and H 2S adsorption analysis. Based on H 2S adsorption study, different types of metal oxide nanoparticles impregnated on PSAC adsorbent showed different trend of breakthrough time and adsorption capacity. PSAC adsorbent that was modified with metals oxide nanoparticles shows efficient result compared to raw PSAC adsorbent. Among metal oxide nanoparticles, Cu/PSAC adsorbent gives the higher adsorption capacity (86.60 mg H 2S/g Cu/PSAC) and breakthrough time (80 minutes) compared to the rest of adsorbents.

Influence of Surface Characteristics of Palm Shell Activated Carbon Modified with Nanostructured Nickel for Reactive Adsorption of Hydrogen Sulfide

ABSTRACT Hydrogen sulfide (H2S) is a colourless and toxic gas that could harms people and environment. Due to its acidic and toxic properties, H2S cannot be burnt directly, hence it is necessary to remove it. The aim of this work is to study the influence of surface characteristics of modified palm shell activated carbon (PSAC) with Nickel nanoparticles (Ni nps) towards H2S removal. Surface characteristics consist of a combination of various analysis on the adsorbent’s surface such as, surface morphology, surface area, surface porosity, and surface functional groups. The Ni nps were synthesized by using alkaline precipitation method at different synthesis parameters; pH (8 – 10), precipitant molarity (6.5M – 7.5M) and temperature (55◦C – 65◦C). To study the adsorption of H2S, the PSAC adsorbent was modified with the synthesized Ni nps at 400◦C for 3 hours. The performance of modified Ni nps with PSAC (Ni-PSAC) adsorbents were tested in a custom-design H2S scrubber for H2S removal application. The surface characteristics of modified Ni-PSAC adsorbent were analysed by using TGA, TEM, SEM, and FTIR. Among the impregnated adsorbents, Ni-PSAC with pH 10, 6.5 M of precipitant molarity and temperature of 65◦C gives the highest adsorption capacity (9.60 mg H2S/g Ni-PSAC) and breakthrough time (14 minutes) compared to the rest of adsorbents. The introduction of Ni nps in the PSAC adsorbent structures resulted in better H2S removal compared to unimpregnated PSAC adsorbent. The existence of Ni nps help to increase the availability of oxygen vacancies in the adsorbent with the aid of nanostructured added in the adsorbent.

Folic Acid-Functionalized, Condensed Magnetic Nanoparticles for Targeted Delivery of Doxorubicin to Tumor Cancer Cells Overexpressing the Folate Receptor.

This study concerns the development of folic acid (FA)-functionalized iron oxide condensed colloidal magnetic clusters for a more selective delivery of doxorubicin (DOX) to tumor cancer cells overexpressing the folate receptor. Alginate-coated condensed magnetic nanoparticles (co-MIONs) were synthesized via an alkaline precipitation method of an iron precursor in the presence of sodium alginate. Poly(ethylene glycol) (OH-PEG-NH2) was conjugated to the carboxylic acid end group of alginate and folic acid (FA) was conjugated to the hydroxyl terminal group of PEG to produce folate-functionalized, pegylated co-MIONS (Mag-Alg-PEG-FA). The physicochemical properties of nanoparticles were fully characterized. DOX was loaded on the nanoparticles, and the cellular uptake and anticancer efficacy of the nanoparticles were examined in cancer cell lines expressing and not expressing the folate receptor. The biocompatibility of the carrier (blank nanoparticles) was also evaluated by cytocompatibility and hemocompatibility experiments. The nanoparticles exhibited sustained DOX release in aqueous buffers and biorelevant media, which was responsive to pH and external alternating current magnetic fields. The effect of the magnetic field on DOX percentage release appeared to be independent of the timing (onset time) of magnetic field application, providing flexibility to the magnetic control of drug release from the nanoparticles. The blank nanoparticles were not cytotoxic and did not cause hemolysis. The DOX-loaded and FA-functionalized nanoparticles exhibited increased uptake and caused increased apoptosis and cytotoxicity against the MDA-MB-231 cell line, expressing the folate receptor, compared to the MCF-7 cell line, not expressing the folate receptor. The application of a 0.5 T magnetic field during incubation of the nanoparticles with the cancer cells increased the cellular uptake and cytotoxicity of the nanoparticles. The obtained results indicate the potential of the folate-functionalized, pegylated co-MIONS for a more efficacious DOX delivery to cancer cells of solid tumors.

Non-thermal plasma oxidation of Cu(II)-EDTA and simultaneous Cu(II) elimination by chemical precipitation

Cu2+ readily complexes with ethylenediaminetetraacetic acid (EDTA) to form a heavy metal complex (Cu-EDTA) that is typical in the effluents from mining and electroplating industries. It was difficult for the classical alkaline precipitation method to eliminate the heavy metal complex due to the strong bonding ability between Cu(II) and EDTA. Cu(II) release and removal performance after Cu-EDTA decomplexation in a non-thermal plasma oxidation system was carried out in this study. The removal process was characterized by chemical oxygen demand, total organic carbon, atomic force microscopy, and electroconductivity analysis. The toxicity effect of the treated Cu-EDTA solution was also tested by photobacterium bioassay. The experimental results showed that 80.2% of Cu was released and removed within 60 min of the non-thermal plasma treatment/alkaline precipitation. Relatively higher energy input, lower Cu-EDTA concentration, and acidic conditions were necessary to obtain greater Cu release and removal performance, and there existed an appropriate air flow rate for high-efficient Cu release and removal. O2−, OH, 1O2, and O3 were the main active substances leading to Cu2+ release. Its residual toxicity to P.phosphoreum sp.-T3 was significantly reduced after treatment.

Biosynthesis of magnesium oxide (MgO) nanoflakes by using leaf extract of Bauhinia purpurea and evaluation of its antibacterial property against Staphylococcus aureus

Nanobiotechnology has become a newly evolving field of interest in biomedical applications due to its biocompatibility and non-toxic nature towards the environment. Metal and metal oxide nanoparticles have been widely used as an antibacterial agent due to the emergence of antibiotic resistant pathogens, which leads to the outbreak of infectious diseases. In the present paper, biogenic synthesis of magnesium oxide (MgO) nanoflakes is reported by using Bauhinia purpurea leaf extract through alkaline precipitation method along with its detailed characterization. The average size of synthesized nanoflakes was found to be around 11 nm. Electron microscopy was used to investigate the morphology of the MgO nanoflakes. Additionally, the presence of antioxidants, phenolics and flavonoids in B. purpurea leaf extract has been studied by using different assays, which suggested the efficacy of leaf extract as a potential reducing agent for MgO nanoflakes synthesis. Antibacterial activity of synthesized MgO nanoflakes was investigated against Staphylococcus aureus, a gram positive bacteria known to cause various infections in humans. Results suggested the high efficacy of MgO nanoflakes as a potential antibacterial agent against S. aureus at meager dose size (250 μg/ml) and possible mode of action was investigated through surface morphology analysis of bacterial cells by field emission scanning electron microscopy.

Iron oxide nanoparticles as dielectric and piezoelectric enhancers for silicone elastomers

Iron oxide nanoparticles were prepared using an alkaline precipitation method to tune the reaction time so as to afford ferrihydrite with spherical morphology or goethite nanorods. These two nanoparticle types, surface-treated with a surfactant (Pluronic L81), were each incorporated in 10, 20 and 30 wt% within a polydimethylsiloxane-α,ω-diol (Mn = 60 000 g mol−1). The mixtures were processed as films and crosslinked by condensation with tetraethoxysilane at room temperature. The aged films were investigated concerning filler distribution (by SEM coupled with an energy-dispersive x-ray spectroscopy module), mechanical (tensile strength, elongation and Young’s modulus), and dielectric properties (permittivity, loss, conductivity and strength). The results show that the fillers have a relatively homogeneous distribution within the matrix and, dependent on the filler nature and amount, generally manifest a mechanical reinforcing effect and act as dielectric permittivity and strength enhancers. In addition, it has been found that the crystalline nanoparticles induce a piezoelectric response, emphasized by piezoelectric force microscopy. The improved properties of the composites make them suitable for applications in mechanical/electrical energy conversion, as theoretical estimates showed.

Photocatalytic Degradation of Toxic Methyl Red Dye Using Silica Nanoparticles Synthesized from Rice Husk Ash

Herein we reported the preparation and potential application of SiO2 NPs (SiO2 NPs) for the photocatalytic degradation of methyl red dye in aqueous medium. These are synthesized from rice husk ash (RHA) which was collected from rice mill near Shankaraghatta (Shimoga, Karnataka). Silica was present in large quantity in RHA, hence it can be extracted by an alkaline precipitation method was developed to produce pure silica xerogel. From XRD and FTIR analysis revealed the amorphous nature of SiO2 NPs along with the presence of siloxane group. TEM image confirms the formation of SiO2 NPs at 10 to 20 nm range. Furthermore the stabilization and formation of SiO2 NPs was confirmed by SEM/EDAX and TEM analysis. The photo catalytic activity of prepared pure SiO2 NPs towards remediation of dyes like Methyl red (MR) dye has been tested.

Magnetite: Synthesis and Characterization

Magnetite nanopowder is a nanostructured magnetic material which is of great importance due to its electric and magnetic properties at room temperature. There are quite enough methods to produce magnetite. In the present work, four samples of magnetite powder were produced, the first three with the alkaline precipitation method from aqueous solution of mixed Fe (II)/Fe (III) salts, without any surfactants and the last one with the micro emulsion method. The prepared powders have been characterized using transmission electron microscopy, Raman and FT-IR spectroscopy and x-ray diffraction in order the structure and the morphology of magnetite to be examined. The produced magnetite powders have a size range of 10-12±2nm and the chemical composition of magnetite.

A study of phosphate adsorption by different temperature treated hydrous cerium oxides

An alkaline precipitation method was introduced to produce hydrous cerium oxides. The prepared powder was characterized by Brunauer-Emmett-Teller (BET) nitrogen adsorption-desorption, X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectrometry, and thermal gravimetry (TG) approaches. The adsorbent has a chemical formula of CeO2·nH2O (n < 2) and a cubic fluorite-type structure after high temperature treatment. Adsorption capacity of different temperature treated hydrous cerium oxides does not directly correlate with BET specific surface area. Phosphate adsorption isotherms follow the Langmuir equation below the treatment temperature of 800°C. Phosphate adsorption causes no change on the structure of a hydrous cerium oxides, and no signs of CePO4 precipitates are found. The ion-exchanging structure of hydrous cerium oxide plays a fundamental role in phosphate adsorption. The structure is highly temperature resistant and forms adsorption sites which adsorb both water and some anions. Complete loss of adsorption ability cannot be achieved unless the treatment temperature is higher than 1200°C. Mechanism study shows that the adsorption of phosphates is mainly an anion-exchange process.

Size-controlled layered zinc hydroxide intercalated with dodecyl sulfate: effect of alcohol type on dodecyl sulfate template

Layered zinc hydroxide intercalated with dodecyl sulfate (LZH-DS) was prepared by facile alkaline precipitation method in a short reaction time at room temperature. We also controlled the size of the layered structures with different kinds of alcohols (ethanol, 1-propanol, 1-butanol and 1-pentanol), and not by controlling variables such as process temperature and aging time. The synthetic mechanism of large LZH-DS was explained using concepts of the extra- and intra-lamellar template models. The extra-lamellar template consisted of a few SDS bilayers in which zinc atoms electrostatically interacted with sulfate groups and the alcohols were laterally located between dodecyl sulfate molecules. Due to hydrophobic and ion-dipole interactions, the extra-lamellar template with the long alkyl chain alcohols was more packed and had greater stability resulting in formation of large LZH-DS. Regardless of the type of alcohol, the LZH-DS was octagonal shaped. The SAED pattern displayed hexagonally arranged spots, which was considerably different from the overall octagonal shape of LZH-DS. On the basis of TGA and EDS results, the chemical formula of LZH-DS synthesized with 1-pentanol was Zn(OH)1.42(C12H25SO4)0.47(Cl)0.11·0.90H2O, and the crystal structure was a hydrozincite-type structure.

Ferrofluids of magnetic multicore nanoparticles for biomedical applications

For a variety of magnetically based biomedical applications, it is advantageous to use sedimentation stable suspensions of relatively large ( d>20 nm) magnetic core–shell nanoparticles. Water-based suspensions of multicore nanoparticles were prepared by coating of the particles (synthesized by means of a modified alkaline precipitation method) with a carboxymethyldextran shell. The resulting ferrofluids were structurally and magnetically characterized. It was found that these fluids show a specific heating power of about 60 W/g ( f=400 kHz, H=10 kA/m). This value was increased up to 330 W/g by a simple fractionation method based on centrifugation. Finally, the cellular uptake of the multicore nanoparticles was demonstrated.

Synthesis of hydroxyapatite by means of the alkaline precipitation method

Hydroxyapatite, having a crystallinity similar to biological apatites, is required for X-ray crystallographic and other studies in biological apatites.Our studies were made on synthesized compounds having a crystallinity similar to human enamel prowder. Hydroxyapatite was prepared by a modification of the alkaline precipitation method of Napper.The synthetic hydroxyapatite X-ray powder diffraction patterns were similar to human dental enamel and suggested a similar degree of crystallinity.Analysis of the composite hydroxyapatite sample showed that the Ca: P ratio was 1.62±0.02. The sample was thus calcium-deficient hydroxyapatite, but here too, it was similar to human dental enamel.