Hydroxide Compounds Research Articles

The Effect Of The Addition Of Activated Charcoal To Different Formulations Of Calcium Hydroxide On Their Effect On The Fracture Resistance Of Endodontically Treated Teeth.

This study aimed to evaluate the effect of the addition of the activated charcoal to different formulations of calcium hydroxide on the fracture resistance of endodontically treated teeth. Ninety one freshly human extracted single rooted teeth were selected. The samples were cleaned and shaped and classified according to the type of the dressing into five groups; Group 1; (21 samples) dressed with calcium hydroxide paste with Iodoform ( Metapex) (META,Chungcheongbuk-do,Korea ), Group 2; (21 samples) dressed with conventional calcium hydroxide with saline(GAMA dental lab,Cairo, Egypt ). Group 3; (21 samples) dressed with calcium hydroxide paste with Iodoform mixed with activated charcoal ( Eucarbon Sedico, Cairo, Egypt) and Group 4; (21 samples) dressed with conventional calcium hydroxide and activated charcoal with saline and Group 5; Control group (undressed). The samples were further classified according to the observation time into: Subgroup A; (7 samples) after two weeks. Subgroup B;(7 samples) after one month and Subgroup C; (7 samples) after two month. Samples were loaded vertically after the observation periods using Universal Testing Machine until fracture. The results showed that the fracture resistance of the samples dressed with either Metapex or conventional calcium hydroxide showed lower resistance to fracture than those dressed with either two formulations with activated charcoal. It was concluded that the addition of activated charcoal to the calcium hydroxide compounds can decrease their weakening effect on the endodontically treated teeth.

Selectively Determination Trace Amounts of Polycyclic Aromatic Hydrocarbons from Water and Wastewater Matrices Using Graphitic Carbon Nitride/Layered Double Hydroxide Nanocomposite on Porous Anodized Aluminum Wire as SPME Fiber

Synthesis a well-suited coating for solid phase microextraction (SPME) fiber is essential point due to determination trace amounts of analytes from water and wastewater samples. So, the new coating was built onto the porous anodized aluminum wire incorporated with layered double hydroxide compound and modified solvothermally with graphitic carbon nitride and used as fiber coating for selectively analysis of polycyclic aromatic hydrocarbons by HS-SPME method. According to the results, this coating indicated considerable potential due to extract simultaneously trace amounts of some carcinogenic polycyclic aromatic compounds in different matrices. Essential parameters such as microextraction time, microextraction temperature, agitation speed and ionic strength of the sample solution that mainly affect the adsorption process were optimized and in the optimum values, repeatability data of one fiber that changed between 4.7% and 7.7% for the test compounds were achieved. Detection limits for the studied compounds were between 0.002 to 0.32 µg L−1. It is a simple, quick, and cheap approach. There is stability in the fiber in terms of temperature, and great recoveries are obtained by its use.

Binary transparent (Ho1-xDyx)2O3 ceramics: Compositional influences on particle properties, sintering kinetics and Faraday magneto-optical effects

Binary transparent magneto-optical (Ho1-xDyx)2O3 (x = 0.01–1) ceramics derived from layered rare-earth hydroxide (LRH) compounds were fabricated by vacuum sintering. They have in-line transmittances of ∼67‒77 % at the visible wavelength of 700 nm and ∼77‒84 % at the mid-infrared wavelength of 5 μm with similar maximal infrared cut-off at ∼9.5 μm. The impacts of Dy3+ doping on particle properties, sintering kinetics and Faraday magneto-optical effects were systematically investigated. The results show that (1) The LRH precursors exhibit the nanosheet morphology with the thickness of ∼6‒10 nm. Dy3+ incorporation not only induces an expansion for the hydroxide host layer but also a contracted interlayer distance; (2) Upon calcination at 1100 °C, the LRH nanosheets collapse into sphere-like oxide particles. The addition of Dy3+ leads to increasing lattice constants and decreasing theoretical densities for the (Ho,Dy)2O3 solid solutions; (3) A smaller bandgap energy for Dy2O3 (∼4.85 eV) was obtained relative to those of (Ho0.9Dy0.1)2O3 (∼5.24 eV) and Ho2O3 (∼5.31 eV); (4) Dy3+ dopant promotes grain growth and the pure Dy2O3 bulk has a rather smaller grain-boundary-diffusion controlled activation energy (∼457 kJ/mol) than the (Ho0.9Dy0.1)2O3 counterpart (∼626 kJ/mol); (5) The Verdet constants of magneto-optical (Ho1-xDyx)2O3 ceramics generally linearly increase with the rise of Dy3+ concentration.

Sustainable Ecocements: Chemical and Morphological Analysis of Granite Sawdust Waste as Pozzolan Material.

The processes focused on stone cutting generate a large volume of waste. Small size waste, silt/clay, is not used and goes to landfill. However, the composition of these wastes makes them useful for adding to cements and for use in construction. In the present paper, 10% Ordinary Portland cement is replaced by 10% waste from granite sawmill, which is studied to obtain sustainable ecological cement. This replacement provides advantages from the morphological and chemical point of view at the cements. The waste has a particle size that does not exceed 15 µm and that when replacing in the cement, after the hydration reaction, generates structures where Calcium Silicate Hydrate (C-S-H) gels and double layered hydroxide compounds (LDH) are reaction products formed in high concentration. These products develop stable phases in the structures over long time periods such one year, which was the time frame used in this study.

Improving Fire Performances of PEAL: More Second-Life Options for Recycled Tetra Pak®.

The purpose of this work was to evaluate and improve the flammability and combustion behavior of the polyethylene-based material obtained from the recycling of Tetra Pak® (PEAL) to widen its use to applications where these properties are required. Firstly, its thermal stability was investigated with thermogravimetric analysis, resulting in an enhancement in the main degradation step temperature (from 385 °C to 421 °C) due to the presence of the aluminum-flakes. Then, to improve the poor flammability (HB in UL-94 test) and combustion behavior (Fire Performance Index of 0.07) of the raw material, two flame retardant approaches were tested: an intumescent system made of ammonium polyphosphate and pentaerythritol, and magnesium hydroxide. In addition, the effectiveness of polyethylene as a charring agent was evaluated. Characterization was made with UL-94, cone calorimeter, and morphologic analysis. For all the materials tested, the temperature of the main weight loss step increased and the flammability rating improved (V2 for intumescent and V0 for magnesium hydroxide reached). Moreover, fire hazard decreased (Fire Performance Index of 0.15 and 0.55; Flame Retardancy Index of 2.6 and 10.0). Referring to the morphology, full compatibility was found in the PEAL–magnesium hydroxide compound, while PEAL-intumescent appeared as a heterogeneous system.

ANALISIS MISKONSEPSI PESERTA DIDIK KELAS XII MENGGUNAKAN TES DIAGNOSTIK THREE-TIER MULTIPLE CHOICE PADA MATERI HIDROKARBON

This study aims to identify misconceptions experienced by students in class XII in MAN A and SMAN B in Cirebon City on hydrocarbon material. The research method used is quantitative descriptive method. The sampling technique or subjects used cluster random sampling technique, where the subjects in this study were students of Class XII MIPA 2 in MAN A of the Cirebon City and XII Science 1 in SMAN B of the Cirebon City with the number of students from two schools as many as 45 people. The instrument used is the Three-Tier Multiple Choice Diagnostic Test by categorizing the understanding of concepts possessed by students. The category is divided into three, namely, understanding the concept, not understanding the concept and misconception. The results showed that students in MAN A of the Cirebon City and SMAN B of Cirebon City experienced the highest misconception in the sub-material types of carbon atoms and hydroxide compounds. While the lowest misconception is in the sub-material grouping of hydrocarbon compounds in both schools. The causes of misconceptions of students due to associative thinking, humanistic thinking, incomplete reasoning, students' interest and motivation to learn, abstract chemical concepts, teachers do not optimize learning strategies. Keywords: Misconceptions, Three-Tier Diagnostic Tests, Hydrocarbons

MAIN CHARACTERISTICS OF SYNTHESIZING PROCESSES OF MAGNETITE AND IRON NANOPOWDERS BY HYDROGEN REDUCTION FROM HYDROXIDE COMPOUND

Purpose. Study of the main characteristics of synthesizing processes of magnetite and iron nanopowders by hydrogen reduction from hydroxide compound (α-FeOOH). Materials and methods. α-FeOOH hydroxide nanopowder was obtained by chemical precipitation from aqueous solutions of iron (III) nitrate Fe(NO3)3 (10 wt. %) and alkali NaOH (10 wt. %) at room temperature, pH = 11, under the condition of continuous stirring. Synthesizing processes of Fe3O4 and Fe nanopowders by hydrogen reduction of hydroxide α-FeOOH were carried out in a tubular furnace SNOL 0.2/1250. The study of the crystal structure as well as the composition of the powder samples was performed by X-ray phase analysis. The size and morphology of nanopowder particles were investigated by scanning and transmission electron microscopes. The specific surface area of the powders was measured by using BET method by low-temperature nitrogen adsorption. The average size of the powders articles was determined via the measured value of specific surface area. Results. It has been established that the optimal temperatures corresponding to the values of the maximum specific rate for carrying out the synthesizing processes of Fe3O4 and Fe nanopowders by hydrogen reduction are 340 and 500 °C, respectively. The resulting products are nanopowders of pure Fe3O4 and Fe after being through hydrogen reduction process for 2 hours. It was shown that Fe3O4 nanoparticles consist of particles with indefinite shape, which are prone to the formation of flakes. They have a nanometer size (about tens of nm) and are in a sintered state with connections to several neighboring particles by isthmuses. Fe nanoparticles are mainly rounded and spherical, up to one hundred nm in size and distributed separately. Originality. For the first time, the optimal temperatures have been established for synthesizing processes of Fe3O4 and Fe nanopowders by hydrogen reduction from hydroxide compound. Practical value. The research results will serve as a basis for the synthesis of nanopowders based on Fe3O4 and Fe, guarantee the acceleration of processes, ensure the necessary properties of nanopowders and can be used for various fields of science, technology, ecology and oth.

CuMgAl hydrotalcite as an efficient bifunctional catalyst for the cross-dehydrogenative C–C coupling reactions under mild conditions

CuMgAl layered double hydroxide compounds (CuMgAl-LDHs) have been synthesized, characterized and investigated in the aerobic CDC reactions. The results indicated that NH3·H2O coprecipitated CuMgAl LDH (N-CuMgAl-LDH) was able to efficiently accelerate the CDC reactions between the α-Csp3–H of N-aryltetrahydroisoquinolines and nucleophiles. A wide scope of N-aryltetrahydroisoquinoline analogues and nucleophiles with different CH bonds (Csp3–H, Csp2–H and Csp–H) could be tolerated by the N-CuMgAl-LDH system. Compared with the sample using Na2CO3 as the precipitant (C-CuMgAl-LDH), N-CuMgAl-LDH showed higher catalytic activity, which probably was due to its higher surface acidity. Dual function of redox and acidity for the N-CuMgAl-LDH catalyst has been observed in the CDC reaction. According to the obtained catalytic results, kinetic isotope effect experiment and XPS analysis, iminium ion was proposed as the key intermediate, made possible by the cycle of Cu2+ and Cu+ under the aerobic conditions.

Real-time visualization of Zn metal plating/stripping in aqueous batteries with high areal capacities

Zinc aqueous batteries have attracted great attention due to the earth abundance and the low redox potential of Zn metal. Utilizing Zn metal as an anode, however, causes low coulombic efficiency stemming from a dendritic Zn plating and formation of byproducts such as hydrogen gas, solid zinc hydroxide and salt-related compounds. One effective way of mitigating the issues is to modify the solvation structure of the electrolyte to increase the energy barrier of the water molecules for hydrolysis and electrolysis. Nevertheless, Zn aqueous batteries still indiscriminately utilize several types of electrolytes without elucidating the correlation between electrolyte composition and the electrochemistry of Zn metal. Here, we use operando optical microscopy to visualize the microstructural evolution of Zn metal, which strongly affects the electrochemical reversibility. In ZnSO4 electrolyte, large Zn platelets grow and form loose agglomerates vulnerable to unexpected delamination from the electrodes. In Zn(OTf)2 electrolyte, Zn platelets nucleate more homogeneously and grow smaller, which forms denser agglomerates enabling more stable cycling. We further reveal that the formation of a stable solid-electrolyte interphase layer holds the key to the excellent performance of acetonitrile-hybrid water-in-salt electrolytes. Our results show the necessity of designing proper electrolytes to develop long-life Zn aqueous batteries.

The effect of exposure conditions on performance evaluation of post-treated anodic oxides on an aerospace aluminium alloy: Comparison between salt spray and immersion testing

In this work, the effect of the corrosion testing methodology on the degradation of anodized and post-treated AA-2024T3 specimens is considered. Two post-treatments are selected for the anodized layers, namely hydrothermal sealing and cerium-based post treatment. The two post-treatments are selected such that in one case corrosion protection mainly arises from a barrier effect (hydrothermal sealing) and in the other it arises from active inhibition (cerium-based treatment). It is found that salt spray and immersion testing provide similar results for the hydrothermally sealed oxides, but differ substantially for the cerium-treated oxides. The discrepancy is due to the fact that the continuously refreshing electrolyte layer during salt-spray testing promotes film dissolution and hinders precipitation of aluminium hydroxide and cerium compounds, unlike in stagnant bulk electrolyte. Hence, salt-spray testing is likely to be more aggressive than immersion testing for those systems that rely on active inhibition.

Adsorption and Diffusion Moderated by Polycationic Polymers during Electrodeposition of Zinc.

Electrodeposition of metals is relevant to much of materials research including catalysis, batteries, antifouling, and anticorrosion coatings. The sacrificial characteristics of zinc used as a protection for ferrous substrates is a central corrosion protection strategy used in automotive, aviation, and DIY industries. Zinc layers are often used for protection by application to a base metal in a hot dip galvanizing step; however, there is a significant interest in less energy and material intense electroplating strategies for zinc. At present, large-scale electroplating is mostly done from acidic zinc solutions, which contain potentially toxic and harmful additives. Alkaline electroplating of zinc offers a route to using environment-friendly green additives. Within the scope of this study an electrolyte containing soluble zinc hydroxide compound and a polyquarternium polymer as additive were studied during zinc deposition on gold model surfaces. Cyclic voltammetry experiments and in-situ electrochemical quartz crystal microbalance with dissipation (QCM-D) measurements were combined to provide a detailed understanding of fundamental steps that occur during polymer-mediated alkaline zinc electroplating. Data indicate that a zincate-loaded polymer can adsorb within the inner sphere of the electric double layer, which lowers the electrostatic penalty of the zincate approach to a negatively charged surface. X-ray photoelectron spectroscopy also supports the assertion that the zincate-loaded polymer is brought tightly to the surface. We also find an initial polymer depletion followed by an active deposition moderation via control of the zincate diffusion through the adsorbed polymer.

The effect of surfactants on the particle size of iron, cobalt and nickel nanopowders

This paper studies the effect of surfactants on the particle size of metal nanopowders (NPs): iron, cobalt and nickel synthesized using chemical-metallurgy method – hydrogen reduction of hydroxide compounds FeOOH, Co(OH) 2 and Ni(OH) 2 at 400, 285, and 280 °С, respectively. These hydroxides were pre-synthesized via chemical deposition from the corresponding nitrate solutions with NaOH alkali solution (10 wt.%) using sodium dodecyl sulfate (SDS) (0.1 %) and ethylenediaminetetraacetic acid disodium salt (EDTA) (0.3 %). The obtained NPs were studied using such methods as X-ray diffractometry (XRD), scanning electron microscopy (SEM), and measurements of the specific surface area by low-temperature nitrogen adsorption. According to XRD shows that all the obtained samples of NPs Fe, Co and Ni contain pure metallic phases. The results of electron microscopic analysis and measurement of the specific surface area of powder samples show that the addition of various surfactants to the initial synthesis medium of hydroxide compounds has a significant effect on the size and morphology of the obtained NPs. It was found that the addition of 0.1 % SDS leads to a decrease in the average size of the obtained particles, and the presence of 0.3 % EDTA contributes to the formation of larger metal particles. It was shown that the use of 0.3 % EDTA in deposition of initial hydroxide precursors makes it possible to obtain metal NPs with the narrowest crystallite size distributions.

Electrodeposition of Ni[sbnd]Co alloy from methansulfonate electrolyte. The role of the electrolyte pH in the anomalous codeposition of nickel and cobalt

The kinetic characteristics of the electrochemical codeposition of nickel and cobalt from a methanesulfonate electrolyte have been investigated. An analysis of the partial voltammograms of the nickel and cobalt deposition into the alloy showed that the potentials of the metal deposition into the alloy are significantly shifted in a positive direction compared to the deposition of the pure metals. This effect is more pronounced in the case of cobalt, and is the cause of the anomalous codeposition of nickel and cobalt. In the presence of the H3BO3 as a buffering agent in the electrolyte, the electroreduction of nickel(II) and cobalt(II) ions is inhibited; this reveals a significant role of the near-electrode pH in the kinetics of these reactions. The thermodynamic and kinetic aspects of the NiCo alloy electrodeposition were considered. It has been found that the kinetic factor is the determining factor responsible for the anomalous codeposition of nickel and cobalt. It has been shown that an adequate explanation of the observed regularities is possible using a concept that assumes equally accessible electroreduction of alloy components at the catalytic centers formed during the adsorption of their hydroxo complexes on the electrode surface. Based on the proposed mechanism, a kinetic model has been developed that correctly describes the features of nickel and cobalt codeposition.It has been found that the microhardness and internal stresses of NiCo electrolytic alloys obtained from methanesulfonate electrolytes are higher than those of coatings deposited from sulfate electrolytes. This is due to the difference in the degree of distortion of their crystal lattices. The low buffering properties of methanesulfonate electrolytes in comparison with sulfate electrolytes cause the formation of a greater number of hydroxide compounds in the near-electrode layer, which are incorporated into the cathode deposit and affect its structure.

Surface defect formation in polyimide film via ion migration from glass substrate

Migration of ions such as sodium from a glass surface to organic materials in contact is critical for the use of glass as a supporting material for film casting. In this study, we report the surface defect formation of annealed poly(pyromellitic dianhydride-co-4,4′-oxydianiline) (PMDA-ODA) film after detaching the film from soda-lime glass via ion migration. The defect was porous and sodium was observed as one of the major impurities in the defect. We propose that the defect forms as a result of the ion migration from glass and thermal decomposition of PMDA-ODA. The ions released from glass at a sufficiently high temperature form hydroxide compounds during the floating of the film on the water and readily attacks the imide ring at the glass-film interface. The ionic bonds are broken by thermal annealing and diffuse throughout the film, finally defects form by both segregation of ions to the film surface and PMDA-ODA decomposition.

The effect of nano-additives on the processes of electrodeposition of nickel precipitation

The article presents the results of investigates of the effect of ultrafine additives (zirconium diboride, silicon carbide, diamond) on the physical and mechanical properties of composite electrochemical nickel deposits obtained from colloid-electrolyte baths. It was revealed that the most effective nanostructured additives are zirconium diboride and ultrafine diamond. Current efficiency and potentiostatic researches shew mutual participation of finely dispersed nickel hydroxide compounds in the formation of a composite electrochemical deposits and dispersed phase of zirconium diboride or ultrafine diamond that are attendant in the solution or formed during electrolysis and introduced into the electrolyte. It is shown that the optimal values of internal tensions and microhardness are associated with the hardening of the nickel matrix together with various nano-dispersed additives that are included in the deposit. These deposits can be used as an alternative to chrome deposits on parts of machinery.

SYNTHESIS OF COMPLEX OXIDE COMPOSITIONS OF COBALT–MANGANESE AND CERIUM–ZIRCONIUM AND THEIR CATALYTIC ACTIVITY IN THE DECOMPOSITION OF HYDROGEN PEROXIDE

Cobalt oxides and/or manganese and their com-position based on cerium and zirconium oxides (CeO2 : ZrO2 = 1:1 mol.%) with a content of up to 20 wt. % are synthesized. Samples of both individual oxides and complex oxide compositions were prepared by precipitation from solutions of am-monia (room temperature) or hexamethylenetet-ramine (80–90 °C) followed by heat treatment. Results of DTA show, that due to the calcination at 400 ° C (2 h), the obtained samples lose 17–22 wt. % corresponding to 2–3.8 molecules of water. According to the X-ray powder analysis, initially are formed hydroxide compounds of cobalt (CoO· xH2O) and manganese (MnO2·yН2О), which, after being heated at 400 °C for 2 hours, are converted into mixed oxides from the composition of Co3O4 and Mn3O4. The average particle size calculated by the Sherer equation is 18–30 nm.
 In the study of catalytic activity on the example of the reaction of the hydrogen peroxide decomposition, it was found that the obtained samples from the solution of GMTA show a greater ability to catalytically decompose hydrogen peroxide compared to samples obtained from the ammonia solution. In this case, the catalytic activity of dried samples is twice as high as roasted, regardless of the method of obtaining. Samples of oxide compo-sitions with deposited 5–10 wt. % of Ce–Zr oxides (1:1) exhibit the highest ability to decompose H2O2. In this case, samples of compositions obtained from the solution of GMTA, have a prolonged catalytic action, and when precipitation in the solution of ammonia, the reaction takes place quite actively during 4–5 days.
 Compositions formed from co-deposited or mechanically mixed hydroxocompounds of cobalt and manganese with 5 wt. % of CeO2–ZrO2 (1:1) deposited on them have different catalytic activity. In the case of mechanically mixed, it is 30% lower and with subsequent calcination at 400 °C, it is reduced by almost half, and with co-precipitation, the activity is quite high and does not change with heat treatment. In the case of obtaining samples of Co–Mn with Ce–Zr (1:1) deposited on them in excess of 10 wt. % the catalytic activity of the samples dried at 80 °C is equal to the activity of the co-deposited hydroxocompounds of cobalt and manganese and the calcination at 400 °C it reduces it by 30 %.
 The best ability for catalysis was found in samples CoO·xH2O + 5 wt. % MnO2·yН2О, СоO×хН2О + 10 wt. % CeO2:ZrO2 and СоO×хН2О–MnO2×yН2О, precipitated with the GMTA solution and dried at 80 °C. The besser catalytic properties revealed a sample of СоО×хН2О + 10 wt. % CeO2:ZrO2, which with-out stirring is capable of decomposing 1.2–1.4 dm3/g of hydrogen peroxide with a rapid reaction and in the experiment the volume of H2O2 reacted was 3.4 dm3/g.

Rational assembly of mussel-inspired polydopamine (PDA)-Zn (II) complex nanospheres on graphene oxide framework tailored for robust self-healing anti-corrosion coatings application

Abstract There are increasing demands for self-healing anti-corrosion coatings with high efficiency and durability in various industrial applications. Recently, eumelanin polymers especially polydopamine (PDA)-based nanostructures have been served as a mussel-inspired strategy to provide such requirements due to the intrinsic adhesive nature of amines and catechols along with its film-forming ability. Nevertheless, direct embedment of hydrophilic PDA nanoparticles into polymer coatings could eventually trigger corrosion as a consequence of the osmotic pressure exerted beneath the coating. In the present work, we have adopted a rational design for constructing robust self-healing epoxy composites via a tailor-made procedure including oxidative polymerization of dopamine over the graphene oxide (GO) framework and subsequent loading of Zn (II) corrosion inhibitor. The triple-function of GO as a template for polymerization of dopamine; simultaneously being a nanoreservoir for storage of corrosion inhibitors and eventually as an impermeable barrier is very crucial. Curiously, the as-prepared GO-PDA and GO-PDA-Zn nanocomposites exhibit different ion-capturing/releasing properties derived from opposite charges developed on them. This property not only declines the permeation of aggressive species into the coating matrix but also facilitates the release of divalent zinc ions or PDA through an on-demand manner when local corrosion initiates at the damaged zone. The propensity of PDA to anchor ferrous or ferric ions generated from anodic reactions in one hand and Zn (II) to form zinc hydroxide compounds at cathodic sites, on the other hand, endows the GO-PDA-Zn nanocomposite with high efficiency in reducing the corrosion current as measured by polarization and EIS analyses. More importantly, the outstanding self-healing function of GO-PDA/EP and GO-PDA-Zn/EP composite coatings was proved with impedance measurements on scratched coatings immersed in saline solution.

Ion Exchange of Benzoate in Ni-Al-Benzoate Layered Double Hydroxide by Amoxicillin

AbstractThe Ni-Al-NO3 layered double hydroxide (LDH) compound has been intercalated with benzoate anion through an anion exchange process for amoxicillin drug adsorption. The purpose of this research is to synthesize Ni-Al-NO3, ion exchange with benzoate anion to form Ni-Al-Benzoate, and then applying it as an adsorbent of amoxicillin. The adsorption process was carried out using the batch technique. The materials synthesized in this study were characterized by Fourier Transform Infrared Spectroscopy (FT-IR), X-ray ray diffraction (XRD), and Thermogravimetric Analysis/Differential Thermal Analysis (TGA/DTA). The exchange of benzoate in Ni-Al-Benzoate LDH by amoxicillin was followed by UV-Vis spectrophotometry. The pH, LDH amount, and contact time are optimized. The adsorption of amoxicillin by Ni-Al-Benzoate is fit to the pseudo-second-order kinetics model, with an adsorption capacity of 40 mg/ g. The results showed that anion exchange was successfully carried out between benzoate anion and amoxicillin.

Investigation on the interaction between theophylline and alkaline substances using the DAOSD approach

Abstract The interaction between theophylline and ethylenediamine, choline hydroxide and other alkaline compounds was investigated via UV–Vis spectroscopic method. Upon introduction of alkaline compounds, the π-π transition band of theophylline undergoes a red shift. This phenomenon is a result of removing a proton from the 7-position of a theophylline molecule. Moreover, cross peaks appear in 2D asynchronous spectra generated via the DAOSD approach on theophyllinate and various cation systems. These results suggest that cation-π interaction and cation-anion interactions occur between theophyllinate and various cations including ethylenediamine, choline, tetramethyl ammonium, K+ and Cs+. The interaction between anionic theophyllinate and various cation may play a considerable role in the transmembrane transport of theophylline in medicinal process.

Kinetika Adsorpsi Ion Besi (II) Oleh Biomassa Chaetoceros sp.

This research was done to study the adsorption kinetic of ferrous ionic by Chaetoceros sp. Many variables influenced the adsorption capacity of absorbent on ferrous ionic including interaction time, ferrous ionic concentration and pH. Two absorbens were used in this study i.e. pure culture and natural spoiled product called Diatomite/ Diatomae earth / Diatomaceous earth / Diatomooze of Chaetoceros sp. biomass. The adsorption capacity by biomass was measured by atomic absorption spectrophotometry method (AAS). The result showed that the adsorption process of two absorbents happened very fast. The time needed to get maximal adsorption were 10 and 15 minutes respectively. Adsorption pattern of two biomass can be interpreted by Langmuir and Freundlich isoterm showing monolayer. The adsorption capacity of Diatomite was five times higher than that of the pure culture biomass because it was influenced by surface group charge and wide surface area of porous. Acidity degree (pH) of solution determined surface active group charge and solubility of iron (II). The increased pH value, the biomass adsorption capacity was added because surface active group had negative charge. The adsorption of biomass was maximal around pH 5 while for pH higher than 5, it wasn’t significantly increased because the iron (II) formed insoluble hydroxide compound.