In Vitro Study on Combined Effect of Drugs for Hyperphosphatemia on Phosphorus Adsorption Capacity.

Phosphorus binders are often used in combination to produce synergistic effects. However, the synergistic effect may be affected by the change in pH or concomitant drugs. Nonetheless, the data on the adsorption capacities of these binders when used in combination with other binders are limited. In this study, we evaluated the adsorption capacity of phosphorus binders when used in combination. Precipitated calcium carbonate (CC), ferric citrate hydrate (FC), lanthanum carbonate hydrate (LC), and sucroferric oxyhydroxide (SO) were used as phosphorus binders. SO showed high adsorption capacity in the 1st and 2nd fluid, and the adsorption capacity of SO in combination with other binders was stable. In contrast, the adsorption capacities of CC + FC and FC + LC decreased in the 1st and 2nd fluid compared with that when used alone because of the release of citrate ions that chelate calcium or lanthanum ions. These results suggest that SO is less affected by interactions with other phosphorus binders and changes in pH and may be suitable for patients receiving concomitant drugs.

Effect of Concomitant Drugs on Sodium Zirconium Cyclosilicate Hydrate in Artificial Intestinal Juice.

To explore drug interactions involving sodium zirconium cyclosilicate hydrate (SZC) and concomitant drugs like calcium antagonists (amlodipine and nifedipine) and ß-blockers (carvedilol and bisoprolol), we investigate how these concomitant drugs influenced the administration of SZC in an artificial intestinal juice. Initially, we assessed the potassium ion adsorption capacity, ranking it as follows: calcium polystyrene sulfonate (CPS, 54.9 mg/g) < sodium polystyrene sulfonate (SPS, 62.1 mg/g) < SZC (90.8 mg/g). However, the adsorption equilibrium was achieved in the order of CPS ≒ SPS (within 1 min) < SZC (within 1 h). Subsequently, we determined the residual percentages of amlodipine, nifedipine, carvedilol, and bisoprolol, finding them to be 79.0-91.9% for SZC, 0.38-38.4% for SPS, and 0.57-29.0% for CPS. These results suggest the efficacy of SZC in managing hyperkalemia alongside concomitant drugs in an artificial intestinal juice, with particular emphasis on amlodipine (calcium antagonist) and carvedilol (ß-blocker). Additionally, we identified the presence of carbon, nitrogen, and oxygen components from both drugs on the SZC surface following interaction. We also evaluated how amlodipine, nifedipine, carvedilol, and bisoprolol affected the administration of SZC in the presence of potassium ions. Our results indicate that potassium ions and concomitant drugs did not interfere with each other in the artificial intestinal juice. These results offer valuable insights into the administration of SZC in conjunction with concomitant drugs. Lastly, the presented data shows qualitative results in this study.

Effect of Ointment Base on the Skin Wound-Healing Deficits in Streptozotocin-Induced Diabetic Rat.

Wound-healing deficits of the skin, one of the most common complications in patients with diabetes, delay wound healing, significantly reducing the patient's QOL. Therefore, the topical treatment of wound areas with drug-containing ointments and dressings is important. In this study, we investigated the effect of various ointment bases on skin wound healing in normal and streptozotocin-induced diabetic rats (STZ rats). Three ointment bases were used: white ointment (oil-based), absorbent cream (emulsion-based, w/o), and macrogol ointment (water-based). Skin wound healing in STZ rats was delayed compared with that in normal rats. Each of the three ointment bases was applied to the skin wound area in normal rats, and there was no difference in the therapeutic effect. The therapeutic effect of both white ointment and absorbent cream was higher in the STZ rats group than that in the non-treated group, and delayed wound healing was observed in STZ rats treated with macrogol ointment. In conclusion, skin wound healing in STZ rats is affected by the properties of the ointment base, and it is important to use an ointment base that controls the drying of the wound area in STZ rats. These findings provide information for the selection of ointment bases useful for application to skin wounds in patients with diabetes.

Evaluation of the Mechanism of Phosphate Removal Using Oyster Shell Powder in Aqueous Environments.

Eutrophication is caused by the inflow of nutrients, such as phosphorus and nitrogen, into closed waterbodies from wastewater. Calcination of oyster shells greatly increases their capacity for phosphate removal; however, information available on this mechanism and the capacity for phosphate removal under different initial pH values and temperatures is less. Herein, we investigated the utilization of oyster shells for phosphate removal under different pH and temperature conditions. Oyster shell powder (OSP) was calcined in a muffle furnace at temperature ranges of 200-1000 °C. Each OSP sample was added to a phosphate solution and the suspension was shaken under different pH and temperature conditions. The main component of OSP changed from CaCO3 to CaO after calcination at approx. 800 °C. The amount of phosphate removal by the calcined OSPs at 800 and 1000 °C was higher than that removal by the other OSPs. Further, the amount of calcium elution from the OSPs calcined at 800 and 1000 °C was higher than that elution from the other OSPs. This was because the solubility of CaO was higher than that of CaCO3. The amount of phosphate removal by the OSP and calcined OSPs at 200-600 °C was the highest at pH 5-7, and increased with increasing reaction temperature. These findings suggested that the mechanism of phosphate removal may involve adsorption in the OSP and OSPs calcined at 200-600 °C, whereas it is associated with coagulation settling and adsorption in the OSPs calcined at 800 and 1000 °C.

Potential Interaction between Sodium Polystyrene Sulfonate and Prescription Drugs in Artificial Intestinal Juice.

This study evaluated the interaction between sodium polystyrene sulfonate (SPS) and several commonly used concomitant drugs, such as carvedilol, bisoprolol, imidapril, atorvastatin and azilsartan. The residual rate of adsorption 6 h after starting the experiment followed the order carvedilol (0.36%) < bisoprolol (19.7%) < imidapril (81.2%) < atorvastatin (86.5%) < azilsartan (87.9%) in artificial intestinal juice (pH 6.8). In addition, the pKa of carvedilol and bisoprolol was 8.0 and 9.6 and that of atorvastatin, azilsartan, and imidapril was 4.5, 6.1, and 2.4, respectively. These results indicate that the form (ionic or uncharged) of each drug is important to its reaction with SPS. Moreover, we demonstrated the effect of potassium ions (concentration of 1000 or 2000 mg/L) on the adsorption of concomitant drugs onto SPS in artificial intestinal juice. Our results show that the residual rate of adsorption of carvedilol and bisoprolol increases with increasing concentration of potassium ions whereas adsorption of potassium ions onto SPS was unaffected by carvedilol and bisoprolol under our experimental conditions. Finally, the obtained results revealed that interactions between SPS and carvedilol or bisoprolol readily occur in artificial intestinal juice.

Application of Granulated Nickel-Aluminum-Zirconium Complex Hydroxide in the Flow Method for Recovery of Chromium(VI) Ions.

A colloidal silicate granulated nickel-aluminum-zirconium (CSG-NAZ) was prepared, and the chromium(VI) (Cr(VI)) ions recovery capacity was evaluated using a sodium sulfate solution in a column experiment. The amount adsorbed and breakthrough time were enhanced by decreasing the flow rate (flow rate is in the order of 3.0 > 2.0 > 0.5 mL). The breakthrough curves and model parameters were estimated using the Thomas and Yoon-Nelson models. The obtained data confirmed to fit both the Yoon-Nelson model (0.858-0.906) and the Thomas model (0.813-0.906). Additionally, Cr(VI) ions that adsorbed onto CSG-NAZ could be desorbed using a sodium sulfate solution in a column experiment. The total recovery percentage of Cr(VI) ions was 80.9% after six repetitions of adsorption/desorption. Finally, the obtained results revealed that CSG-NAZ was a candidate adsorbent for the recovery of Cr(VI) ions owing to its applicability toward a continuous system.

Characteristics of 21 Types of Tea Waste for Adsorbance of Ionic Dyes from Aqueous Solutions.

In this study, 21 tea types (six black, four green, three Oolong, two herb, and five medicinal) were used to remove ionic dye from wastewater, as they could be potential adsorbents for several ionic dyes without purification or activated treatment. The majority of the 21 teas could adsorb cationic (MB) and anionic (ORII) dyes, with greater suitability for cationic dyes, as well as BB54 and BR46. Black dye (KBla), a mixture of several dyes, was adsorbed to a high degree. The tea waste treatment resulted in chromaticity reduction of the dye solution and turbidity changes. Dye adsorption was greater at higher temperatures than lower ones, although the effect of temperature was not strong. The adsorptions fit the pseudo-second-order-model; therefore, they involved chemical adsorption. The tea waste had great potential for the adsorption of several types of dyes without purification or activated treatment, although the mechanisms are yet to be determined. Therefore, the physical properties and structural components of each tea type should be analyzed by comparing common or different features of tea types. Taken together, many types of tea that are consumed worldwide can be used for efficient adsorption of ionic dyes by application of the tea waste.

Recovery of Chromium(VI) Ions Using a Nickel-Aluminum-Zirconium Complex Hydroxide Based on Adsorption and Desorption Treatment.

In this study, we evaluate the desorption or recovery capacity of chromium(VI) ions using desorption solutions containing sodium hydroxide (NaOH) or sodium sulfate (Na2SO4). A complex hydroxide of nickel-aluminum-zirconium (NAZ) was prepared as the adsorbent for the removal of chromium(VI) ions. The results from repeated adsorption/desorption experiments on chromium(VI) ions using NAZ complex hydroxide were evaluated. The desorption percentage of chromium(VI) ions increased with the increase in the concentration of NaOH or Na2SO4 in the desorption solution. The determined optimal concentration of NaOH or Na2SO4 in the desorption solution was 10 mmol/L under the used experimental conditions. After three adsorption-desorption cycles, the recovery percentages of chromium(VI) ions using NaOH and Na2SO4 were 60% (total amounts adsorbed and desorbed were 102 and 61 mg/g, respectively) and 75% (total amounts adsorbed and desorbed were 96 and 72 mg/g, respectively), respectively. Additionally, we confirmed the existence of chromium on the surface of the NAZ complex hydroxide. After three adsorption/desorption cycles, the crystal structure of the NAZ complex hydroxide was maintained. These results indicated the potential of the NAZ complex hydroxide using a desorption solution containing NaOH or Na2SO4 for the recovery of chromium(VI) ions.

Fundamental Investigation of Adsorption Behavior onto Sodium Polystyrene Sulfonate to Potassium Ions and Its Concomitant Drugs in the Digestive Tract.

To verify the interaction between sodium polystyrene sulfonate (SPS) and its concomitant drugs, we elucidated the capability of potassium ions and concomitant drugs to adsorb onto SPS and the effect of their coexistence on the amount adsorbed. We identified 14 drugs used concomitantly with SPS from 2017-2019 in our investigation, and 5 drug preparations used in the clinical setting were used for the experiments. In the artificial intestinal juice, SPS adsorbed 39.05-69.77 mEq/g of potassium ions. Amlodipine besylate and nifedipine were well-adsorbed, while azosemide and febuxostat were did not adsorb well onto SPS. Our results and the results of a previous study suggest that additives in drug preparations affect the adsorption of drugs onto SPS. The adsorption kinetics onto SPS of drugs conformed to the pseudo-second order model. However, the adsorption of amlodipine besylate completely may not be fitted to the pseudo-second order model. The amount of amlodipine besylate adsorbed under the coexistence of potassium ions decreased compared to when potassium ions were absent. The amount of nifedipine and potassium ions adsorbed remained constant, regardless of whether potassium ions were present or not. These results might be due to the differences in their mechanisms of adsorption onto SPS and to the characteristics of the drugs. In a clinical setting, SPS is used concomitantly with various oral drugs. The interaction between SPS and its other concomitant drugs need to be elucidated more to obtain enough evidence for pharmacists to propose the appropriate prescription.

Optimization of the Hydrothermal Activation Treatment with Sodium Hydroxide Solution for the Conversion of Coal Fly Ash to Zeolite and Its Adsorption Capability of Lead (II) Ions from the Liquid Phase.

Coal fly ash (FA) was treated by hydrothermal activation with sodium hydroxide solution at different concentrations to optimize the conversion method. Zeolite of the sodium type is prepared from coal FA by 1, 1.5, and 3 mol/L sodium hydroxide solutions (ZE1, ZE1.5, and ZE3). These adsorbents' morphology, crystal structure, scanning electron microscopy, Fourier transform (FT)-IR spectra, cation exchange capacity (CEC), specific surface area and pore volumes, and pHpzc were determined. An adsorption experiment was performed to evaluate the effects of contact time, pH, temperature, and coexistence. From the results, the values of CEC and specific surface area of prepared samples was in the order ZE3 < ZE1.5 < ZE1. The similar trends were observed in lead ions adsorption. In addition, our obtained data elucidate that the ion exchange with sodium ions in the interlayer ZE1 is one of the adsorption mechanisms of Pb2+ from water layer. Finally, lead ions adsorbed on ZE1 could be desorbed using a hydrochloric acid solution, showing that ZE1 could be reused as a water purification agent.

Granulation of Nickel-Aluminum-Zirconium Complex Hydroxide Using Colloidal Silica for Adsorption of Chromium(VI) Ions from the Liquid Phase.

We combined a nickel-aluminum-zirconium complex hydroxide (NAZ) with colloidal silica as a binder to prepare a granulated agent for adsorbing heavy metals from aqueous media. Three samples with different particle diameters were prepared to evaluate the effects on the properties: small (NAZ-S), medium (NAZ-M), and large (NAZ-L). We confirmed the granulation of the prepared samples at a binder content of 25%. NAZ-S had the largest specific surface area and number of hydroxyl groups, followed by NAZ-M and then NAZ-L. Regarding the adsorption capacity, NAZ-S adsorbed the most chromium(VI) ions followed by NAZ-M and then NAZ-L. The binding energy of Cr(2p) at 575-577 eV was detected after adsorption, and the effects of the temperature, contact time, and pH on the adsorption of chromium(VI) ions were evaluated. We identified the following adsorption mechanism: ion exchange with sulfate ions in the interlayer region of the NAZ samples. Finally, the chromium(VI) ions adsorbed by the NAZ samples were easily desorbed using a desorption solution. The results showed that NAZ offers great potential for the removal of chromium(VI) ions from aqueous solutions.

Sustainable Downscaled Catalytic Colorimetric Determination of Manganese in Freshwater Using Smartphone-Based Monitoring Oxidation of 3,3',5,5'-Tetramethylbenzidine by Periodate.

A sustainable downscaled procedure using smartphone-based colorimetric determination of manganese (Mn(II)) was developed. This novel Mn(II) determination procedure is proposed using a simple, available microwell-plate platform and a smartphone as a detector. This approach is based on the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) by periodate using Mn(II) as a catalyst. The catalytic kinetics of Mn(II) under different conditions was investigated to determine the optimum condition where the different catalytic activities of various concentrations of Mn(II) evince. Under the optimum condition, the bluish-green product of oxidized TMB, proportioned to the concentration of Mn(II), was monitored using a smartphone camera, and the color signals were processed using ImageJ Software. The developed procedure showed great selectivity and sensitivity as linearity ranged from 1.8 × 10-6 to 4.6 × 10-5 M (0.1 to 2.5 µg/mL). The limits of detection and quantitation were 3.6 × 10-6 and 1.1 × 10-5 M (0.2 and 0.6 µg/mL), respectively. The determination of Mn(II) in freshwater samples was demonstrated to assess environmental water quality as an initial model to more easily promote water management according to the United Nations Sustainable Development Goals (UN-SDGs). The intensity of the red could be successfully applied to evaluate Mn(II) in canals and river water with no significant differences compared with the reference method of Inductively Coupled Plasma Optical Emission Spectrometry at a confidence level of 95%.

Improvement in adsorption of Hg2+ from aqueous media using sodium-type fine zeolite grains.

To increase the adsorption capability of Hg2+ from aqueous media, we prepared sodium-type fine zeolite grains with various particle sizes (denoted as ZE1, ZE2 and ZE3). The particle sizes of ZE1, ZE2 and ZE3 were 16.363 ± 0.365, 1.454 ± 0.357 and 0.607 ± 0.377 µm, respectively. Moreover, the CEC, specific surface area and pore volume were in the order ZE1 (42 mmol/g and 23.5 m2/g) < ZE2 (72 mmol/g and 67.1 m2/g) < ZE3 (135 mmol/g and 176.6 m2/g). Subsequently, the Hg2+ adsorption capability was investigated. The performance of tested agents on Hg2+ adsorbed was in the order ZE1 (5.0 mg/g) < ZE2 (9.4 mg/g) < ZE3 (20.2 mg/g). It was concluded that fine crystalline zeolite was important in enhancing the adsorption capability of Hg2+. In addition, the mechanism of adsorption of Hg2+ on the ZE samples was evaluated. Our results suggested that Hg2+ was exchanged with sodium ions in the interlayers of ZE samples with correlation coefficients of 0.966-0.979. Our findings revealed that these ZE samples constitute potential agents for the adsorption of Hg2+ from aqueous media.

Characteristics of Raw and Acid-Activated Bentonite and Its Application for Improving Electrical Conductivity of Tap Water.

This study aimed to investigate the characteristics of acid-activated bentonite by focusing on its capability of improving the quality of tap water used during wire electrical discharge machining. Raw bentonite (RB) was activated using sulfuric acid, nitric acid, and phosphoric acid solutions with concentrations of 1, 5, and 10 mol/L, respectively. Scanning electron microscopy images, specific surface area, pore volume, cation exchange capacity, X-ray diffraction patterns, and binding energy of RB and acid-activated bentonites were also evaluated. The specific surface area and pore volume of acid-activated bentonites exceeded those of RB. Conversely, the cation exchange capacity of acid-activated bentonites exhibited an opposite trend. The electrical conductivity of tap water was decreased significantly due to bentonite activated with sulfuric acid, nitric acid, and phosphoric acid solution (removal percentage of approximately 31-39%), as compared to that due to RB. Therefore, the relationship between electrical conductivity and the removed concentration of anion/cation ions was evaluated; the correlation coefficient was -0.950 for the experimental condition in this study. Additionally, the amount of magnesium, calcium, potassium, and sodium ions were decreased after the treatment. These results indicated that acid-activated bentonite can be produced from RB via acid activation and that it can be used to decrease electrical conductivity of tap water.

Exploiting the Different Parameters on the Adsorption of Phosphate Ions and Its Subsequent Recovery Using Complex Nickel-Aluminum-Zirconium Hydroxide.

In this study, the effect of contact time, temperature, pH, and coexistences on the adsorption of phosphate ions using the complex nickel-aluminum-zirconium hydroxide (NAZ) was evaluated. Moreover, the recovery of adsorbed phosphate ions from NAZ using desorption solution with different concentrations was demonstrated. The results showed that the quantity of phosphate ions adsorbed gradually increased with time, and the adsorption equilibrium was achieved within 24 h after adsorption. This kinetic data could be well described by the pseudo-second-order model with the correlation coefficient in the value of 0.997. Additionally, the quantity of phosphate which was adsorbed increased as temperature increased, and these results corresponded well with both the Langmuir, the correlation coefficient ranged from 0.920-0.949, and Freundlich models, the correlation coefficient ranged from 0.863-0.995. These results showed that the adsorption of phosphate ion was monolayer adsorption onto the NAZ surface. The optimal pH for removal of phosphate ions from aqueous media was during 4-8. In addition, chloride, nitrate, and sulfate ions did not significantly affect to the adsorption capability of phosphate ions in the complex solution system. Finally, the phosphate ions which were adsorbed onto NAZ could be recovered using sodium sulfate solution (recovery percentage: approx. 50% using sodium sulfate solution at 1000 mmol/L). These results highlight the potential of using NAZ as the cost-effectiveness adsorbent for phosphate ions removal from aqueous media.

Adsorption Performance on As(III) from Aqueous Solution Using the Complex Nickel-Aluminum Hydroxides.

In this study, complex nickel-aluminum hydroxides were prepared at different molar ratios (NA12, NA11, NA21, NA31, and NA41), and their adsorption capability on arsenic ions (As(III)) from aqueous media was assessed. The physicochemical properties such as morphology, X-ray diffraction pattern, specific surface area, numbers of hydroxyl groups, and surface pH were investigated. In addition, the effect of contact time, temperature, and pH on the adsorption capability on As(III) was also evaluated. NA41 exerted the highest adsorption capability on As(III) comparable to other prepared adsorbents. However, the specific surface area and numbers of hydroxyl groups did not significantly affect the adsorption capability on As(III). The equilibrium adsorption of As(III) using NA41 was achieved within 24 h, and the obtained results corresponded to a pseudo-second-order model with correlation coefficient value of 0.980. Additionally, the adsorption isotherms were well described by both the Langmuir and Freundlich equations. The optimal pH condition for removal of As(III) using NA41 was found to be approximately 6-8. Finally, the adsorption mechanism of As(III) was assessed by analyzing the binding energy and elemental distribution, which indicated that the electrostatic interaction and ion exchange influenced the adsorption of As(III) under experimental conditions. These results demonstrated the potential candidate of NA41 as an effective adsorbent on As(III) removal from aqueous media.

Energy-Dependent Endocytosis Is Responsible for Skin Penetration of Formulations Based on a Combination of Indomethacin Nanoparticles and l-Menthol in Rat and Göttingen Minipig.

We previously designed a Carbopol gel formulation (N-IND/MEN) based on a combination of indomethacin solid nanoparticles (IND-NPs) and l-menthol, and we reported that the N-IND/MEN showed high transdermal penetration. However, the detailed mechanism for transdermal penetration of IND-NPs was not clearly defined. In this study, we investigated whether endocytosis in the skin tissue of rat and Göttingen minipig is related to the transdermal penetration of IND-NPs using pharmacological inhibitors of endocytosis. The pharmacological inhibitors used in this study are as follows: 54 µM nystatin, a caveolae-mediated endocytosis (CavME) inhibitor; 40 µM dynasore, a clathrin-mediated endocytosis (CME) inhibitor; and 2 µM rottlerin, a micropinocytosis (MP) inhibitor. The N-IND/MEN was prepared by a bead mill method, and the particle size of solid indomethacin was 79-216 nm. In both rat and Göttingen minipig skin, skin penetration of approximately 80% IND-NPs was limited by the stratum corneum (SC), although the penetration of SC was improved by the combination of l-menthol. On the other hand, the treatment of nystatin and dynasore decreased the transdermal penetration of indomethacin in rats and Göttingen minipigs treated with N-IND/MEN. Moreover, in addition to nystatin and dynasore, rottlerin attenuated the transdermal penetration of IND-NPs in the Göttingen minipigs' skin. In conclusion, we found that l-menthol enhanced the SC penetration of IND-NPs. In addition, this study suggests that the SC-passed IND-NPs are absorbed into the skin tissue by energy-dependent endocytosis (CavME, CME, and/or MP pathways) on the epidermis under the SC, resulting in an enhancement in transdermal penetration of IND-NPs. These findings provide significant information for the design of nanomedicines in transdermal formulations.

Anthocyanin Profile, Antioxidant, Anti-Inflammatory, and Antimicrobial against Foodborne Pathogens Activities of Purple Rice Cultivars in Northern Thailand.

Five glutinous purple rice cultivars and non-glutinous purple rice cultivated in different altitudes in the north of Thailand were collected. The samples were extracted using ethanol and determined for anthocyanins using HPLC. The total phenolic content (TPC), total flavonoid content (TFC), and the antioxidant, anti-inflammatory, and antimicrobial activities against foodborne pathogens were investigated. The highland glutinous cultivar named Khao' Gam Luem-Phua (KGLP) extract had significantly high levels of cyanidin 3-O-glucoside, peonidin 3-O-glucoside, delphinidin 3-O-glucoside, TPC, and TFC, as well as exerting a potent antioxidant activity through ABTS assay (524.26 ± 4.63 VCEAC, mg l-ascorbic-ascorbic/g extract), lipid peroxidation (IC50 = 19.70 ± 0.31 µg/mL), superoxide anions (IC50 = 11.20 ± 0.25 µg/mL), nitric oxide (IC50 = 17.12 ± 0.56 µg/mL), a suppression effect on nitric oxide (IC50 = 18.32 ± 0.82 µg/mL), and an inducible nitric oxide synthase production (IC50 = 23.43 ± 1.21 µg/mL) in combined lipopolysaccharide-interferon-γ-activated RAW 264.7 murine macrophage cells. Additionally, KGLP also exhibited antimicrobial activity against foodborne pathogens, Staphylococcus aureus, Escherichia coli, Salmonella Enteritidis, and Vibrio parahaemolyticus. These results indicate that Thai glutinous purple rice cultivated on the highland could be a potent natural source of antioxidants, anti-inflammatories, and antimicrobial agents for use as a natural active pharmaceutical ingredient in functional food and nutraceutical products.

Characterization and Phosphate Adsorption Capability of Novel Nickel-Aluminum-Zirconium Complex Hydroxide.

In this study, the adsorption capability of phosphate ion using a novel tri-metals complex hydroxide was evaluated for preventing the eutrophication in water environment. A nickel-aluminum-zirconium complex hydroxide (NAZ) was synthesized using each inorganic sulfate mixing ratio of 0.9 : 1.0 : 0.1 and was calcined at different temperatures. The characteristics of the NAZ were analyzed by scanning electron microscopy images, X-ray diffraction analysis, elemental distribution, and binding energy. Moreover, the amount adsorbed of phosphate ion onto uncalcined and calcined NAZ was measured. That of phosphate ions onto the uncalcined was the largest of all. These results suggested that the adsorption of phosphate ions tends to depend on the physicochemical properties (e.g., amount of hydroxyl groups, pore volumes, and pH) of the adsorbents. Moreover, the adsorption mechanism of phosphate ions was evaluated on the basis of binding energy and elemental analysis. After adsorption, the binding energy of phosphorus P (2s and 2p) peaked and the sulfur peak intensity S(2s) reduced. This result indicated that the adsorption mechanism of phosphate would be exchanged with sulfate ions.

Adsorption of Phosphate Ions on Novel Mg/Fe/Al Hydroxides (MFA) Prepared at Different Mg2+/Fe3+/Al3+ Ratios.

In this study, we prepared novel Mg/Fe/Al hydroxides (MFA series: denoted by MFA1, MFA2, MF, and MA) and investigated their properties using scanning electron microscopy, X-ray diffraction, the specific surface area, and amount of hydroxyl groups. Additionally, the phosphate adsorption capabilities of the MFA series or Fe-Mg type hydrotalcites (FHT3.0 and FHT5.0) were evaluated by examining the effects of the solution pH and contact time, and analyzing the adsorption isotherm and desorption characteristics. In MFA1, a strong correlation exists between the amount of adsorbed phosphate ions and surface hydroxyl groups, with a correlation coefficient of 0.95. The adsorption kinetics data fitted using the pseudo-second-order model performs better than the pseudo-first-order model. The adsorption isotherm data were also fitted using both the Freundlich and Langmuir models. Finally, the phosphate ions adsorbed on the MFA1 surfaces were desorbed using sodium hydroxide solution. These results indicate that MFA1 offers great potential for phosphate ion adsorption from aqueous solutions and functions as a renewable adsorbent.