Liquid – Liquid Extraction and Pertraction of Eu(III) from Nitric Acid Medium Using Several Substituted Diglycolamide Extractants

Solvent extraction and supported liquid membrane (SLM) transport properties of Eu(III) from nitric acid feed conditions were investigated using several substituted diglycolamide (DGA) extractants such as N,N,N′N′-tetra-n-octyl diglycolamide (TODGA), N,N,N′N′-tetra(2-ethylhexyl) diglycolamide (T2EHDGA), N,N,N′N′-tetra-n-hexyl diglycolamide (THDGA), N,N,N′N′-tetra-n-pentyl diglycolamide (TPDGA), and N,N,N′N′-tetra-n-decyl diglycolamide (TDDGA). Effects of feed acidity and phase modifier composition on Eu(III) extraction were investigated using the DGAs and the nature of extracted species were ascertained by slope analysis method. The Eu(III) distribution ratio (D_Eu) values were found to decrease in the presence of iso-decanol. In general, the D_Eu values decreased with increased alkyl chain length of the DGA. The extracted species contained only 2 extractant molecules when TPDGA and TDDGA were used while for TODGA about four extractant molecules were found to be present in the extracted species.

The supported liquid membrane transport of Eu(III) was studied under varying experimental conditions using the five DGA extractants. Transport studies using 0.1 M DGA as the extractant suggested the trend as TDDGA > TODGA > T2EHDGA ～ THDGA which significantly changed to TPDGA > THDGA > TODGA > TDDGA > T2EHDGA in the presence of 30% iso-decanol as the phase modifier. The permeability coefficient (P) values were also determined with membranes of varying pore sizes.     

Studies on the Separation and Recovery of Palladium from Simulated High Level Liquid Waste (SHLW) Solution with Novel Extractant N,N,N′,N′-tetra (2-ethylhexyl) Dithiodiglycolamide DTDGA

The extraction properties of N,N,N',N'-tetra-(2-ethylhexyl) dithiodiglycolamide (DTDGA) have been evaluated for separation and recovery of palladium from simulated high-level liquid waste (SHLW) solution. Extraction of Pd was found to increase with increase in nitric acid concentration up to 4.0 M, above which the extraction remains almost constant. Acid uptake studies show 1:1 stoichiometry between DTDGA and HNO₃ at nitric acid concentration above 3.0 M. The acid uptake constant (K_H) was found to be 0.60 which could be due to the presence of two carbonyl groups of amidic moiety. DTDGA has shown very high extractability and selectivity for Pd over other metal ions present in SHLW. The separation factor (SF) for Pd over other metal ions was found to be more than 10⁴. Almost complete back extraction of palladium from organic phase was achieved with 0.01 M thiourea in 0.1 M nitric acid. Reusability studies of the extractant indicate that D_Pd remains almost constant even after five successive cycles of extraction and stripping. Two extraction stages will be required for complete extraction of 100 mg/L Palladium in 3.0 M nitric acid solution using 0.0025 M DTDGA/n-dodecane solvent system.     

Modification of Sodium Alginate for the Removal of Cd(II) from Aqueous Solutions

Sodium alginate was protonated using HCl in ethanol: H₂O mixture (30:70). The modified sodium alginate (MSA) was characterized by determination of carboxyl content and solubility percent. The modified sample acquires of 450 meq-COOH/100 g sample and exhibits the complete insolubility in water. The MSA was utilized as adsorbent material to remove Cd(II) ions from aqueous solutions. Factors affecting adsorption process, such as agitation time and adsorbent concentration and pH of the adsorbate, were examined. The adsorption data show that the maximum adsorption capacity, Q_max, of Cd(II) onto MSA is 769.23 mg/g. The adsorption data also showed that the adsorption of Cd(II) onto MSA obeys Langmuir and Freundlich isotherms.     

A High‐Yield,Liquid‐Phase Approach for the Partial Oxidation of Methane to Methanol using SO3 as the Oxidant

A direct approach for producing methanol from methane in a three‐step, liquid phase process is reported. In the first step, methane is reacted with SO₃ to form methanesulfonic acid (MSA) at 75 °C using a free‐radical initiator and MSA as the solvent. Urea‐H₂O₂ in combination with RhCl₃ is found to be the most effective initiator (57% conversion of SO₃; 7.2% conversion of CH₄). MSA is then oxidized by SO₃ at 160 °C in a second step to produce a mixture containing methyl bisulfate and some methyl methanesulfonate (87% conversion of MSA). In the third step, the mixture of methyl bisulfate and methyl methanesulfonate is hydrolyzed in the presence of an organic solvent, to produce an organic phase containing methanol and an aqueous phase containing sulfuric acid and some MSA (63% conversion of methyl bisulfate; 72% conversion of methyl methanesulfonate). Overall, 58% of the MSA (of which 23% is derived from methane) is converted to methanol.     

SPECTROPHOTOMETRIC INVESTIGATION OF THE ACIDITY CONSTANTS OF FLUORESCEIN IN VARIOUS WATER-ORGANIC SOLVENT MEDIA

We use a new procedure for estimating acid ionization constants of fluorescein using the spectrophotometric method at 25°C and at the constant ionic strength I = 0.1 M (KNO₃) in pure water as well as in aqueous media containing variable percentages (10–50% w/v) of organic solvents. The used organic solvents were methanol, ethanol, N,N-dimethyl formamide, dimethyl sulfoxide, acetonitrile, and dioxane. The obtained results indicated that acidity constants decrease as the content of an organic solvent in the medium increases. The acidity constants of all related equilibria are estimated using the whole spectral fitting of the collected data. The DATAN program was applied for determination of acidity constants. The effects of various solvents on absorption properties and acidity constants of each component are also discussed.     

Electrodeposition of nanocrystalline copper thin films from 1-ethyl-3-methylimidazolium ethylsulphate ionic liquid

Copper thin films are increasingly important as interconnectors for the creation of smaller and better performing integrated circuits and electrodeposition from ionic liquid-based electrolytes could provide a greener fabrication method for these films. The electrodeposition of copper from copper(I) and copper(II) salt solutions in a low cost, widely available ionic liquid, 1-ethyl-3-methylimidazolium ethylsulphate, was studied using a range of different deposition potentials and temperatures. Three different electrolytes containing ~0.1 M of copper(I) chloride(CuCl), copper(II) chloride (CuCl₂) and copper(II) sulphate (CuSO₄) were used. Under similar deposition conditions, the films obtained from CuCl and CuSO₄-based electrolytes presented better continuity than films obtained from CuCl₂-based electrolyte. Continuous films with a homogeneous structure were obtained by electrodeposition from CuCl and CuSO₄-based solutions at a constant potential of ?1.8 V and a temperature of 35 °C. Under similar deposition parameters, the films deposited from CuCl₂-based electrolyte presented the largest particle size, while those deposited from copper(I) chloride and CuSO₄-based solutions presented finer microstructures. X-ray diffraction analysis and energy dispersive X-ray spectroscopy showed that the deposits were crystalline and consisted mainly of copper, with traces of oxygen and sulphur resulting from residues of the ionic liquid. The films presented a nanocrystalline microstructure consisting of particles about 25 nm, aggregated in clusters.     

Effect of Extraction Solvent on Oil and Bioactives Composition of Commercial Indian Niger (Guizotia abyssinica (L.f.) Cass.) Seed

Commercially available niger (Guizotia abyssinica (L.f.) Cass.) seed was investigated to evaluate the effect of extraction solvent on oil and bioactives composition. For this purpose, niger seeds were subjected to solvent extraction using solvents of different polarity, viz., hexane, petroleum ether, chloroform, acetone, methanol and ethanol. The oil content of niger seeds obtained after extraction with solvents of different polarities was in the range of 31.8–41.3 g/100 g. The extracted oil was characterized by the following parameters: color (40.0–95.0 Lovibond units), free fatty acids (3.6–12.3 g/100 g), peroxide value (3.2–7.8 mequiv O₂/kg), iodine value (137.6–140.3 cg I₂/g), saponification value (177.3–185.9 mg KOH/g) and unsaponifiable matter (1.3–4.3 g/100 g). Among fatty acids, linoleic acid (69.4–73.2 %) was the major fatty acid and trilinolein (31.2–33.4 %) was the major triacylglycerol. The composition of bioactive molecules was 171.9–345.8 ppm of total tocopherols; 247.1–2,647.7 ppm of total phenolics; 1,249.6–6,309.3 ppm of total sterols and 18.9–181.0 ppm of total carotenoids. Among the tocopherols, α-tocopherol was the major component with 154–276 ppm. Of the total phenolics, vanillic acid with 176–1,709 ppm was the major phenolic compound in the oil extracted using different solvents. Ethanol-extracted oil showed a 13.9-fold better oxidative stability and a higher radical scavenging activity (IC₅₀ value of 9.2 mg/mL) compared to hexane-extracted oil (IC₅₀ value of 40.3 mg/mL). This is probably the first report of its kind on solvent extractability of bioactives of niger seed.     

Surface modification of black tea waste using bleaching technique for enhanced biosorption of Methylene blue in aqueous environment

ABSTRACT

In the current study, the bleaching technique with sodium hypochlorite (NaOCl) was used to modify black tea waste (BTW) for enhancing its biosorption performance of Methylene blue (MB) dye. Fourier transform infrared (FT-IR), scanning electron microscopy (SEM), (thermogravimetric-differential thermal analysis) TG/DTA, X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) analysis and surface acidity and pH_pzc measurements were employed to determine the textural structure and surface chemistry of the raw and NaOCl-modified BTW. The results indicate that after using bleaching modification, the MB biosorption capacity of BTW was enhanced approximately threefold. Maximum biosorption capacities were found as 125 mg g^?1 for BTW and 416.67 mg g^?1 for bleached black tea waste (BBTW).     

Regeneration of Mixed Solvent by Ion Exchange Resin: Selective Removal of Chloride and Sulfate

Abstract

The selective extraction of sulfate and chloride ions from mixed solvent solutions was investigated. The mixed solvents consisted of water and 50 to 100%‐w (salt‐free solvent) ethylene glycol. The extraction was measured for mixed solvent solutions containing only sulfate and chloride, and mixed solvent solutions saturated with trona (sodium sesquicarbonate, Na₂CO₃ · NaHCO₃ · 2H₂O(s). Three anion exchange resins, Dowex 1X8‐50, Dowex 21K‐Cl, and Dowex MSA‐1, were investigated for their chemical and physical resistance to the mixed solvent carbonate/bicarbonate solutions, for their swelling behavior in the different mixed solvents, and for their extraction efficiency for chloride and sulfate.

The loading of the ion exchangers was fitted to a Langmuir‐type sorption model. While the extraction from trona‐free mixed solvents was well reproduced, the loading of the ion exchangers with chloride and sulfate from trona‐saturated mixed solvent solutions did not fit the sorption model. It appears, rather, that under these conditions chloride and sulfate are “salted out” of the bulk solution and driven into the ion exchangers.     

Impregnated of C6CoFeN6 nanoparticles in poly-1-naphthol for uptake of Cs(I) from aqueous waste

To carry out our research, C₆CoFeN₆@poly-1-naphthol nanoparticles were synthesized and characterized by SEM, X-ray diffraction, Fourier transform infrared, thermogravimetric analysis and Brunauer–Emmett–Teller (BET) analyses. The SEM images indicate that the average particle sizes are about 60 nm in diameter. The BET result provides a clear evidence for the high surface area of the sample 180.6 m²/g. Cs(I) ions removed from the aqueous solution in a batch mode using CoHCF@poly-1-nanphtol as an adsorbent. The adsorption effecting parameters such as the solution pH, initial Cs(I) concentration, contact time and temperature were studied. Maximum sorption capacity for the nanocomposite was found to be 200.5 mg/g at 1000 mg/g, pH = 5 and 298 K. The time-adsorption dependence studies indicated that the maximum Cs(I) uptake was within the initial 40 min contact time and the adsorption mechanism was governed by the double exponential model. The equilibrium sorption data fitted well to the Freudlich model with n ? 1 indicating a stronger interaction and high affinity of C₆CoFeN₆@poly-1-naphthol for Cs(I) ions. The thermodynamic parameters, including changes in Gibbs free energy, entropy and enthalpy, were determined. The results indicated that CoHCF–poly-1-nanphtol could be a potential adsorbent for the uptake of Cs(I) ions from an aqueous solution.     

Treatment of flue gas desulfurization wastewater with near-zero liquid discharge by nanofiltration-membrane distillation process

The treatment process for flue gas desulfurization (FGD) wastewater was investigated using an integrated nanofiltration–membrane distillation (NF-MD) technology for near-zero liquid discharge. The whole system could achieve over 99.99% salt rejection ratio and over 92% of water reclamation ratio. The salinity of the MD permeate was low (Cl^- less than 3 mg/L and SO₄^2- less than 1 mg/L) and the permeate could be reused by thermal power plants directly. High-purity (over 97%) brine (10% NaCl, w/w) was produced after MD concentration. It was found that chemical softening and NF pretreatment could decrease MD membrane scaling significantly. No wastewater was discharged during the whole process. Such hybrid NF-MD system has the potential for practical application in FGD wastewater treatment.     

Investigation of poly(methyl acrylate) grafted chitosan as a polymeric drug carrier

The graft copolymerization of methyl acrylate (MA) onto chitosan in aqueous medium was investigated using potassium persulfate (KPS) as initiator. The grafting conditions were optimized by studying the effects of the polymerization variables (the initiator concentration, the ratio of monomer to chitosan, and reaction temperature) on the percentage of grafting (PG). PG was found to depend on these variables, and the highest grafting percentage (256 %) could be obtained at chitosan = 1 g, KPS = 4.5 × 10^?3 M, methyl acrylate monomer = 6 g, T = 60 °C and t = 180 min. The graft copolymer was characterized by Fourier transform infrared spectra analysis, thermogravimetry (differential thermogravimetry, differential scanning calorimetric), X-ray powder diffraction as well as CP-MAS ¹³C NMR spectroscopy. These analyses are highly confirmed the formation of poly(methyl acrylate) grafted chitosan (PMAGC). Furthermore, the gelation of the grafted polymers (PG 68, 122, 218 and 256 %) in distilled water has been studied, and the results revealed that the percentage of swelling number increase with increasing PG of the polymers. Controlled release of niacin (vitamin B₃) from the hydrogel of the grafted polymers (PG 68, 122 and 256 %) in aqueous medium has been studied using ultraviolet absorption to follow quantities released at different times (for each experiment: PMAGC 100 mg, niacin 2.46 mg, distilled water 100 ml). The study was repeated again with same conditions except the using of 4.92 mg of niacin instead of 2.46 mg (PG of the grafted polymer is 256 %). The diffusion coefficient (D, cm²/h) of niacin from the hydrogel of the grafted polymer (PG 256 %) was calculated depending on Higuchi model (diffusion coefficient of the first load is 0.00194 cm²/h while 0.00255 cm²/h of the second load).     

The Synthesis and Characterization of New Schiff Bases and Investigating them in Solvent Extraction of Chromium and Copper

New Schiff bases containing nitrogen, sulfur and oxygen donor atoms, were designed and synthesized in a multi—step reaction sequence. The Schiff base(I) was used in solvent extraction of metal chlorides such as Cu(II) from aqueous phase to the organic phase. The influences of the parameter functions, such as pH, solvent, ionic strength of aqueous phase, aqueous to organic phase, and concentration of the extractant were investigated to shed light on their chemical extracting properties upon the extractability of metal ions. The effect of chloroform, dichloromethane, and nitrobenzene as organic solvents over the metal chlorides extraction was investigated at 25 ± 0.1°C by using flame atomic absorption and the result is that the ability of extraction in solvents as follows C₆H₅NO₂ > CHCl₃ > CH₂Cl₂.     

Micro-Capacitor Behavior of Poly(3-Hexyl Thiophene)/Carbon Fiber/Electrolyte System and Equivalent Circuit Model

In this article, 3-Hexyl thiophene (3HTh) monomer was electrocoated on carbon fiber micro electrode (CFME) to study electrochemical impedance spectroscopic (EIS) analysis. Poly(3HTh)/CFME is characterized by Cyclic voltammetry (CV), Fourier transform infrared reflectance-attenuated total reflection spectroscopy (FTIR-ATR), Scanning electron microscopy-Energy Dispersive X-ray analysis (SEM-EDX), and electrochemical impedance spectroscopy (EIS). The effects of different monomer concentrations (0.5, 1.0 and 1.5 mM) on polymer were reported in 0.1 M tetraethyl ammonium tetrafluoroborate (TEABF₄)/acetonitrile (ACN) solution. The highest low frequency capacitance (C_LF = 1.394 mF cm^?2) was obtained for [3HTh]₀ = 0.5 mM. The equivalent circuit model of R(QR(CR)(RW))(CR) was examined for polymer/electrolyte system.     

Phase transformation on bone cement: Monocalcium phosphate monohydrate into calcium-deficient hydroxyapatite during setting

This study evaluated the phase transformation of calcium phosphate cement (CPC) using a mixture of monocalcium phosphate monohydrate (MCPM) and CaCO₃ as the solid phase and either water or a sodium phosphate buffer (SPB) solution (pH=7.0) as the liquid phase. The synthetic CPC was characterized by X-ray diffraction (XRD) analysis and transmission electron microscopy (TEM). The setting reaction in the SPB solution involved three phase transformations. Firstly, MCPM and CaCO₃ reacted with sodium phosphate immediately to form dicalcium phosphate dehydrate (DCPD) which continued to dissolve. Secondly, meanwhile, an intermediate amorphous calcium phosphate (ACP) was formed. Finally, ACP transformed into calcium-deficient hydroxyapatite (CDHA). In contrast, the reaction stopped at the first stage in water. Consequently, the SPB solution not only caused the dissolution of DCPD but also provided the buffering capacity to induce the conversion of the starting materials to CDHA.     

Hydrothermal synthesis of an ITH-type germanosilicate zeolite in a non-concentrated gel system

A germanosilicate zeolite with the ITH framework type (designated JLG-18) has been hydrothermally synthesized. Compared with other ITH-type materials synthesized in concentrated systems, JLG-18 was the first one synthesized in a non-concentrated system. In addition, the organic structure-directing agent (OSDA) for the synthesis of JLG-18 was N,N,N′,N′-tetramethyl-1,6-hexanediamine (TMHDA), which was less expensive than those used for the synthesis of other ITH-type materials. The optimal molar ratio of the initial gel was 0.5 SiO₂: 0.5 GeO₂: 7 TMHDA: 1.4 HF: 42 H₂O. The effects of various synthetic parameters on the formation of final products, such as source materials, GeO₂:SiO₂ ratio, H₂O:(SiO₂ + GeO₂) ratio, TMHDA:(SiO₂ + GeO₂) ratio, crystallization temperature, and reaction time, were investigated. The as-synthesized samples were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), inductively coupled plasma (ICP), elemental analysis, thermogravimetric analysis (TG), and N₂ adsorption. JLG-18 with a Si:Ge ratio of 2:1 exhibited excellent thermal stability, even after calcination at 700 °C in air. The microporous surface area of JLG-18 was 317.07 m²/g.     

Electrolyte type and concentration effects on poly(3-(2- aminoethyl thiophene) electro-coated on glassy carbon electrode via impedimetric study

In this study, 3-(2-Aminoethyl thiophene) (2AET) monomer was electropolymerized on glassy carbon electrode (GCE) using various electrolytes (lithium perchlorate (LiClO₄), sodium perchlorate (NaClO₄), tetrabutyl ammonium tetra fluoroborate (TBABF₄) and tetraethyl ammonium tetra fluoroborate (TEABF₄) in acetonitrile (CH₃CN) as solvent. Poly(3-(2-aminoethyl thiophene) (P(2AET))/GCE was characterized by cyclic voltammetry (CV), Fourier transform infrared reflectance spectrophotometry (FTIR-ATR), scanning electron microscopy, energy dispersive X-ray analysis (EDX), and electrochemical impedance spectroscopy (EIS) techniques. The electrochemical impedance spectroscopic results were given by Nyquist, Bode-magnitude, Bode-phase, capacitance and admittance plots. The highest low frequency capacitance (C _LF) value obtained was 0.65 mF cm^?2 in 0.1 M LiClO₄/CH₃CN for the initial monomer concentration of 1.5 mM. The highest double layer capacitance (C _dl = ~0.63 mF cm^?2) was obtained in 0.1 M LiClO₄/ACN for [2AET]₀ = 0.5, 1.0 and 1.5 mM. The maximum phase angles (θ = 76.1^o at 26.57 Hz) and conductivity (Y″ = 3.5 mS) were obtained in TEABF₄/ACN for [2AET]₀ = 0.5 and 1.0 mM, respectively. An equivalent circuit model of R(Q(R(Q(R(CR))))) was simulated for different electrolytes (LiClO₄, NaClO₄, TBABF₄ and TEABF₄)/P(2AET)/GCE system. A good fitting was obtained for the calculated experimental and theoretical EIS measurement results. The electroactivity of P(2AET)/GCE opens the possibility of using modified coated electrodes for electrochemical micro-capacitor electrodes and biosensor applications.     

Polyamides containing quinoxaline moiety

A new quinoxaline moiety containing aromatic diamine; 2,3-bis[4-(4-aminophenoxy)phenyl]quinoxaline (APQ) was synthesized starting from 4-methoxybenzaldehyde and was characterized by IR, ¹H, ¹³C NMR and Mass spectrometry. Five new polyamides were synthesized by polycondensation of various aliphatic diacid / aromatic diacids namely, azelaic acid, bis(4-carboxyphenyl)dimethylsilane, 4,4′-oxybis(benzoicacid), isophthalic acid and terephthalic acid with APQ by Yamazaki’s phosphorylation method using triphenyl phosphite as condensing agent. The polyamides were characterized by IR spectroscopy, solubility tests, inherent viscosity, X-ray diffraction technique, differential scanning colorimetry and thermogravimetric analysis. The polyamides had inherent viscosities in the range 0.39–0.45 dL/g in N, N-dimethylacetamide at 30?±?0.1?°C. The polyamides were soluble in polar aprotic solvents such as N, N-dimethylacetamide, N, N-dimethylformamide, dimethylsulfoxide, N-methylpyrrolidone. X-Ray diffraction studies showed that polyamides were amorphous in nature. The polyamides showed glass transition temperatures in the range 104–205?°C, according to differential scanning calorimetry. Thermogravimetric analysis exhibited initial decomposition temperatures above 348?°C; indicating that these polyamides possessed excellent thermal stability.     

Investigation of Oleuropein Content in Olive Leaf Extract Obtained by Supercritical Fluid Extraction and Soxhlet Methods

The separation processes of the phenolic compounds from solid plant matrixes are of great importance. In the scope of developing more efficient methods to separate olive leaf extract, dried and ground olive tree leaves from Aegean region of Turkey were extracted by means of Soxhlet and supercritical fluid extraction (SFE) methods. In the Soxhlet method, different types of solvents (hexane, water, ethanol, methanol, and methanol/hexane (3:2, v/v) mixture) were used to determine the effect of the solvent type on the extraction performance. In the SFE method, the effect of pressure (100–300 bar), temperature (50 and 100°C), and type of co-solvent on the amount of both extract and oleuropein were investigated. Ethanol, methanol and water were selected as co-solvent in 20% (v/v) amount. Quantitative analysis was performed by using a liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) technique. The results of SFE were compared with those obtained by the Soxhlet method. Whereas the highest oleuropein yield was achieved via the Soxhlet method through methanol with the value of 37.84 mg/g dried leaf, the best oleuropein yield was achieved with the value of 14.26 mg/g dried leaf by using CO₂ modified by methanol at 300 bar and 100°C in the SFE method.     

Adsorption Behaviors of Platinum Group Metals in Simulated High Level Liquid Waste Using Macroporous (MOTDGA-TOA)/SiO2-P Silica-based Absorbent

As fundamental research for separation of platinum group metals (PGMs) from high level liquid waste (HLLW) by macroporous silica-based adsorbent, (MOTDGA-TOA)/SiO₂-P adsorbent was prepared by impregnation of N,N′-dimethyl-N,N′-di-n-octyl-thiodiglycolamide (MOTDGA) and Tri-n-octylamine (TOA) into silica/polymer composite support (SiO₂-P). The adsorption behavior of Ru(III), Rh(III), and Pd(II) in simulated HLLW onto the adsorbent were investigated by the batch method to obtain their corresponding equilibrium and kinetic data. The adsorbent showed strong adsorption for Pd(II) and the adsorption reached equilibrium within 2 hr. High distribution coefficient (K _d) values for Pd(II) were obtained in 0.1–1 M HNO₃ concentration. In addition, the use of both MOTDGA and TOA improved adsorption of Ru(III) and Rh(III) better than individual use of them. Especially, the K _d value for Ru(III) towards (MOTDGA-TOA)/SiO₂-P adsorbent was three times larger than that in the adsorption using only with MOTDGA or TOA as extractant. The adsorptions of Ru(III), Rh(III), and Pd(II) followed the Langmuir adsorption model, and were found to be controlled by the chemisorption mechanism.