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The separation and isolation of many of the platinum group metals (PGMs) is currently achieved commercially using solvent extraction processes. The extraction of rhodium is problematic however, as a variety of complexes of the form [RhCln(H2O)6‐n](n−3)− are found in hydrochloric acid, making it difficult to design a reagent that can extract all the rhodium. In this work, the synergistic combination of a primary amine (2‐ethylhexylamine, LA) with a primary amide (3,5,5‐trimethylhexanamide, L1) is shown to extract over 85 % of rhodium from 4 M hydrochloric acid. Two rhodium complexes are shown to reside in the organic phase, the ion‐pair [HLA]3[RhCl6] and the amide complex [HLA]2[RhCl5(L1)]; in the latter complex, the amide is tautomerized to its enol form and coordinated to the rhodium centre through the nitrogen atom. This insight highlights the need for ligands that target specific metal complexes in the aqueous phase and provides an efficient synergistic solution for the solvent extraction of rhodium., A synergistic combination of a simple primary amine (LA) and a simple primary amide (L1) is shown to extract rhodium from hydrochloric acid. A range of experimental and computational techniques are used to elucidate the structures of two different complexes in the organic phase; the ion‐pair [HLA]3[RhCl6] and the amide complex [HLA]2[RhCl5(L1)]. In the latter complex, the amide is tautomerized to its enol form and coordinated through the nitrogen atom.

In this work, the aqueous speciation of Rh(III) in chloride medium was investigated by UV-vis spectroscopy for ligand to metal ratios R = (Cl&minus, )/(Rh) ranging from 300 to 5000, at fixed Rh concentration (2.4 &times, 10&minus, 3 M). Under the chemical conditions of this work, no time evolution was observed, which allows for the fitting of the UV-vis data by Principal Component Analysis (PCA) and Multi-Curve Resolution (MCR). From this, and by comparison with literature data, the three independent species [RhCl4]&minus, [RhCl5]2&minus, and [RhCl6]3&minus, were identified, their individual absorption spectra derived and their respective contribution to the collected experimental UV-vis spectra calculated. Then, extraction of Rh(III) towards the ionic liquid trihexyltetradecylphosphonium chloride was performed. Comparison with the speciation data gives insight into the extraction mechanism and the extracted species.

06.03.2018 tarihli ve 30352 sayılı Resmi Gazetede yayımlanan “Yükseköğretim Kanunu İle Bazı Kanun Ve Kanun Hükmünde Kararnamelerde Değişiklik Yapılması Hakkında Kanun” ile 18.06.2018 tarihli “Lisansüstü Tezlerin Elektronik Ortamda Toplanması, Düzenlenmesi ve Erişime Açılmasına İlişkin Yönerge” gereğince tam metin erişime açılmıştır. Bu çalışmada Pd (II) ve Rh (III) metallerinin klor iyonu içeren sulu çözeltilerdeki tanin, gallik asit ve pirogallolden üretilen polifenolfenol ? formaldehit kondensasyonu ile üretilen üzerinde adsorpsiyonu incelenmiştir. Polifenol reçineleri 13,3 N NH3 katalizörlüğünde kütlece %37'lik formaldehit kondenzasyonu ile üretilmiştir. Elde edilen bu reçinelerinin FTIR spektroskopisi ile karakterizasyonu yapılmıştır. Kondenzasyonun metilen ve di-metil eter köprüleri yolu ile iki şekilde gerçekleşmesi mümkündür. Reaksiyonun iki adımlı bir mekanizması vardır: Birinci adımda, elektrofilik aromatik sübstitüsyon reaksiyonu olan fenol halkasına metil bağlnamsı; ikinci adımda ise, kondenzasyon reaksiyonudur.Polifenol reçineleri üzerinde Pd (II) ve Rh (III) adsorpsiyonu kesikli adsorpsiyon sistemi kullanılarak gerçekleştirilmiştir. İsotermler, 1g polifenol reçinesi, 1 L metal çözeltisi kullanılarak gerçekleştirildi. Pd (II) başlangıç konsantrasyonu 20 ? 150 mg/L, Rh (III) başlangıç konsantrasyonu ise 15 ? 90 mg/L arasında değişen konsantrasyonlarda çalışılmıştır. Adsorpsiyon süresinin, başlangıç pH ve Cl- iyonu konsantrasyonunun, adsorban miktarının, sıcaklığın ve başlangıç metal konsantrasyonlarının adsropsiyona etkisi incelenmiştir. Adsorpsiyon dengesine ulaşmak için gerekli süre 120 dakikadır. Deneysel izoterm verileri Langmuir, Tempkin, Dubinin-Radushkevich ve Redlich-Peterson eşitlikleri kullanılarak analiz edilmiştir. Pd (II) ve Rh (III)'nin polifenoller üzerindeki adsorpsiyonu Langmuir izotermine uyum göstermektedir. Tek tabaka adsorpsiyon kapasiteleri her bir reçine için belirlenmiştir. ? Ho, ? So and ? Go gibi termodinamil parametreler hesaplanmıştır. Deneysel veriler adsorsiyon kinetiğini belirlemek üzere psödo birinci mertebe, psödo ikinci mertebe, Elovich ve partikül içi difüzyon eşitlikleri kullanılara incelenmiş ve Pd (II) ve Rh (III)'ün psödo ikinci mertebe adsorpsiyon kinetik eşitliğine uyduğu belirlenmiştir. Aynı zamanda muhtemel adsorpsiyon mekanizması önerilmiştir. Pd (II) ve Rh (III) polifenol reçneleri üzerinde adsorplandıktan sonra metalik Pd ve Rh'a dönüşmektedir. Bu, adsropsiyon sırasında, kloro paladyum (II) ve kloro rodyum (III) reçine yüzeyinde bulunan hidroksil grupları ile redoks tepkimesi vererek Pd (0) ve Rh (0)'a indirgenmesi yoluyla gerçekleşmektedir. PdCl2(H2O)2 ve PdCl(H2O)3+ gibi düşük klor iyonu içeren Pd (II) türleri daha çok reçine tarafından tercih edilmektedir. Rh (III)'ün [RhCl_5 H_2 O]^(2-) ve [RhCl_2 (H_2 O)_4 ]^- türleri sulu çözeltiden adsorplanmıştır. Adsorpsiyon sonrasında SEM fotografı, XRD ve EDS desenleri alınarak tartışılmıştır Tek kademeli adsorpsiyon sistemi farklı adsorban kütlesi ve değişen hacimlerde Langmuir izotermi kullanılarak dizayn edilmiştir. In this study, polyphenols such as valonia tannin, gallic acid and pyrogallol, and formaldehyde condensation reaction has been investigated. Polyphenol resins were prepared by NH3 solution (13.3 N) and formaldehyde (37 %wt). Polyphenol resins, obtained from condensation reaction, were characterized by FTIR spectroscopy. There are two possible condensation reaction paths for the reaction of polyphenols and formaldehyde, leading to the formation of a methylene bridge. The first step for two mechanisms, methylolation, is an electrophilic aromatic substitution reaction. The second step is a condensation reaction. The adsorption of palladium and rhodium onto polyphenol resins were studied using a batch adsorber. The isotherms were determined by mixing 1 g polyphenol resin, with 1 L of metal solution of initial concentrations from 20 to 150 mg/L for palladium and from 15 to 90 mg/L for rhodium. The effects of contact time, initial pH, initial Cl- concentration, adsorbent dose, temperature and initial metal concentration on the palladium and rhodium adsorption by the polyphenol resin have been studied. A contact time of 120 min was required to achieve equilibrium. The experimental isotherm data were analyzed using the Langmuir, Freundlich, Tempkin, Dubinin-Radushkevich and Redlich-Peterson equations. Adsorption of palladium and rhodium onto polyphenol resin followed the Langmuir isotherm. The monolayer adsorption capacities of each resin were determined and discussed. The thermodynamic parameters, such as ? Ho, ? So and ? Go, were also determined and evaluated. The experimental data were analyzed using four adsorption kinetic models - the pseudo first- and second-order equations, the Elovich equation and intraparticle diffusion equation ? to determine the best fit equation for the adsorption of palladium and rhodium onto polyphenol resins. The characteristic parameters for each kinetic models have been determined and the correlation coefficients have been calculated in order to assess which model provides the best fit predicted data with experimental results. Results show that the pseudo second-order equation provides the best correlation for the adsorption process. Adsorption mechanism was also proposed for the adsorption of palladium and rhodium onto polyphenol resins. It was found that Pd (II) and Rh (III) was adsorbed onto the polyphenol particles as a reduced metallic Pd and Rh through redoxreaction mechanism: chloropalladium (II) and aqua chloro rhodium (III) species were reduced to Pd (0), while hydroxyl groups of polyphenol resin were oxidized during the adsorption. Additionally, it was observed that Pd (II) species containing fewer Cl, such as PdCl2(H2O)2 and PdCl(H2O)3+, were more favorable for the adsorption than PdCl3(H2O)- and PdCl42-. Rh (III) species [RhCl_5 H_2 O]^(2-) and [RhCl_2 (H_2 O)_4 ]^- adsorbed onto polyphenol resin surface. By utilizing such characteristics of polyphenol resin particles, it is expected that they can be applied to recover Pd (II) and Rh (III) efficiently and simply with low cost. A single stage batch adsorber was designed for different adsorbent mass/treated effluent volume ratios using the Langmuir isotherm.