Mehmet Hakan Morcali

Silver Recovery from Waste Radiographic Films by Cementation and Reduction

Abstract Waste radiographic films can act as potential source materials for the recovery of valuable silver. In this study, a chemical processing scheme was adopted to recover silver metal from waste radiographic films. The films were dissolved in 1 M nitric acid (HNO3) solution for 3 hours at 70°C to convert silver into silver nitrate (AgNO3(aq)). Subsequently, the silver nitrate solution was treated using two different methods. The first involved cementation with fine iron powder and with fine zinc powder. These two well-known cementators were compared to each other with respect to purity of the final product and the recovery efficiency. The second method was sodium hydroxide (NaOH) precipitation. The treatment with Fe powder and Zn powder resulted in the formation of metallic silver powder in just one step. Ag2O obtained via NaOH precipitation was then treated using two different methods: a treatment with a mixture of glucose (C6H12O6) and NaOH to yield metallic silver and a heat treatment, in which Ag2O was converted to silver metal at 500°C. TGA analysis revealed that at 400°C Ag2O decomposes into silver and oxygen. With the exception of the powder produced by glucose reduction, all the powders would easily find industrial application. In addition, by using relatively inexpensive chemicals these applied processes show promise for further scaling up.

Platinum uptake from chloride solutions using biosorbents

Present work investigates platinum uptake from synthetically prepared, dilute platinum-bearing solutions using biomass residues, i.e. pistachio nut shell and rice husk, which are abundant in Turkey, and provides a comparison between these two biosorbents. Effects of the different uptake parameters, sorbent dosage, contact time, temperature and pH of solution on platinum uptake (%) were studied in detail on a batch sorption. Before the pistachio nut shell was activated, platinum uptake (%) was poor compared to the rice husk. However, after the pistachio nut shell was activated at 1000 °C under an argon atmosphere, the platinum uptake (%) increased two-fold. The pistachio nut shell (original and activated) and rice husk were shown to be better than commercially available activated carbon in terms of adsorption capacity. These two sorbents have also been characterized by FTIR and SEM. Adsorption equilibrium data best complied with the Langmuir isotherm model. Maximum adsorption capacities, Qmax, at 25 °C were found to be 38.31 and 42.02 mg.g - 1for the activated pistachio nut shell and rice husk, respectively. Thermodynamic calculations using the measured ∆H°, ∆S° and ∆G° values indicate that the uptake process was spontaneous and endothermic. The experimental data were shown to be fit the pseudo-second-order kinetic model.

Determination of the Optimum NiS Fire Assay Parameters for Pt, Pd, and Rh in Automotive Exhaust Catalytic Converters

This work investigates the performance of the nickel sulfide fire assay (NiS-FA) for the pyrometallurgical analysis of platinum group elements (PGEs) from mixtures of automotive exhaust catalytic converters (e.g., gasoline, diesel, and diesel particular filter) by assessing the effects of various flux materials and reaction parameters on platinum, palladium, and rhodium recovery. Inductively coupled plasma mass spectrometry and atomic absorption spectroscopy (AAS) are used for the analysis of the NiS-FA beads. We found that the optimum recovery (at least 99.0%) was achieved with reaction of 11.5 g of flux (0.53 w/w ratio, sodium tetraborate:sodium carbonate), 1 g nickel, and 0.84 g sulfur (1.2 w/w ratio, Ni:S) per gram of sample for 90 min at 975°C. Reference standards (NIST SRM 2557) were used to compare efficiencies and identify the optimum conditions. The results are consistent with certified values and PGEs could be recovered within the 95% confidence level. The precision (<4.0% RSD) of all measurements, expressed as percentage relative standard deviation (SD), ranged up to 3.0%.

Studies of Gold Adsorption from Chloride Media

In this paper, adsorption of gold from chloride media using commercial sorbent (Lewatit TP 214 (L-214)) and biomass residue (rice hull (RH)) were investigated. The different adsorption parameters, sorbent dosage, contact time, temperature and pH of solution on adsorption (%) were studied in detail on a batch sorption. Before the RH was activated, adsorption (%) was poor compared with L-214. However, after the RH was activated at 1000 °C under an argon atmosphere, the gold adsorption (%) increased four-fold. X-ray fluorescence (XRF) was used to explore the feasibility this material as an adsorbent for the removal of gold from aqueous solutions. The adsorption equilibrium data were best fitted with the Langmuir isotherm model. The maximum adsorption capacities, Qmax, at 25 °C were found to be 93.46 and 108.70 mg/g for the activated rice hull (ARH) and L-214, respectively. Thermodynamic calculations using ΔH°, ΔS°, ΔG° and Ea values indicate that the adsorption process was spontaneous and endothermic.

SORPTION OF GOLD FROM ELECTRONIC WASTE SOLUTIONS BY A COMMERCIAL SORBENT

In this work, sorption of gold from electronic waste solutions using a commercial sorbent, Lewatit TP 214, was investigated. The effects of the different parameters on gold sorption (%) were studied in detail. Sorbent dosage, contact time, temperature, and solution pH were selected as sorption parameters. Additionally, the gold sorption by Lewatit TP 214 is a diffusion-controlled process with activation energies of 12.28 kJ/mol. The thermodynamic values such as ΔG°, ΔH°, and ΔS° were calculated by experimentally obtained results. The reaction was spontaneous and endothermic. The gold sorption capacity for the sorbent was 100.1 mg gold per gram. XRD patterns revealed that the gold was in its metallic form. The results indicated that Lewatit TP 214 can be effectively used for the sorption of gold from waste solution.

Rhodium cementation from spent plating solution using Taguchi’s method

Abstract The Taguchi method was used as the experimental design to determine the optimum conditions of cementation behaviour of the spent rhodium sulphate plating solution. Cementation was carried out using metallic zinc powder. The experimental conditions were studied in the range of 25–45°C for reaction temperature (A), 0·5–1·5 for pH of solution (B), 30–50 mg for zinc powder (C) and 30–60 min for reaction time (D). Experimental parameters and their levels were determined in the light of preliminary tests. An orthogonal array (OA) L934 consisting of four parameters each with three levels, was chosen. The optimal conditions found for cementation of rhodium, such as: reaction temperature, pH of the solution, mass of zinc and reaction time are respectively: 45°C, 1·5, 50 mg and 60 min. A verification experiment was conducted under optimum conditions and it was found that theoretically calculated and experimentally obtained results were in good agreement at 99·98 and 99·95% respectively. On a utilisé la méthode de Taguchi comme plan expérimental dans la détermination des conditions optimales du comportement de cémentation de la solution usée de sulfate de rhodium pour galvanoplastie. On a effectué la cémentation en utilisant de la poudre métallique de zinc. On a étudié les conditions expérimentales dans la gamme de 25 à 45°C pour la température de la réaction (A), 0·5 à 1·5 pour le pH de la solution (B), 30 à 50 mg pour la poudre de zinc (C) et 30 à 60 min pour la durée de réaction (D). On a déterminé les paramètres expérimentaux et leurs niveaux au moyen d’essais préliminaires. On a choisi un arrangement orthogonal (OA) L9(34) comprenant quatre paramètres, chacun à trois niveaux. Les conditions optimales de la cémentation du rhodium, incluant la température de réaction, le pH de la solution, la masse du zinc et la durée de réaction étaient respectivement de 45°C, 1·5, 50 mg et 60 min. On a effectué une expérience de vérification sous les conditions optimales et l’on a trouvé que les résultats calculés théoriquement et les résultats obtenus expérimentalement étaient en bon accord, avec 99·98 et 99·95% respectivement

Reductive atmospheric acid leaching of spent alkaline batteries in H2SO4/Na2SO3 solutions

This work studies the optimum reductive leaching process for manganese and zinc recovery from spent alkaline battery paste. The effects of reducing agents, acid concentration, pulp density, reaction temperature, and leaching time on the dissolution of manganese and zinc were investigated in detail. Manganese dissolution by reductive acidic media is an intermediate-controlled process with an activation energy of 12.28 kJ·mol−1. After being leached, manganese and zinc were selectively precipitated with sodium hydroxide. The zinc was entirely converted into zincate (Zn(OH)42−) ions and thus did not co-precipitate with manganese hydroxide during this treatment (2.0 M NaOH, 90 min, 200 r/min, pH > 13). After the manganese was removed from the solution, the Zn(OH)42− was precipitated as zinc sulfate in the presence of sulfuric acid. The results indicated that this process could be effective in recovering manganese and zinc from alkaline batteries.

Fabrication and Characterization of Antibacterial Polyurethane Acrylate-based Materials

In this paper, the fabrication of the photocured materials which contained silver nanoparticles (Ag-NPs) was studied on the properties of materials such as physical, mechanical and thermal properties, especially antibacterial activity. Therefore, silver nanoparticles were prepared and added into the polyurethane based matrix. Chemical and morphological structures of the photocured materials were characterized by FTIR and SEM analysis. SEM images proved the size of the silver nanoparticles and their dispersion into polymer matrix. Thermal, mechanical and optical properties of photocured materials results showed that the prepared polymer compositions containing Ag-NPs exhibited high modulus and better thermal property. Moreover, the antibacterial properties of the polyurethane based materials and polymer material containing AgNPs were determined and these AgNPs containing photocured materials pointed out good antibacterial activity against Escherichia coli and Staphylococcus aureus.

Determination of the Optimum NiS Fire Assay Parameters FOR Platinum in Catalytic Converters

The nickel sulfide (NiS) fire assay has been used to quantify, platinum (Pt) in catalytic converters. The use of various flux materials and the effects of different parameters such as quantity of flux, flux mixture ratio (i.e. B2O3:Na2O ratio) and temperature were compared on Pt recovery. The fire assay buttons were characterized using different techniques such as Atomic absorption spectrometer (AAS) and inductively coupled plasma mass spectrometry (ICP-MS). We found that the optimum condition to recover Pt was achieved with the use of 57.5 g flux (sodium tetraborate + sodium carbonate), 5 g Ni (as 6.36 g NiO), and 5 g S° per five gram of sample at 900°C. The recovery of Pt after an hour was, 95%. It is proposed that a method to isolate at least 95% of the Pt present in catalytic converters using NiS fire assay.

Recovery of Platinum from Dilute Chloride Media Using Biosorbents

Pistachio nut shells and Rice husk, a biomass residue, were investigated as adsorbents for the platinum uptake from synthetically prepared dilute chloroplatinic acid solutions. The effects of the different uptake parameters on platinum uptake (%) were studied in detail on a batch sorption. Before the pistachio nut shell material was activated, platinum uptake (%) was poor compared with rice husk. However, after the pistachio nut shell material was activated at 1000°C under an argon atmosphere, the platinum uptake (%) increased two-fold. The pistachio nut shell (inactivated and activated) and rice husk were characterized by Attenuated Total Reflection-Fourier transform infrared spectroscopy (ATR-FTIR).