Use of the O2-Thiosemicarbazide System, for the Leaching of: Gold and Copper from WEEE & Silver Contained in Mining Wastes

Environmental pollution today is a latent risk for humanity, here the need to recycle waste of all kinds. This work is related to the kinetic study of the leaching of gold and copper contained in waste electrical and electronic equipment (WEEE) and silver contained in mining wastes (MW), using the O2-thiosemicarbazide system. The results obtained show that this non-toxic leaching system is adequate for the leaching of said metals. Reaction orders were found ranging from 0 (Cu), 0.93 (Ag), and 2.01 (Au) for the effect of the reagent concentration and maximum recoveries of 77.7% (Cu), 95.8% (Au), and 60% (Ag) were obtained. Likewise, the activation energies found show that the leaching of WEEE is controlled by diffusion (Cu Ea = 9.06 and Au Ea = 18.25 kJ/Kmol), while the leaching of MW (Ea = 45.55 kJ/Kmol) is controlled by the chemical reaction. For the case of stirring rate, it was found a low effect and only particles from WEEE and MW must be suspended in solution to proceed with the leaching. The pH has effect only at values above 8, and finally, for the case of MW, the O2 partial pressure has a market effect, going the Ag leaching from 33% at 0.2 atm up to 60% at a 1 atm.

Recovery of Coal Values from Middling and Rejects by Froth Flotation and Mozley Mineral Separation

The recovery of coals values from Middling and Rejects carries out by using Froth flotation and Mozley Mineral Separation. The middling and rejects are the waste products from gravity beneficiation process, it has been noted that most of washery plants are selling this product at low cost because they have less values.The independent variables selected for Mozley Mineral Separator and their ranges were indicated in the parentheses as follow, water flow rates (400, 600, 800ml/s), amplitude (1.25, 1.5, 1.75inch) and collection time (30, 40, 60 s) while the independent variables for froth flotation were; Pulp density (10, 12.5, 15 %), collector dosage (39.3, 44.4, 49.5 g/t) and frother dosage (61.8, 65.3, 68.8 g/t). The number of experimental runs and regression equation determined by using Design Expert softwareThe d80 for middling and rejects samples were 10.5mm and 12.89mm respectively. The ash contents for the middling sample treated by froth flotation decrease from 37% to 15.85% at the reagent concentration of 49.5g/t collector, 65.3g/t frother and pulp density of 10%. The froth flotation results of middling sample shown to have a great reduction of ash contents. The overall optimum middling recovery and yield for washery grade I and II attain at reagent concentration and pulp density of 47.703g/t, 68.568g/t and 13.2% for collector, frother and pulp density respectively. The feed of reject coal was 71% and the ash contents reduced to 28.87% with the recovery of 0.85%. The analysis through Mozley mineral separator did not show significant changes in the reduction of ash from both middling and rejects. The ash contents achieved were above the scope of the studies for recovering of coal values. The experiments for middling and reject by froth flotation and Mozley mineral separator may be carried out by varying other parameters as well as the type of methods.

Use Of Experience Gained In The Process Of Teaching Chemistry

This article describes improved experiments on factors influencing the rate of chemical reaction from general chemistry in continuous learning: catalyst and temperature, reagent surface area, dependence on reagent concentration.

A bridging immunogenicity assay for anti-cabiralizumab antibodies: overcoming the low assay cut point and drug tolerance challenges

Background: To support the clinical studies of cabiralizumab, an immunogenicity assay for detecting anti-cabiralizumab antibodies is required. Results: Strategies were developed to overcome two major bioanalytical challenges: poor drug tolerance of the anti-drug antibodies assay and very low cut point observed in the screening and confirmatory assays. By using acid dissociation (400 mM glycine solution at pH 2.0), drug tolerance of 200 μg/ml drug was achieved for both the screening and confirmatory assays. Effects of biological matrix (disease state vs normal serum) and assay conditions (capture/detector reagent concentration, minimum required dilution, acid pretreatment) on assay cut points were systematically evaluated. Conclusion: A bridging immunogenicity assay for detecting anti-cabiralizumab antibodies in human serum has been successfully developed, validated and applied to clinical studies.

Analyzing a denitration process in the context of underground well uranium leaching

Purpose is to increase a sorbent denitration degree in the context of underground uranium leaching while optimizing reagent concentration as well as a degree of the solution activation on the basis of laboratory research. Methods. Analysis has been applied as well as scientific generalization of scientific-and-engineering information, laboratory research, statistic processing, and analysis of the research results. The laboratory experiments involved specific mixture to obtain comparative data of sulfuric solution activity and identify optimum degree of the solution activation for denitration. After processing, the solution from activator was analyzed as for its activity; the bulk was poured into a tank for repetitive experiments. First, the research did not involve the solution activation; then, activation with 4-15 minutes was added. Sulfuric acid concentration was 20 and 25 g/dm3; L-S ratio was 1/8; and washing time was 40, 60, and 120 minutes. Findings. Laboratory research results have been demonstrated concerning sorbent denitration in terms of varying degrees of activation, sulfuric acid concentration, and response time. It has been demonstrated that it is sufficient for washing solution activation to activate reagent only before extra intensification of a mother solution resulting in the reduced volume of the solution being processed and costs. It has been determined that five- to nine-minute activation period is the efficient interval factoring into the decreased nitrate content in the sorbent after washing to compare with 9-18% in terms of a basic technique depending upon a reagent concentration. Originality.New dependences of a sorbent denitration degree as well as nitrate content within a solution upon sulfuric acid concentration and the solution activation degree have been defined. Practical implications. Washing solution activation results in the increased denitration degree of a sorbent to compare with the basic technique. The proposed method is more preferable owing to low capital costs. Moreover, it is integrated easily in the available system being also absolutely sustainable. Keywords: denitration, sorbent, sorption, desorption, activation, sulfuric acid, uranium

Application of the Gyrolab microfluidic platform to measure picomolar affinity of a PD-L1-binding Adnectin™ radioligand for positron emission tomography

Advances in in vitro display and protein engineering yield therapeutics with affinities in the picomolar range. The Gyrolab® microfluidics platform uses the kinetic exclusion assay principle to measure subnanomolar solution affinities. This work describes application of the Gyrolab solution affinity module and the new multi-curve analysis feature to determine affinity of the PD-L1 Adnectin™ positron emission tomography radioligand, which was measured as 20 pM for human PD-L1. We also report key parameters that affect assay signal-to-background ratio and data quality, such as detection reagent concentration. Gyrolab offers the necessary throughput for rapid assay development with low sample consumption, as demonstrated in this study, which also provides helpful tips for assay optimization for solution affinity measurement.

Optimization of α-Hydroxyketone and Pyrazine Syntheses Employing Preliminary Reactions of Glucose and Buffer Solutions

SummaryGlucose and selected phosphate buffers have been reacted employing systematic variations in reaction temperature and time (150–160 °C for 60–90 min) to optimize the yield of acetol. This mixture was reacted further with NH4OH, systematically varying reaction conditions and reagent ratios to optimize pyrazine yield. The highest yield of pyrazine was obtained when 1 g of glucose was reacted with 25 mL of buffer at 150–160 °C for 60 min, which in turn was reacted with 1 mL of concentrated aqueous NH4OH at 120–130 °C for 17–18 h. Higher temperatures and higher concentrations of glucose caused a decrease in the yield of pyrazines. The addition of hydrolyzed tobacco-derived F1 protein as a secondary source of nitrogen increased the yield of pyrazines by 2–10% depending on F1 protein concentration. Furthermore, the addition of any α-hydroxyketone, similar in structure to acetol, as a pure reagent to the reaction mixture not only increased the yields of pyrazine by ranging from 25–100 % depending on the reagent concentration, but also significantly altered the qualitative and quantitative distribution of the pyrazines. With all of the reaction parameters examined (reaction time, temperature, reagent ratios, etc.) the most significant impacts on both pyrazine yield and distribution were noted when: 1) glucose was pre-reacted with buffer, 2) hydrolyzed F1 protein was added as a second nitrogen source, and 3) when pure α-hydroxyketones were employed as co-reagents. Use of these reaction parameters was found to dramatically shift the pyrazine distribution toward higher molecular weight resulting in a pyrazine array having more desirable physical and sensory attributes.