Novel Application of Pourbaix Diagrams to Model Precipitation in Upstream Biomanufacturing Process Solutions

Commercial production of therapeutic proteins using mammalian cells requires complex process solutions, and consistency of these process solutions is critical to maintaining product titer and quality between batches. Inconsistencies between process solutions prepared at bench and commercial scale may be due to differences in mixing time, temperature, and pH which can lead to precipitation and subsequent removal via filtration of critical solution components such as trace metals. Pourbaix diagrams provide a useful tool to model the solubility of trace metals and were applied to troubleshoot the scale-up of nutrient feed preparation after inconsistencies in product titer were observed between bench- and manufacturing-scale batches. Pourbaix diagrams modeled the solubility of key metals in solution at various stages of the nutrient feed preparation and identified copper precipitation as the likely root cause of inconsistent media stability at commercial scale. Copper precipitation increased proportionally with temperature in bench-scale preparations of nutrient feed and temperature was identified as the root cause of copper precipitation at the commercial scale. Additionally, cell culture copper titration studies performed in bench-scale bioreactors linked copper-deficient mammalian cell culture to inconsistent titers at the commercial scale. Pourbaix diagrams can predict when trace metals are at risk of precipitating and can be used to mitigate risk during the scale-up of complex media preparations.

Effects of Silicon, Chromium, and Copper on Kinetic Parameters of Precipitation during Tempering of Medium Carbon Steels

Understanding the tempering behavior of medium carbon steels is mandatory if their mechanical properties are to be improved. For an optimal technology to be developed for this purpose, a substantial experimental basis is needed to extract quantitative information on the microstructure of the tempered material. This paper reports on the characterization of microstructural changes induced by tempering in medium-carbon steels alloyed with Si, Cr, Cu, and Mn using state-of-the-art experimental techniques. Complementarities among these techniques are highlighted. The evolution of transition carbides, cementite, and copper precipitates is described using data from X-ray diffraction, small and ultra-small angle neutron diffraction, transmission electron microscopy, and dilatometry observation. The effects of silicon, chromium, and copper on the mechanism of carbide and copper precipitation are discussed. The considerable changes found in the size and volume of copper precipitates correlate well with the difference in the yield stress between tempered steels with and without copper.

Fluid inclusions, H-O-S isotopic characteristics and genesis of the Chambishi copper deposit, Zambia

In this paper, fluid inclusions and H-O-S isotope geochemistry of the Chambishi copper deposit in Zambia are studied. According to the fluid inclusion in quartz and H-O-S isotope characteristics, it is concluded that ore-forming hydrothermal fluid is derived from mantle source and crust source magma mingling, the cause of copper precipitation, sedimentary type sulfur layered mineralization are mainly from diagenetic sulfides and seawater sulfate. Sulfate is mainly reduced by thermochemical method. The hydrothermal vein mineralization of Chambishi copper deposit is closely related to the magmatic activity in the middle Neoproterozoic, and the sedimentary stratified mineralization is mainly related to the large-scale orogeny and regional metamorphism in the late Neoproterozoic.

Study on recovery of copper and zinc from cyanide lean solution in a smelting company

In the process of cyanidation of gold concentrate from a smelting company, the content of copper and zinc in the liquid gradually increased. In production, acidizing process is used to treat the lean solution from high copper concentrate, and mixed products containing copper, zinc and other metals are produced. In this paper, the pH value of zinc precipitation is 6.0 and the pH value of copper precipitation is 3.0 through theoretical calculation and experiment. The separation of copper and zinc in the lean solution is realized successfully. The zinc product with grade of 42.97% and the copper product with grade of 58.33% are produced.

Copper Precipitation Behavior during Continuous Cooling and Subsequent Aging of Powder-Forged Fe-2.5Cu-C Alloy

Microstructure and property evolution of a powder-forged Fe-2.5Cu-C alloy during continuous cooling and subsequent aging were investigated to improve its mechanical properties. During continuous cooling, copper precipitates formed were consistent with the interphase mechanism when the cooling rate was less than 7 °C/s; however, the hardness of the specimen was always higher at faster cooling rates because finer grains and harder phases formed. During subsequent aging, copper precipitates formed and/or coarsened continuously while the hardness of the alloys was greatly influenced by the combined effects of the primary and secondary precipitates, as revealed by the theoretical calculations. In addition, the forming and evolving mechanisms of the copper precipitates at different stages were also discussed based on the experimental results. This study will provide guidance to the industry for achieving high performance in the powder-forged products by treatment manipulation.

Quaternization of Composite Algal/PEI Beads for Enhanced Uranium Sorption—Application to Ore Acidic Leachate

The necessity to recover uranium from dilute solutions (for environmental/safety and resource management) is driving research towards developing new sorbents. This study focuses on the enhancement of U(VI) sorption properties of composite algal/Polyethylenimine beads through the quaternization of the support (by reaction with glycidyltrimethylammonium chloride). The sorbent is fully characterized by FTIR, XPS for confirming the contribution of protonated amine and quaternary ammonium groups on U(VI) binding (with possible contribution of hydroxyl and carboxyl groups, depending on the pH). The sorption properties are investigated in batch with reference to pH effect (optimum value: pH 4), uptake kinetics (equilibrium: 40 min) and sorption isotherms (maximum sorption capacity: 0.86 mmol U g−1). Metal desorption (with 0.5 M NaCl/0.5 M HCl) is highly efficient and the sorbent can be reused for five cycles with limited decrease in performance. The sorbent is successfully applied to the selective recovery of U(VI) from acidic leachate of uranium ore, after pre-treatment (cementation of copper, precipitation of rare earth elements with oxalate, and precipitation of iron). A pure yellow cake is obtained after precipitation of the eluate.

A Novel Design to Enhance the Mechanical Properties in Cu-Bearing Antibacterial Stainless Steel

A novel method based on nano-scale precipitation hardening has been studied to strengthen copper-bearing ferrite antibacterial stainless steel. Bimodal precipitations can be observed after antibacterial annealing and low temperature aging treatment, which are large rod-shaped precipitates and nano-sized spherical precipitates, respectively. Due to two different morphological precipitates, the strength of the material is significantly improved without sacrificing formability, and at the same time, the excellent antibacterial properties remain. Under low temperature aging treatment, there is no obvious evidence to show the segregation at the interface between the rod-shaped copper precipitation and the matrix due to the low segregation coefficient of copper. The nano-sized copper precipitation uniformly nucleated and distributed on the matrix. The optimized heat treatment process is antibacterial annealing at 800 °C for half an hour followed by one-hour-aging treatment at 550 °C.