Processing of formate solutions obtained from red mud leaching

The paper determines the indicators of the developed process flow for the complex processing of red sludge via the formate method: recovery of components; yield and composition of products when processing a sample of formate solution obtained from red mud leaching. The conducted experiments used red mud generated in the production of alumina at the Urals Aluminium Smelter. The samples of formate solution obtained in the course of red mud leaching were analyzed using an Optima 8000 ICP-OES Spectrometer, a Sartorius MA-30 Moisture Analyzer to measure moisture content, as well as an ARL 9800 XRF Spectrometer to ascertain the mass fraction of elements in metal and nonmetal specimens found in one of three states (solid, liquid, or powder). These experiments were performed while continuously measuring and monitoring pH values by means of a pH meter having a thermal compensation function. The performed experiments involved the total recovery of valuable elements from formate solutions produced during red mud leaching. A concentrate containing Al, Sc, and rare earth elements (REEs) was processed to produce scandium oxide and rare earth metal concentrate (after dissolving aluminum in an alkali). Rare earth metals and scandium were shown to concentrate in the solid phase; scandium was then selectively leached with a sodium bicarbonate solution to form water-soluble carbonate complexes [Sc(CO3)4]5- having carbonate ions СО32- and НСО3-. When using the proposed technology, the overall recovery of scandium and REEs amounts to 98–99%, whereas that of aluminum, calcium formate, and sodium formate from the produced solution reaches 99%. The processing of formate solution yields the following end products: scandium oxide (99 wt% Sc2O3) and REE concentrate (content of 56.1%). The paper demonstrates the possibility in pri nciple to process solutions obtained from the flow-through leaching of red mud via the formate method.

Fabrication of a state of the art mesh lock polymer for water based solid free drilling fluid

Polymers are used widely in various kinds of drilling fluid to maintain the proper rheological properties. However, most of them are not available for high-temperature or salt solutions due to poor temperature and salt resistance. To ameliorate the temperature and salt resistance of polymer used in the solid-free water-based drilling fluid, a novel polymer with a kind of "Mesh-Lock" reinforced network cross structure, named PLY-F [main monomer acrylic acid (AA), acrylamide (AM), functional monomers 2-acrylamide-2-methylpropanesulfonic acid (AMPS) N-vinylpyrrolidone (NVP) and C16DMAAC] were prepared through free radical polymerization of an aqueous solution of organic cross-linking agent pentaerythritol triallyl ether (PTE) as a cross-linking system, Potassium persulfate (KPS) and sodium bisulfite as the initiator for the first time. The surface morphology, crosslinking architecture and temperature and salt resistance of the PLY-F were fully characterized with several means including SEM, FT-IR, 13CNMR, dynamic rheology, and long-term thermal stability. The SEM observation indicated that the PLY-F exhibits a regular “Mesh-Lock” reinforced network cross structure. FT-IR, 13CNMR analysis indicated that the characteristic functional groups of each monomer such as AM, AA, AMPS and NVP were all together in the polymer. The results show that the apparent viscosity retention rate of the PLY-F in the potassium formate solution (with a density of 1.3 g/cm3) was more than 80% after heat rolling for 72 h at 200 °C and the plastic viscosity retention rate reached 90.3%. Moreover, the salt resistance of the polymer can reach the density of 1.4 g/cm3 (potassium formate solution) under 200 °C and the temperature resistance can reach 220 °C under the density of 1.3 g/cm3 (potassium formate solution). Besides, the PLY-F still has good rheological properties in other saturated solutions (NaCl, HCOONa) under 210 °C.

Glycine for Enhanced Water Imbibition in Carbonate Reservoirs – What is the Role of Amino Group?

Previous studies indicated the efficacy of the simplest amino acid, glycine, as an aqueous additive for enhanced water imbibition in carbonate reservoirs. The objective of this research was to investigate the importance of the amino group of glycine in its enhanced water imbibition. To this end, glycine was compared with two carboxylates (acetate and formate) with/without adding hydrogen chloride (HCl) for adjusting the solution pH. Note that the amino group is the only difference between glycine and acetate. Contact-angle experiments on calcite were carried out at 347 K and atmospheric pressure with 68000-ppm reservoir brine (RB), and 4 different concentrations of glycine, acetate, and formate solutions in RB. To test the hypothesis that calcite dissolution is one of the main mechanisms in wettability alteration by glycine, we performed another set of contact angle experiments by adding HCl to brine, acetate, and formate solutions. HCl was added to match the pH of the glycine solution at the same concentration. We also performed imbibition tests with Texas Cream Limestone cores at 347 K with brine, glycine, acetate, and formate solutions (with and without HCl) in RB at 5.0 wt%. Contact-angle results indicated that glycine changed calcite's wettability from oil-wet to water-wet (45°). However, acetate solution was not able to change the wettability to water-wet; and formate moderately decreased the contact angle to 80°. The pH level increased from 6.1 to 7.6 after the contact angle experiment in glycine solution, indicating the consumption of hydrogen ions due to calcite dissolution. The levels of pH in formate and acetate solutions, however, decreased from 8.4 to 7.8. The acidity of glycine above its isoelectric point arises from the deprotonation of the carboxyl group. Imbibition tests with carbonate cores supported the observations from the contact-angle experiments. The oil recovery was 31% for glycine solution, 20% for RB, 21% for formate solution, and 19% for acetate solution. This re-confirmed the effectiveness of glycine as an additive to improve the oil recovery from carbonates. An additional set of imbibition tests revealed that acetate at the pH reduced to the same level as glycine was still not able to recover as much oil as glycine. This showed that glycine recovered oil not only because of the calcite dissolution and the carboxyl group, but also because of the amino group. It is hypothesized that the amino group with its electron donor ability creates a chelation effect that makes glycine entropically more favorable to get attached to the calcite surface than acetate. Another important result is that the formate solution at an adjusted pH resulted in a greater oil recovery than RB or RB at the same pH. This indicates that there is an optimal pH for the carboxyl group to be effective in wettability alteration as also indicated by the pH change during the contact-angle experiment.

Probe metal binding mode of imine covalent organic frameworks: cycloiridation for (photo)catalytic hydrogen evolution from formate

This study describes cyclometallation as a new metal binding mode for imine-based COFs. The iridacycle decorated COF could be used for catalytic hydrogen evolution from aqueous formate solution with high stability and high efficacy.

Abundance and distribution of microplastics in water and sediments of the river Elbe, Germany

<p>Plastic pollution in the aquatic environment has gained worldwide attention in the last years. Microplastics have been investigated for over 45 years especially in the marine environment, but only in the past years research has also started to focus on freshwater environments. In the frame of the project about macro- and microplastics in German rivers, samples from 11 sites from the German part of the river Elbe were taken in order to study the plastic pollution in water and sediment, detect sinks of microplastics and better understand transport mechanisms.</p><p>The sediment samples were taken with a Van-Veen-grabber, the water samples from the Elbe with an Apstein plankton net (mesh size 150 µm) from the same location. The sediment samples were presorted with wet sieving, organic digestion and density separation and filtered on aluminium oxide filters. For the water samples, the organic matter was digested using a reagent composed of equal volumes of 10 M KOH and 30 % H2O2, then, the microplastic particles were isolated from remaining matrix by density floatation using 1.6 g/mL potassium formate solution and pressure filtration. Analysis was done by visual inspection, selected particles measured with Fourier-transform infrared spectroscopy and masses calculated with a pyrolysis GC-MS.</p><p>The results of the sediments of the Elbe reveal that tentative microplastic concentrations differed intensively between the different river compartments. Microplastics in the sediments were in average 600,000-fold higher than in the water samples (when referring to the same volume). The amount of particles also varies significantly between the sampling sites. In sediment samples, microplastic concentrations decreased downstream, in water samples, concentrations varied stronger. The form of the particles is also site specific. In two samples, more than 80% spheres were counted whereas the 6 locations downstream reveal an increase in fragments. Polymer distribution differed between the water and sediment phase with mostly PE and PP in the water samples and a more diverse distribution in the sediments.</p>