Precipitation to remove calcium ions from stabilized human urine as a pre-treatment for reverse osmosis

Concentration of Ca(OH)2 stabilized urine by reverse osmosis (RO) has the potential to cause CaCO3 scaling on the membranes. The aim of this research was to determine whether the addition of carbonate salts could be used to precipitate CaCO3 prior to RO concentration and how to accurately dose the salts. Dosing of NaHCO3 or Na2CO3 reduced the calcium concentration to <0.18 mmol L−1, whilst maintaining a pH > 11. This is the pH threshold for enzymatic urea hydrolysis in urine, but above the operating pH range of most membranes. However, the pH could be decreased by adding an acid. Measuring conductivity as a proxy for the calcium concentration was found to be an effective method to determine the dose of salt required. Simulations with other carbonate producing salts (KHCO3, Mg­CO3, and NH4HCO3) were also shown to be effective. However, NH4HCO3 ($0.53 m−3 urine) was the only other salt comparable in cost to NaHCO3 ($0.49 m−3 urine) and resulted in a final pH within the normal operating range of membranes. The addition of NH4HCO3 would add extra N to the urine rather than sodium ions when dosing NaHCO3. The choice of salt will ultimately depend on what liquid fertilizer composition is desired.

Increasing the production of gas condensate by using ammonium carbonate salts

The work is devoted to the problem of increasing gas condensate production in gas condensate fields. It was found that ammonium carbonate salts, in the absence of calcium chloride type waters, interact with carbonate rocks, increase the permeability of reservoirs. Solutions of ammonium carbonate salts when interacting with formation water of the calcium chloride type form chemically precipitated chalk in the pore space, while the permeability of carbonate rocks decreases. A set of experimental studies was carried out to study the displacing and washing properties of ammonium carbonate salts. It was found that ammonium carbonate salts have high displacing properties, the displacement ratio of kerosene by NH4HCO3 solution is 0.75-0.80, while reservoir water – 0.55-0.58. According to the results of laboratory studies of the displacing and washing characteristics of ammonium carbonate salts, conclusions were made about the effect of bicarbonate solution (ammonium carbonate salts) on the production characteristics of a well in reservoir conditions at temperatures of 80-100 °C and above. Industrial tests of ammonium carbonate salts showed an increase in gas flow by 30-50% at wells № 23 of Opishnia, № 115 of Mashivka, № 3 of Tymofiivka gas condensate fields. The effect of formation treatment with ammonium carbonate salts is achieved due to clearing of well bottom zone and increasing the formation permeability. At wells № 56, 108 of Yablunivka and № 58 of Tymofiivka gas condensate fields, an increase in the condensate ratio was observed by 22-35%. The effectiveness of this treatment is associated with the simultaneous bottomhole zone cleaning from asphalt-resinous contaminants and permeability increase, as well as with the hydrophilization of the pore space and mobility increase of condensate precipitated as a result of carbon dioxide effect, which was rejected as a result of decomposition of ammonium carbonate. Thus, experimental and industrial tests in Opishnia, Mashivka, Tymofiivka, Yablunivka gas condensate fields of Poltava region confirmed the effectiveness of using ammonium carbonate to increase hydrocarbon production. The prospect of further research is aimed at developing a technology for increasing the production of liquid hydrocarbons by using ammonium carbonate salts.

B(C6F5)3-catalyzed three-component tandem reaction to construct novel polycyclic quinone derivatives: synthesis of a carbonate salts chromogenic chemosensor

We have realized B(C6F5)3-catalyzed three-components tandem reaction of naphthoquinone, indole and maleimide, which has broad adaptability of substrate and good compatibility of functional group, and synthesized 33 examples. After photophysical...

Mapping groundwater hardness in wells as a source of drinking water for the people

Herce Farida Solossa 20.2018.2.00117 Mapping of Groundwater Hardness Distribution of Drinking Water for Bangkalan District Community, in 2019. Thesis, Department of Environmental Engineering, Faculty of Civil Engineering and Planning, Adhi Tama Institute of Technology Surabaya, Advisor Dr. Yulfiah, ST., Msi. Water hardness is the content of certain minerals in water, generally calcium (Ca) and magnesium (Mg) ions in the form of carbonate salts and this content if it exceeds quality standards can have an impact on human health. The purpose of this study is to map the distribution of groundwater hardness as a source of water supply in Kab. Bangkalan. The sample of this study is shallow wells with a depth not exceeding 20 m. This type of research is a descriptive study with a qualitative and quantitative approach. The research sample was taken as many as 18 following the number of subdistricts in Kab. Base Samples taken are water source wells used by the community. Sampling time is the dry season. Samples taken are stored in bottles and immediately taken to the laboratory for examination. Sampling locations are made in the form of maps with the ArcGis application. The conclusion of this research is that the level of hardness in groundwater in Kab. Base has moderate value - maximum. The distribution of hard water is also evenly distributed throughout the Kab. Base with the maximum distribution from east-west to east and east-east while the hardening is starting from north and northeast to south, southwest and west. This suggestion that can be made is that residents who use shallow wells should use a filter and cook it first for drinking needs. Keywords: Mapping, hard groundwater, drinking water sourcesKeywords: Mapping, hard groundwater, drinking water sources.

Experimental and Computational Evaluation of Heavy Metal Cation Adsorption for Molecular Design of Hydrothermal Char

A model hydrochar was synthesized from glucose at 180 °C and its Cu(II) sorption capacity was studied experimentally and computationally as an example of molecular-level adsorbent design. The sorption capacity of the glucose hydrochar was less than detection limits (3 mg g−1) and increased significantly with simple alkali treatments with hydroxide and carbonate salts of K and Na. Sorption capacity depended on the salt used for alkali treatment, with hydroxides leading to greater improvement than carbonates and K+ more than Na+. Subsequent zeta potential and infrared spectroscopy analysis implicated the importance of electrostatic interactions in Cu(II) sorption to the hydrochar surface. Computational modeling using Density Functional Theory (DFT) rationalized the binding as electrostatic interactions with carboxylate groups; similarly, DFT calculations were consistent with the finding that K+ was more effective than Na+ at activating the hydrochar. Based on this finding, custom-synthesized hydrochars were synthesized from glucose-acrylic acid and glucose-vinyl sulfonic acid precursors, with subsequent improvements in Cu(II) adsorption capacity. The performance of these hydrochars was compared with ion exchange resins, with the finding that Cu(II)-binding site stoichiometry is superior in the hydrochars compared with the resins, offering potential for future improvements in hydrochar design.

CO2 Derivatives of Molecular Tin Compounds. Part 1: Hemicarbonato and Carbonato Complexes

This review focuses on organotin compounds bearing hemicarbonate and carbonate ligands, and whose molecular structures have been previously resolved by single-crystal X-ray diffraction analysis. Most of them were isolated within the framework of studies devoted to the reactivity of tin precursors with carbon dioxide at atmospheric or elevated pressure. Alternatively, and essentially for the preparation of some carbonato derivatives, inorganic carbonate salts such as K2CO3, Cs2CO3, Na2CO3 and NaHCO3 were also used as coreagents. In terms of the number of X-ray structures, carbonate compounds are the most widely represented (to date, there are 23 depositions in the Cambridge Structural Database), while hemicarbonate derivatives are rarer; only three have so far been characterized in the solid-state, and exclusively for diorganotin complexes. For each compound, the synthesis conditions are first specified. Structural aspects involving, in particular, the modes of coordination of the hemicarbonato and carbonato moieties and the coordination geometry around tin are then described and illustrated (for most cases) by showing molecular representations. Moreover, when they were available in the original reports, some characteristic spectroscopic data are also given for comparison (in table form). Carbonato complexes are arbitrarily listed according to their decreasing number of hydrocarbon substituents linked to tin atoms, namely tri-, di-, and mono-organotins. Four additional examples, involving three CO2 derivatives of C,N-chelated stannoxanes and one of a trinuclear nickel cluster Sn-capped, are also included in the last part of the chapter.

Dialing in Direct Air Capture of CO2 by Crystal Engineering of Bis-iminoguanidines

We report a structure-properties relationship study of DAC by crystallization of bis-iminoguanidine (BIG) carbonate salts. The study focuses on a series of basic BIG structures including the glyoxal-bis(iminoguanidine) prototype (GBIG) and its simple analogs methylglyoxal-bis(iminoguanidine) (MGBIG) and diacetyl-bis(iminoguanidine) (DABIG). We find that minor structural modifications in the molecular structure of GBIG, such as substituting one or two hydrogen atoms with methyl groups, result in major changes in the crystal structures, induced by the increased conformational flexibility and steric hindrance. As a result, the corresponding aqueous solubilities within the series increase significantly, leading in turn to enhanced DAC performances.