Removal Of Cl Research Articles

Partitioning of volatile components (Cl, F, CO2) in water-saturated fluid-magmatic systems of various composition

The results of experimental studies of the behavior of volatile components (Cl, F, CO2 and H2O) in fluid-magmatic systems are presented. The maximum chlorine content in magmatic melts mainly depends on the composition of the melt and, to a lesser extent, on pressure (10300 MPa) and temperature (8001000C). The Cl content in the melt increases from 0.20.3 to 35 wt.% with increasing in the Ca content during the transition from polymerized granitoid to depolymerized basaltic melts. The pressure dependence of solubility has a maximum at a pressure of about 100200 MPa. A tendency of increasing in the Cl content and decreasing in the F content in the melt during the transition from acidic and alkaline to basaltic melts has been established. The maximum Cl content in the melt significantly increases from rhyolitic (up to 0.25 wt.%) to phonolitic (up to 0.85 wt.%) and dacitic (up to 1.2 wt.%) at temperatures of 10001200C and pressure of 200 MPa. The addition of CO2 to the system causes an increase in the Cl content in the melt by 2025 relative %, which is apparently associated with an increase in the Cl activity in the fluid. In this case, the H2O content in the melt decreases by ~ 0.51.0 wt.%. A strong effect of hydrolysis was shown in the interaction of an alumina-rich granitic melt with ~ 0.51N chloride fluid. This effect shows that at hypabyssal magmatic conditions (P = 100 MPa, T = 750C), the fluid is acidic (the pH after the experiment is ~ 11.5) and it is characterized by high dissolving power. It was established experimentally that as a result of the interaction of aqueous Na-K-Ca-chloride fluid of variable composition with granodioritic and granitic melts in the pressure range of ~ 100200 MPa and temperatures of 8201000C and with increasing in the total salt content, the Na and K replace Ca in the silicate melt, displacing the latter into the fluid, that is enriched in CaCl2 and is depleted in NaCl. Experimental results on the joint partitioning of Cl and F provide a quantitative basis for understanding the degassing processes in the course of the evolution of alkaline and basaltic magmas. They are important for assessing the extent of the removal of Cl and F into the earths atmosphere during volcanic activity and the effects of this removal on climate change.

Kinetics of chlorine deposition and removal over promoted silver catalysts during ethylene epoxidation

High partial oxidation selectivity in ethylene oxidation over Ag catalysts is achieved in part via the presence of adsorbed chlorine promoters. Chlorine coverage during ethylene oxidation is maintained by co-feeding organic chlorides in ppm levels and alkane moderators in concentrations of ~0.5 mol%. The relative efficacy of organic chlorides in Cl deposition and of alkanes in Cl removal is typically estimated using empirical correlations. Apparent kinetics of Cl removal were measured by feeding ethyl chloride and propane during ethylene oxidation catalysis over a highly-promoted Ag/α-Al2O3 catalyst and quantifying the rate of chloropropane formation during steady state reaction. Propane oxychlorination forms 1- and 2-chloropropane in a ~1:2 ratio, as expected given the lower bond dissociation enthalpy of methylene than methyl CH bonds in propane, and at total rates on the order of 10-4 mol C3H7Cl (mol Agsurf)-1 s−1. Concurrent ethylene oxidation rates of order 10-1 mol (mol Agsurf)-1 s−1 provide evidence that Cl moderation occurs in a distinct catalytic cycle over promoted Ag catalysts. Cl removal has a supralinear dependence on propane pressure (PC3H8) and an inverse dependence on ethyl chloride pressure (PC2H5Cl) at high PC2H5Cl/PC3H8, while Cl removal is positive order in pressures of both C2H5Cl and C3H8 at low PC2H5Cl/PC3H8, as expected for surfaces that are increasingly covered in Cl as PC2H5Cl/PC3H8 increases. Chloropropane formation rates were positive order in dioxygen pressure for all PC2H5Cl/PC3H8 ratios. Taken together, the kinetics of Cl removal require both rate determining deposition of Cl from an alkyl chloride and kinetically relevant removal of Cl by an alkane. We develop a kinetic model that describes these trends and allows for quantification of rate and equilibrium parameters, and provide evidence for the elementary steps enumerated by measuring a kinetic isotope effect and assessing the fate of alkyl fragments from chloroethane and chloropropane in gas-phase batch reactions. Rate and equilibrium constants regressed from this kinetic model are used to develop an isotherm for Cl coverage as a function of the ratio of organic chloride promoter to alkane moderator pressures. This isotherm quantitatively predicts Cl coverages measured in situ after steady state reactions with feedstreams containing both ethyl chloride-ethane and ethyl chloride-propane mixtures. Measured reaction orders for chloropropane formation with respect to ethylene and carbon dioxide pressure reflect surface ethylene and carbon dioxide coverages that are lower for sites that form chloropropane than for sites that form ethylene oxide, suggesting that site ensembles for Cl deposition and removal vary from those involved in selective oxidation of ethylene.

Selective Removal of Cl - and SO 4 2- from Seawater Using Ag- and Pb-exchanged Natural Clinoptilolite Zeolites

Selective Removal of Cl - and SO 4 2- from Seawater Using Ag- and Pb-exchanged Natural Clinoptilolite Zeolites

Removal and recovery of chloride ions in concentrated leachate by Bi(III) containing oxides quantum dots/two-dimensional flakes

The high concentration of chloride (Cl−) ions in leachate often has negative effects in their harmless treatments, and the common treatments containing the ion exchange method consume excessive antichlors due to their large particle sizes and unfavorable morphologies. Herein, the antichlors of the Bi(III) containing oxides with quantum dots (QDs) or two-dimensional (2D) structures are first explored for the removal and recovery of Cl− ions in concentrated leachate. By using the QDs/2D flakes constructed antichlors of Bi2O3 and the magnetite Bi-Ti composite, the maximum Cl− removal rates of 61.8% and 66.1% are respectively achieved under the optimum conditions. The higher removal efficiency of the magnetite Bi-Ti composite is contributed by its less stable crystal phases of Bi25FeO40/Bi12TiO20, which can proceed more deeply in the removal of Cl− ions compared with that of Bi2O3. The recovered terminal magnetite Bi-Ti precipitate with Bi2O3/BiOCl heterostructure exhibits excellent photocatalytic activity in the degradation of the dechlorinated leachate, where a total organic carbon removal rate of 87.2% is achieved under UV–vis-near-infrared irradiation. Therefore, the selection of Bi(III) containing oxides opens a promising and high-value method for the removal and recovery of Cl− ions in leachate and other waste waters.

Molecular characteristics governing chlorine deposition and removal on promoted Ag catalysts during ethylene epoxidation

The selectivity of Ag ethylene epoxidation catalysts correlates with surface coverage of the promoter chlorine. Cl coverage, in turn, is a function of co-fed organic chloride and alkane moderator pressures. Organic molecules can be classified based on their deprotonation enthalpy, as those that are inert, those capable of selective oxidation, or those that act as gas-phase acids. The influence of alkane moderator and alkyl chloride promoter identities on Cl coverage was assessed by titration of Cl by ethane in a recirculating gas-phase batch reactor immediately following steady-state reactions with various alkane and alkyl chlorides included in ethylene oxidation feedstreams. The faculty of organic molecules for Cl removal correlates with the weakest CH bond dissociation enthalpy, such that molecules with CH bonds susceptible to homolysis remove Cl more effectively than those with stronger CH bonds. Cl deposition likely occurs via heterolytic cleavage of CCl bonds in alkyl chlorides, such that molecules with weak CCl bonds deposit multiple monolayers of Cl. Cl coverage affects ethylene epoxidation rates identically regardless of the organic chloride or the aliphatic hydrocarbon employed, demonstrating that these molecules only impact catalysis by moderating Cl coverage. These findings implicate the concurrent prevalence of homolytic and heterolytic pathways during ethylene epoxidation on promoted Ag/α-Al2O3 catalysts and provide context to examine additional roles of surface oxygen beyond involvement in oxidation pathways.

The interaction between ionic liquids (ILs) and an enriched ammonia oxidising bacteria (AOB) culture

Ionic liquids (ILs) have attracted attention in recent years due to their “greener” properties compared to conventional organic solvents. However, they may still pose a risk to the environment as their toxicity is not fully understood. Bioremediation of such ILs can be an economically and environmentally friendly approach. Therefore, this study aims to examine the interaction of three ILs (1-dodecylpyridnium chloride [DPy]+Cl, 1-Butyl-3-methylimidazolium chloride [BMIm]+Cl, and 1-Carbamoylmethyl pyridinium chloride [CMPy]+Cl) at different concentrations with an enriched ammonia oxidising bacteria (AOB) culture, and investigate their effects on the ammonia oxidation rate (AOR) as well as their removal and transformation. The results indicated that the longer chain IL [DPy]+Cl had a negative effect on the AOR while [BMIm]+Cl and [CMPy]+Cl enhanced the AOR. However, the IL removal rates displayed the opposite results as [DPy]+Cl was observed with the highest removal. It was found that biosorption played a major role in [DPy]+Cl removal. Biotransformation products for each IL were identified and their pathways were proposed. This study demonstrated that although longer chain ILs have a greater degree of removal, and they are also more toxic to AOB at higher concentration.

Trace Element Mass Flow Rates from U.S. Coal Fired Power Plants.

Trace elements (TEs) exit coal-fired power plants (CFPPs) via solid, liquid, and gaseous waste streams. Estimating the TE concentrations of these waste streams is essential to selecting pollution controls and estimating emission reduction benefits. This work introduces a generalizable mass balance model for estimating TE mass flow rates in CFPP waste streams and evaluates model accuracy for the U.S. coal fleet given current data constraints. We stochastically estimate, using a bootstrapping approach, the 2015 plant-level mass flow rates of Hg, Se, As, and Cl to solid, liquid, and gas phase waste streams by combining publicly available data for combusted coal TE concentrations with estimates of TE partitioning within installed air pollution control processes. When compared with measured and reported data on TE mass flow rates, this model generally overestimates masses by 30-50%, with larger errors for Hg. The partitioning estimates are consistent for Se, As, and Cl removal from flue gas, but tend to underestimate Hg removal. While our model is suitable for first-order estimates of TE mass flows, future work to improve model performance should focus on collecting and using new data on TE concentrations in the coal blend, where data quality is the weakest.

Treatment of Saline Water Using Electrocoagulation with Combined Electrical Connection of Electrodes

Saline water treatment has become increasingly important for drinking water supplies. The aim of this study was to evaluate the ability of the electrocoagulation (EC) process with combined aluminum electrodes in removing various types of salt from water samples collected at Sawa Lake, Al-Muthanna, Iraq. The targeted types of salt include total dissolved solids (TDS), chloride salt (Cl−), bromine (Br−), and sulphate (SO42−). A bench scale consisting of combined EC configurations with static electrodes was employed under combined electrical connections. The effect of the six variables factors, such as applied current density (I), reaction time (RT), pH, temperature (T), stirring speed (Mrpm) and inter electrode distance (IED) were observed to achieve a higher removal of TDS, Cl−, Br− and SO42−. Initial results showed the following optimum operating conditions: I = 2 mA/cm2, RT = 80 min, pH = 8, T = 25 °C, IED = 1 cm and Mrpm = 500. The maximum removal efficiency of TDS, Cl−, Br− and SO42− were 91%, 93%, 92% and 90%, respectively. It can be concluded that the EC method applied in the present study was effective to removing salts from lake water.

Effect of Cl Removal in MSWI Bottom Ash via Carbonation with CO<sub>2</sub> and Decomposition Kinetics of Friedel’s Salt

Effect of Cl Removal in MSWI Bottom Ash via Carbonation with CO<sub>2</sub> and Decomposition Kinetics of Friedel’s Salt

Molecular mechanisms of caffeine-mediated intestinal epithelial ion transports.

As little is known about the effect of caffeine, one of the most widely consumed substances worldwide, on intestinal function, we aimed to study its action on intestinal anion secretion and the underlying molecular mechanisms. Anion secretion and channel expression were examined in mouse duodenal epithelium by Ussing chambers and immunocytochemistry. Ca2+ imaging was also performed in intestinal epithelial cells (IECs). Caffeine (10mM) markedly increased mouse duodenal short-circuit current (Isc ), which was attenuated by a removal of either Cl- or HCO3 - , Ca2+ -free serosal solutions and selective blockers of store-operated Ca2+ channels (SOC/Ca2+ release-activated Ca2+ channels), and knockdown of Orai1 channels on the serosal side of duodenal tissues. Caffeine induced SOC entry in IEC, which was inhibited by ruthenium red and selective blockers of SOC. Caffeine-stimulated duodenal Isc was inhibited by the endoplasmic reticulum Ca2+ chelator (N,N,N',N'-tetrakis(2-pyridylmethyl)ethylenediamine), selective blockers (ruthenium red and dantrolene) of ryanodine receptors (RyR), and of Ca2+ -activated Cl- channels (niflumic acid and T16A). There was synergism between cAMP and Ca2+ signalling, in which cAMP/PKA promoted caffeine/Ca2+ -mediated anion secretion. Expression of STIM1 and Orai1 was detected in mouse duodenal mucosa and human IECs. The Orai1 proteins were primarily co-located with the basolateral marker Na+ , K+ -ATPase. Caffeine stimulated intestinal anion secretion mainly through the RyR/Orai1/Ca2+ signalling pathway. There is synergism between cAMP/PKA and caffeine/Ca2+ -mediated anion secretion. Our findings suggest that a caffeine-mediated RyR/Orai1/Ca2+ pathway could provide novel potential drug targets to control intestinal anion secretion.

Effects of water leaching (simulated rainfall) and additives (KOH, KCl, and SiO2) on the ash fusion characteristics of corn straw

To solve the intractable slagging problem during biomass combustion, natural leaching by rainfall is an economy and effective post-harvest quality optimization method. The effects of simulated rainfall intensity and duration on the removals of ash, K and Cl, and consequently the ash fusion temperature (AFTs) of corn straw were studied. Meanwhile, the effects of KOH, KCl, and SiO2 additives were compared. Leaching reduced the formation of KCl and K2SO4 in biomass ash effectively and thus the formation of low-melting K2O·nSiO2 (n = 1–4), whereas the relatively content of high-melting SiO2 increased, resulting in increased AFTs. Leaching intensity had stronger effects than leaching duration. There exists a critical leaching point at ∼4 ml water consumption per gram biomass, after which continued leaching had less removal efficiencies. During the initial leaching stage (with a water consumption of 2–4 ml per gram biomass), less removal of Cl compared to K2O caused lower IDT and ST, but higher FT; consequently, the extended temperature difference deteriorates deposition formation. A raninfall/snow leaching influencing mechanism on biomass AFTs was illustrated. These results provide useful guidelines for choosing the appropriate time node of straw collection in field based on rainfall, and thus reducing slagging during biomass combustion.

Functional Role of Basolateral ClC-2 Channels in the Regulation of Duodenal Anion Secretion in Mice.

Although ClC-2 channels are important in colonic Cl- secretion, it is unclear about their roles in small intestinal anion secretion. Therefore, we sought to examine whether ClC-2 channels play important roles in anion secretion, particularly duodenal bicarbonate secretion (DBS). Duodenal mucosae from mice were stripped of seromuscular layers and mounted in Ussing chambers. Both duodenal short-circuit current (Isc) and HCO3- secretion in vitro were simultaneously recorded. DBS in vivo was measured by a CO2-sensitive electrode. Lubiprostone, a selective ClC-2 activator, concentration-dependently increased both duodenal Isc and DBS only when applied basolaterally, but not when applied apically. Removal of extracellular Cl- abolished lubiprostone-induced duodenal Isc, but did not alter HCO3- secretion even in the presence of DIDS, a Cl-/HCO3- exchanger inhibitor. However, further addition of glibenclamide, a CFTR channel blocker, abolished lubiprostone-evoked HCO3- secretion. Moreover, lubiprostone-induced HCO3- secretion was impaired in CFTR-/- mice compared to wild-type littermates. Luminal perfusion of duodenal lumen with lubiprostone did not alter basal DBS in vivo, but lubiprostone (i.p.) was able to induce DBS, which was also significantly inhibited by Cd2+, a ClC-2 channel blocker. [Ca2+]cyt level, Ca2+-activated K+ channel- and cAMP-mediated duodenal Isc, and HCO3- secretion were unchanged by lubiprostone. We have provided the first evidence for the novel functional role of basolateral ClC-2 channels in the regulation of duodenal anion secretion.

Water recovery via the removal of Cl− ion and total dissolved solids using electrodialysis in Gohar Zamin Iron Ore Concentrate Plant (GIOCP): modeling and simulation

The desalination process consists of a set of multi-step actions, which are conducted on saline water in order to remove excess salts and other minerals. In the desalination process, water is recovered, so that it would be suitable for industrial usage. In the present study, electrodialysis (ED) was used for desalination, especially for removing chloride (Cl-) ion and total dissolved solids (TDS), in Gohar Zamin Iron Ore Concentrate Plant (GIOCP). To optimize the influential factors in the removal of chloride and TDS in ED, the response surface methodology (RSM) was utilized. To this end, the D-optimal experimental design was applied to optimize the experiments. The effects of three independent parameters, including electrolysis time (A), consumption voltage (B), and initial concentration of chloride ion (C), were assess for the removal of chloride and TDS from recovered water. In addition, interactive and linear models were applied to determine the responses of chloride and TDS removal rates, respectively. The optimal operating conditions for the removal of chloride with 51.46% efficiency were obtained at the runtime of 30 minutes, consumption voltage of 12 V, and initial concentration of 300 ppm. Similarly, optimal TDS removal with 48.03% efficiency was achieved at the runtime of 30 minutes, consumption voltage of 12 V, and initial concentration of 300 ppm. According to the findings, ED was a highly reliable method for the removal of salts from water, as well as the high-quality recycling of water from mineral industries, especially in mineral processing plants.

Effect of torrefaction on rice straw physicochemical characteristics and particulate matter emission behavior during combustion

In this work, the effects of different torrefaction temperatures and durations on the physicochemical properties of rice straw (RS), and the emission characteristic of PM10 (particulate matter with aerodynamic diameters of ≤10 µm) during torrefied RS combustion, were investigated. Results indicate that the release of Cl and K, and decomposition of the organic matrix demonstrated a promoting effect during torrefaction. However, the removal of Cl and K did not reduce the emission of PM1. The emission concentration of PM1 and PM1–10 generated from torrefied RS was enhanced, and the yields of PM1–10 was much higher than those of PM1. The concentrations of K and Cl in PM1–10 increased with torrefaction temperature, combined with the microstructure, indicating that the torrefaction pretreatment promoted the heterogeneous condensation of KCl vapour to form PM1–10.

Landfill leachate treatment by sorption in magnetic particles: preliminary study

Leachates are still an open issue in environmental protection. Many of the applied methods for their treatment present low efficiency and thus need to be used collectively. In practice reverse osmosis is mostly used, as it is the most effective option, regardless of its cost. Magnetic methods to treat effluents have been used for water and wastewater treatment by the use of magnetic particles together with magnetic separation for the removal of contaminants. However, large-scale applications are few or even non-existent when we deal with complex contaminated media such as landfill leachates, for which not even research studies at laboratorial scale with real samples have been done yet. In this work, we apply for the first time magnetic sorption for the treatment of leachates, and close the full cycle by studying the regeneration and re-use of the magnetic particles; we also study the influence of the concentration of magnetic particles, the use of several pre-treatment methodologies and the type of particle used in the process, in real landfill samples from the waste treatment plant of Salamanca (Spain), for the removal of COD, NO3−, NO2−, NH4+, Total-N, PO43−, SO42− and Cl−. Regeneration of the magnetic particles after being used in the sorption stage is also studied, as well as their efficiency regarding their re-use. It is also determined the optimum number of batches for complete desorption and for regeneration of the particles, the effect of successive regeneration and re-use cycles, the use of two different regeneration methods, the efficiency of the desorption, the effect of the quantity of solvent and the influence of the time of sorption. Due to its innovative character and the complexity of the media, this work represents a first preliminary approach and, although some promising results have been obtained, further studies are required to completely understand and evaluate the proposed treatment process.

The sensing reaction on the Ni-NiO (111) surface at atomic and molecule level and migration of electron

NiO octahedrons with capped Cl− ions were synthesized by heating aqueous NiCl2 solution at 400 °C. The as-synthesized cubic phase NiO octahedrons are enclosed by {111} surfaces. For acetone, formaldehyde, triethylamine and ethanol, the NiO octahedrons show higher responses than NiO particles, and their responses are significantly increased by removing the surface Cl− ions and −OH groups. The Sr of the hydrogenated NiO octahedrons is 1.46, 1.50, 2.34 and 1.53 towards 50 ppm of acetone, formaldehyde, triethylamine and ethanol, respectively. The excellent sensing properties are attributed to the increased the quantity of 3-coordinated unsaturated Ni atoms on the Ni-NiO surface through removal of Cl− ions and −OH groups. The 3-coordinated unsaturated Ni atoms are considered to serve as a sensing reaction active site, and a gas sensing reaction mechanism is presented at the atomic and molecule level. The 3-coordinated unsaturated Ni atoms can absorb O2 molecules, generate free electrons and catalyze the reaction between the absorb O2 with the detected gas. The sensing mechanism of 3-coordinated unsaturated Ni atoms serving as the reaction active sites will be useful for the understanding of sensing and other catalytic reaction mechanisms as well as the design and fabrication of advanced gas sensing materials and catalysts.

Reversibility of Graphene Photochlorination

The reversibility of graphene photochemical chlorination was investigated. A high content of Cl is obtained through photochlorination, without changing C hybridization. To accommodate the incorporated Cl, graphene corrugation takes place. However, due to weak bonding, Cl atoms desorb during air exposure and long periods of storage. Chlorination also leads to graphene doping. When Cl is removed, doping decreases and graphene returns to its original morphology. Only a small amount of Cl (Cl/C ∼ 0.1) remains strongly bonded to graphene, most likely at grain edges and defects. Therefore, to maintain a precise doping level, Cl trapping methods are essential. Moreover, Cl removal using laser irradiation can be used to tune doping in micrometric areas, making it a promising technique to be used in applications where different doping levels are needed.

Petrogenesis and Assembly of the Don Manuel Igneous Complex, Miocene–Pliocene Porphyry Copper Belt, Central Chile

The 4·0–3·6 Ma Don Manuel igneous complex (DMIC), central Chile, provides a window into igneous processes involved in magma genesis associated with porphyry-style copper mineralization. This study uses petrographic, petrological, geochemical and isotopic data to examine the evolution of magmas from the mid- to lower-crustal source region to shallow emplacement. The data provide evidence for progressive oxidation of magma during differentiation and ascent, fractionation of Cl from S through degassing, and the late-stage, near-solidus removal of Cl from the system. Magmas of basaltic andesite to rhyolite composition were produced by polybaric differentiation of hydrous parental mafic magmas. Variations in crustal differentiation depths led to variable suppression of plagioclase saturation that is recorded in distinctive strontium versus anorthite evolution patterns. Hydrous, derivative magmas generated over a wide range of pressures were episodically emplaced into the shallow crust at depths between 3·5 and 5 km. Intermediate porphyry dikes closely associated with copper mineralization contain diverse crystal cargoes indicating significant magma mixing. These crystal cargoes represent samples of crystal mush entrained from different depths, as well as crystals originating in different magmas and crystals grown in situ from hybridized magmas. Mafic enclaves containing plagioclase and amphibole compositions that match those of the basaltic andesites occur within biotite tonalite, testifying to magma mingling during ascent. Sulfur and chlorine contents of apatite within the different DMIC units record variable degassing and decoupling of volatile components with sulfur showing variations of three orders of magnitude compared with one order of magnitude for chlorine. The hypabyssal nature of the DMIC affords a detailed, integrated record of magmatic differentiation processes occurring within trans-crustal magmatic systems of the sort thought to characterize many crustal arc settings and play a fundamental role in driving porphyry-style copper mineralization.

Chloride Ion Removal from the Wet Flue Gas Desulfurization and Denitrification Wastewater Using Friedel’s Salt Precipitation Method

The desulfurization and denitrification wastewater (DDW) from the wet flue gas treatment project is difficult to be treated and recycled because of high chloride ion (Cl−) concentration. Cl− can cause equipment and piping corrosion. However, there is a lack of cost-effective treatment technologies for the removal of Cl− from the DDW. In this research, the feasibility of Cl− removal from the DDW using Friedel’s salt precipitation method was evaluated. Factors affecting the Cl− removal, such as Ca(OH)2 dosage, NaAlO2 dosage, solution’s initial pH, solution’s temperature, reaction time, stirring speed, and anions (SO42−, NO3−, and F−), were investigated, and the optimal experimental conditions for Cl− removal were determined. Experimental results showed that Friedel’s salt precipitation method can remove Cl− effectively and can achieve synergistic removal of SO42−, F−, and heavy metal ions. Under the best experimental conditions, the average removal efficiencies of Cl−, SO42−, F−, and heavy metal ions reach more than 85%, 98%, 94%, and 99%, respectively. The Cl− removal mechanism studies showed that Cl− can be removed by precipitation as Ca4Al2Cl2(OH)12. The purified wastewater and the precipitated solid can be reused to reduce the consumption of water and alkali. Friedel’s salt precipitation method is an effective control technology for the synergistic removal of Cl−, SO42−, F−, and heavy metal ions and has enormous potential to be applied in the industrial wastewater treatment field.

Molecular Basis and Differentiation-Associated Alterations of Anion Secretion in Human Duodenal Enteroid Monolayers

Background & AimsHuman enteroids present a novel tool to study human intestinal ion transport physiology and pathophysiology. The present study describes the contributions of Cl- and HCO3- secretion to total cyclic adenosine monophosphate (cAMP)-stimulated electrogenic anion secretion in human duodenal enteroid monolayers and the relevant changes after differentiation.MethodsHuman duodenal enteroids derived from 4 donors were grown as monolayers and differentiated by a protocol that includes the removal of Wnt3A, R-spondin1, and SB202190 for 5 days. The messenger RNA level and protein expression of selected ion transporters and carbonic anhydrase isoforms were determined by quantitative real-time polymerase chain reaction and immunoblotting, respectively. Undifferentiated and differentiated enteroid monolayers were mounted in the Ussing chamber/voltage-current clamp apparatus, using solutions that contained as well as lacked Cl- and HCO3-/CO2, to determine the magnitude of forskolin-induced short-circuit current change and its sensitivity to specific inhibitors that target selected ion transporters and carbonic anhydrase(s).ResultsDifferentiation resulted in a significant reduction in the messenger RNA level and protein expression of cystic fibrosis transmembrane conductance regulator, (CFTR) Na+/K+/2Cl- co-transporter 1 (NKCC1), and potassium channel, voltage gated, subfamily E, regulatory subunit 3 (KCNE3); and, conversely, increase of down-regulated-in-adenoma (DRA), electrogenic Na+/HCO3- co-transporter 1 (NBCe1), carbonic anhydrase 2 (CA2), and carbonic anhydrase 4 (CA4). Both undifferentiated and differentiated enteroids showed active cAMP-stimulated anion secretion that included both Cl- and HCO3- secretion as the magnitude of total active anion secretion was reduced after the removal of extracellular Cl- or HCO3-/CO2. The magnitude of total anion secretion in differentiated enteroids was approximately 33% of that in undifferentiated enteroids, primarily owing to the reduction in Cl- secretion with no significant change in HCO3- secretion. Anion secretion was consistently lower but detectable in differentiated enteroids compared with undifferentiated enteroids in the absence of extracellular Cl- or HCO3-/CO2. Inhibiting CFTR, NKCC1, carbonic anhydrase(s), cAMP-activated K+ channel(s), and Na+/K+-adenosine triphosphatase reduced cAMP-stimulated anion secretion in both undifferentiated and differentiated enteroids.ConclusionsHuman enteroids recapitulate anion secretion physiology of small intestinal epithelium. Enteroid differentiation is associated with significant alterations in the expression of several ion transporters and carbonic anhydrase isoforms, leading to a reduced but preserved anion secretory phenotype owing to markedly reduced Cl- secretion but no significant change in HCO3- secretion.