Chemical Separation Processes Research Articles

Improved N2O capture performance of chromium terephthalate MIL-101 via substituent engineering

The capture of N2O from CO2 by an adsorption-based mechanism remains a significant challenge due to their similar molecular sizes and physical properties. Although substituent engineering has been widely employed for the selectivity regulation and improvement of gas mixtures in metal-organic frameworks, its effect on N2O/CO2 separation has yet not been explored. Herein, four isoreticular MTN-type metal-organic frameworks (MOFs) with different substituents (-H, –NH2, -Br or –NO2) are reported for the capture of N2O from a N2O/CO2 mixture. As revealed by isothermal measurements, thermodynamic studies and ideal adsorbed solution theory computations, the N2O/CO2 separation potential can be effectively improved by an electron-donating group (-NH2), whereas electron-withdrawing groups (-NO2 or -Br) exhibit the opposite effect. Notably, MIL-101(Cr)–NH2 exhibits, by far, the highest ideal adsorbed solution theory equilibrium adsorption selectivity of 1.91 for 50/50 N2O/CO2. The N2O/N2 separation ability of the modified materials is also studied and functionalization with a -Br group yields an improved separation potential compared to the parent MIL-101(Cr) material. The strategy of using substituents to enhance the N2O/CO2 separation efficiency of MOFs could also be extended to other porous materials for chemical separation processes.

Low-Field Functional Group Resolved Nuclear Spin Relaxation in Mesoporous Silica.

Solid-fluid interactions underpin the efficacy of functional porous materials across a diverse array of chemical reaction and separation processes. However, detailed characterization of interfacial phenomena within such systems is hampered by their optically opaque nature. Motivated by the need to bridge this capability gap, we report low-magnetic-field two-dimensional (2D) 1H nuclear spin relaxation measurements as a noninvasive probe of adsorbate identity and interfacial dynamics, exploring the relaxation characteristics exhibited by liquid hydrocarbon adsorbates confined to a model mesoporous silica. For the first time, we demonstrate the capacity of this approach in distinguishing functional group-specific relaxation phenomena across a diverse range of alcohols and carboxylic acids employed as solvents, reagents, and liquid hydrogen carriers, with distinct relaxation responses assigned to the alkyl and hydroxyl moieties of each confined liquid. Uniquely, this relaxation behavior is shown to correlate with adsorbate acidity, with the observed relationship rationalized on the basis of surface-adsorbate proton-exchange dynamics. Our results demonstrate that nuclear spin relaxation provides a molecular-level perspective on sorbent/sorbate interactions, motivating the exploration of such measurements as a unique probe of adsorbate identity within optically opaque porous media.

Numerical Study on the Ferrofluid Droplet Splitting in a T-junction with Branches of Unequal Widths using Asymmetric Magnetic Field

Research on the microdroplet splitting phenomenon has intensified in recent years. Microdroplet splitting has numerous applications in chemical synthesis, biology, and separation processes. The current paper covers the numerical study of ferrofluid microdroplet splitting at various lengths and velocities inside the T-junction with branches of unequal widths under asymmetric magnetic fields. Microdroplet splitting can be controlled by using an asymmetric magnetic field and the asymmetry in the width of T-junctions branches. Three geometrical models of the T-junction with different widths ratio (0.7, 0.85, and 1), along with a magnetic field with various intensities are studied. This magnetic field is generated by a line dipole. In this study, the distance between the dipole and origin is kept constant. The splitting ratio of ferrofluid microdroplets at different velocities (different capillary numbers), different non-dimensional lengths and different magnetic force (different magnetic Bond numbers) at the center of T-junction are calculated for each amount of branch width. The results are verified with previous works and their correctness is proved. The splitting ratio is defined as the volumetric ratio of the larger daughter droplet to the mother droplet. The results indicate that generally, the stronger the asymmetric magnetic force is, the more asymmetric the splitting will become, with the splitting ratio becoming closer to 1. Also, as asymmetry increases between the widths of the two branches of the T-junction, the splitting ratio approaches 1.

Computer-Aided Molecular Design of Optimal Sustainable Solvent for Liquid-Liquid Extraction

The selection of suitable solvents for chemical separation processes has been a challenging task as substantial amount of time and resources are required. Computer-aided molecular design (CAMD) has facilitated the search for novel solvents by providing a more efficient and systematic pathway to synthesize optimal solvents. Solvent properties such as selectivity and capacity often exhibit opposed behavior which are known as antagonistic properties. The antagonistic properties of solvent are addressed where the major highlight of this work is that a compromise between selectivity and capacity can be achieved by introducing mixture design. Hildebrand solubility parameters are introduced as screening criteria to determine the potential molecular building blocks, which possess the desired functionality and properties of solvent. UNIFAC group contribution method is implemented for the prediction of liquid-phase activity coefficient, which is equivalent to inverse of the mole fraction solubility. The increasing attention on sustainability aspects is also addressed by introducing safety and health (SE) parameters as design criteria, where index-based approach is implemented to quantify these parameters. Analytical hierarchy process (AHP) is then introduced to deal with the subjectivity in defining relative importance of these SE parameters. The mixture design problem is formulated along with SE parameters as a multi-objective optimization model where an integrated Bi-Level AHP optimization model is introduced to solve this model. A case study on the extraction of 1,2-dichloroethane from cyclohexane is studied to implement the developed CAMD framework in the search of optimal solvent for liquid-liquid extraction process.

A novel two-parts heat integrated dividing wall column with middle vapor recompression

The intensified heat integrated technology can be applied to the distillation column to improve the utilization of energy resources in the chemical separation processes. For further improving the energy efficiency of the hydrocarbon mixture distillation separation process, a novel two-parts heat integrated dividing wall column (DWC) with middle vapor recompression (MVRC) is proposed in this paper. Differed by the position of vapor recompression, above or beneath the dividing wall in the column, two configurations of MVRC assisted DWC (MVRC-DWC) were developed and comprehensively evaluated by energy, exergy, economic and environmental impact (4E) analysis, with comparison to the existing vapor recompression assisted dividing wall column (VRC-DWC) and a very competitive improved heat integration of VRC-DWC (IHI-VRC-DWC). Moreover, the heat integration between the pre-separated column and different DWC configurations are carefully designed and also evaluated by 4E analysis. Comparatively, the CRS-MVRC-DWC can supply more latent heat of the vapor to the pre-separated column, consequently the process has the largest energy saving and lowest exergy consumption and exergy loss than the other configurations. The TAC saving of process with CRS-MVRC-DWC can reach to the highest value of 25.72%.

Evaluation of the redox capability of manganese‑titanium mixed oxides for thermochemical energy storage and chemical looping processes

Manganese oxides are capable of releasing molecular oxygen and regenerate in air under determined conditions. This fact makes these materials interesting for applications in different areas, such as thermochemical energy storage processes, oxygen production by chemical looping air separation (CLAS) or CO2 capture-oriented processes, namely chemical looping combustion (CLC) or chemical looping with oxygen uncoupling (CLOU).In this work, the potential to release molecular oxygen and regenerate in air of different manganese‑titanium mixed oxides with mass fractions of titanium from 0 to 50%, were evaluated in a TGA apparatus. Besides, the reactivity of the mixed oxide samples to the main fuel gases (CO, H2 and CH4) has been also evaluated. Consecutive redox cycles have been performed at different temperatures (850 and 940 °C) using nitrogen during reduction and air in oxidation. The oxygen transport capacity as well as the rate index for oxygen uncoupling and gas-solid reactions have been determined and compared to that found for other materials reported in literature. Moreover, solid phase identification in the different mixed oxide samples by XRD has been addressed in order to determine the oxygen release/regeneration mechanism. Results show a great potential of these materials as low-cost and environmentally friendly oxygen carriers.

Polymerization and Transformation of Tungsten(VI) Species in Acidic Aqueous Solution by Electrospray Ionization Time-of-Flight Mass Spectrometry

Deep understanding of the polymerization and transformation of tungstate species in aqueous solution is of great significance for hydrometallurgical and chemical separation processes, such as solvent extraction, membrane separation and crystallization. In order to study the polymerization and transformation of tungstate species, the semi-quantitative characterization method of electrospray ionization time-of-flight mass spectrometry (ESI-TOF-MS) was developed. In this paper, the tungsten speciation in simulative leaching solution was investigated in detail between pH 2.5 and 7 under various conditions (e.g. acid species, initial concentration, pH), and the results indicated that HCl was more conducive than HNO3 for the polymerization of tungsten at the same pH, and HAc accelerated the polymerization of tungsten species, especially in acid solution at lower pH; the morphological changes of each tungsten species tended to be consistent with the increase of tungsten concentration; pH strongly influenced the distribution of tungsten species. Then, the polymerization and transformation laws of tungstate species are summarized. W1 (monomers) are dominant species in weak acid and neutral solution, and aggregate into oligomeric species (e.g. W2, W4, W6). Transformations also exist among W2, W4 and W6. The polymerization process from W4 and W6 species to higher poly-tungstate (W10–12) was observed with the consumption of H+. This work aims to understand the polymerization and transformation of tungsten speciation using ESI-TOF-MS, which should provide useful information for the understanding and optimizing of industrial production and environmental processes, building a bridge between micro tungsten speciation and macro industrial applications.

Changes in carbon pools and enzyme activities in soil amended with pig slurry derived from different feeding diets and filtration process

Monitoring soil carbon content and pools and associated enzyme activities has become an important area of research in terms of the carbon cycle in agricultural lands in order to infer factors regulating soil carbon sequestration. Pig slurry (PS) is considered as a source of organic matter and nutrients for crop production. In recent years, because of the cost of conventional feed applications, manufacturers have preferred liquid feeding diets with decreases of 10–25% in production costs. Furthermore, physical and chemical filtration of PS by new techniques may prevent soil degradation and reduce the negative effects of PS, such as high salt, pathogen, and heavy metal contents. This research aimed to assess the effect of the application of raw pig slurry (R) and treated pig slurry (T) (derived from physical and chemical separation processes) from liquid (L) and solid (S) feeding diets on different soil organic carbon pools and enzyme activities in a sandy loam soil under a rainfed barley cropping system for two years. The solid diet consisted of maize/soya bean, tubers and roots, and supplementary vitamins and minerals. The liquid diet consisted of dairy products such as fresh whey, concentrated cheese or yogurt, skim milk powder, and beer by-products such as brewer's yeast. As a general pattern, the addition of the different types of PS (R or T) had no significant effect on most soil properties, except for microbial biomass C (Cmic), which increased with R. However, the type of diet did have a significant effect on most properties, both for R or T slurries, suggesting that this is more of a determinant factor in explaining changes in soil than the type of pig slurry. Solid diet favors the significant increase of soil organic carbon and arylesterase activity, suggesting higher stabilization of the organic compounds provided by the PS. However, the liquid diet contributed to increasing soluble C and Cmic, suggesting higher availability of nutrients and C sources. Hence, the use of treated pig slurry has no detrimental effect on organic carbon dynamics compared to raw pig slurry and can be suggested as an alternative to reduce the environmental impact, prevent soil pollution, and ensure sustainability.

Microgeometry-independent equation for measuring infinite dilution activity coefficients using gas-liquid chromatography with static-wall-coated open-tubular columns

Gas-liquid chromatography is an effective method to determine infinite dilution activity coefficients (γ∞). Wall-coated open-tubular (WCOT) column which offers more advantages over packed column should be a preferable column type; however, the small carrier gas flow rate and stationary phase amount in WCOT columns limit its application in the determination of γ∞. Mathematical strategy made some progress to avoid the quantification problem in the determination of γ∞ by static-wall-coated open-tubular (SWCOT) columns. However, the previously reported strategy was based on the assumption that SWCOT column was geometrically an ideal hollow cylinder, which indeed deviates from the reality. In this study, without that assumption, we derived a new microgeometry-independent equation by using the relationship between the hold-up volume (VM) and the volume of stationary phase (VL), and used it to measure the γ∞ of various organic solutes in two ionic liquids (ILs) 1‑butyl‑3-methylimidazolium dicyanamide and 1,3-dibutyronitrile-imidazolium bis((trifluoromethyl)sulfonyl)imide, both of which contain double cyano groups in the anion or cation. Phase loading study was adopted to eliminate the influence of interfacial adsorption to partition. The infinite dilution partial molar excess enthalpy, selectivity and capacity were directly calculated from the experimental γ∞ values, and the linear solvation energy relationship (LSER) model was used to characterize the specific properties of both ILs. This new established equation will promote the application of SWCOT columns in thermodynamic measurement and benefit the fast screening of novel solvents for chemical separation processes.

Large anisotropic negative thermal expansion in Cu-TDPAT metal-organic framework: A combined in situ X-ray diffraction and DRIFTS study

Cu-TDPAT (H6TDPAT = 2,4,6-tris(3,5-dicarboxylphenylamino)-1,3,5-triazine), a stable nanoporous metal-organic framework with rht topology, has sparked broad interest as an adsorbent for several chemical separation processes. In this work, in situ synchrotron diffraction experiments followed by sequential LeBail refinements reveal that Cu-TDPAT shows unusually large anisotropic negative thermal expansion (NTE). The PASCal crystallography tool, used to analyze the magnitude of the NTE, reveals an average volumetric thermal expansion coefficient αv = −20.3 MK−1. This value is significantly higher than the one reported for Cu-BTC (also known as HKUST-1), which contains the same Cu-paddlewheel building unit, αv ≈ −12 MK−1. In situ synchrotron single crystal X-ray diffraction and in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) were employed to shed light on the NTE mechanism. Using these two methods, we were able to elucidate the three main structural motions that are responsible for the NTE effect. The more pronounced NTE behavior of Cu-TDPAT is attributed to the lower symmetry combined with the more complex ligand structure when compared to Cu-BTC. The knowledge obtained in this work is important for understanding the behavior of the adsorbent under transient variable temperature conditions in fixed adsorption beds.

UNIFAC Model for Ionic Liquids. 2. Revision and Extension

Ionic liquids (ILs) as separating agents have been extensively studied in chemical separation processes. For IL-containing systems, the UNIFAC model for ILs (i.e., UNIFAC-Lei model) has become a po...

Hydrogen cyanide recovery by membrane gas separation

Hydrogen cyanide is an important feedstock in many chemical industries, synthesized from natural gas and ammonia. To recovery unreacted ammonia and purify the hydrogen cyanide from water and hydrogen, additional chemical separation processes are required. The conventional approach is to undertake these separations through solvent absorption; but gas separation membranes are a competitive alternative. This investigation examines the potential for membrane gas separation to replace solvent absorption in hydrogen cyanide processing. Importantly, the HCN permeability through a range of common polymeric membranes were measured and resulting HCN selectivity reported. Rubbery polymeric membranes’ permeability strongly correlated with condensability of the gases, and therefore in HCN processing the order of permeability was H2O > H2 ≈ HCN > N2. In contrast, glassy polymeric membranes’ permeability correlated with kinetic diameter of the gases, and permeability order was H2O > H2 > HCN ≈ N2. The presence of N2 in the gas stream however presented a challenge, as the similar permeability between N2 and HCN meant that separation of these two gases was difficult. A facilitated transport mechanism was developed based on metal chlorides within both glassy and rubbery polymeric membranes. The complexation between the hydrogen cyanide and the metal ion increased the concentration of HCN within the polymeric membrane and facilitated the permeation of HCN. Zinc chloride demonstrated a clear increase in HCN permeability and improved HCN/N2 selectivity for the two membranes studied. This improvement was further enhanced by the presence of water vapour, which augmented the complexation between HCN and the metal ion, achieving an order of magnitude increase in selectivity. Hence, this investigation demonstrated the potential for membrane gas separation to compete in hydrogen cyanide processing.

Separation of nanoparticles via surfing on chemical wavefronts.

The separation of micro and nanoscale colloids is a necessary step in most biological microassay techniques, and is a common practice in microchemical processing. Chemical waves are frequently encountered in biochemical systems driven far from equilibrium. Here, we put forward a strategy for separating small suspending colloids by means of their surfing on substrate chemical wavefronts. The colloids with catalytic activities sensitive to the substrates are activated to show self-propulsion and consequently exhibit a chemotactic response to the traveling wavefronts, which results in their spontaneous separation from the multicomponent complex mixture via self-diffusiophoresis. The dynamics of the process is analyzed through a particle-based simulation. In addition, it is found that separation can be carried out according to particle size. The mechanisms underpinning the chemical and physical separation processes are discussed, and the dependencies on the reaction rate constant and particle size are presented. The results may prove relevant for further experimental and theoretical studies of separation in complex active environments.

A Production Challenge of Ac-225 from RaCO3 Target Activated by Vertical Beam

Ac-225 (t1/2 = 10 d) is regarded as a promising alpha emitter for the targeted alpha therapy (TAT). Considering biodistribution of conjugated antibodies, as well as logistics in worldwide supply, a physical half-life of 10 days would be tolerable for keeping certain radioactivity in each case. Actinium shows a good compatibility to DOTA that is favorable in radiochemistry to enhance the fusion of diagnosis and therapeutic studies including novel radiopharmaceuticals development. However, the current capability of Ac-225 supply is very limited at around 2 Ci/year that mainly relies on the natural source of Th-229 stocked in a few institutes; therefore, any artificial production ways of Ac-225 would be highly desired. Among possible channels of Ac-225 production, protons on Ra-226 (t1/2 = 1600 y) is the sole option we can employ practically, due to the accessibility of target material under the current regulation in our country/institute and high cross-section of this reaction that can be performed on medical cyclotron platforms. Radium-226 used in this study was originated from 1–4 mCi of ‘legacy needles’, presumably being filled as sulfate or bromide with or without carrier Ba, and we successfully collected soluble Ra in HCl followed by the Ref [1]. Then, enriched 40CaCO3 (as carrier), ammonium solution (to make pH>9) and (NH4)2CO3 (to precipitate) in turn were added into 100–500 μCi of Ra/HCl to obtain practically insoluble radium carbonate. The sediment contained RaCO3 was isolated on a filter made of silicon carbide to make Ra target disk, which can be activated directly at our vertical beam station owing to the heat and chemical resistance of SiC, as well as gravity-supported target holding. Irradiations were performed with 18 MeV protons at 3 μA for 3 h (on target 16.7 MeV). The activated target, allowed to decay for about 3 days, was dissolved in 1 M HCl, and then purified to obtain Ac-225 fraction as the final product. Production yield of Ac-225 was roughly estimated to be about 1/200 of Ra-226 activity by this activation condition (1.6 μCi of Ac-225 at the EOB from 360 μCi of Ra-226, in average). Ac-226 (T1/2 = 29 h) was the primal impurity found in our sample that was about 30% with regards to the activity of Ac-225, corrected to the EOB. Although our study is still in development, we concluded that the Ac-225 production from Ra-226 target is feasible that could give sufficient quantity and quality of Ac-225 also in a scaled-up condition with appropriate energy window, cooling time and chemical separation processes. This work was partially supported by JSPS Grant-in-Aid for Scientific Research (C), Grant Number 17K10384. [1]Matyskin, A.V. et al. J. Radioanal. Nucl. Chem. 310 (2016) 589–595.

Низкотемпературное разделение и концентрирование в условиях образования гетерогенных систем (обзор)

В обзоре рассмотрены современные подходы, используемые в методах разделения и концентрирования биологически активных соединений в условиях образования гетерогенных систем при низких температурах. Обсуждены факторы, позволяющие повысить эффективность низкотемпературной жидкостно-жидкостной экстракции, криоконцентрирования, экстракционного вымораживания. Рассмотрены возможные механизмы физико-химических сепарационных процессов, реализуемых в условиях низких температур.

Application of retrofitted design and optimization framework based on the exergy analysis to a crude oil distillation plant

The petroleum refining industry is one of the most complex and energy-intensive separation units that produce various petroleum products from crude oil. In this work, an entire crude oil distillation unit (CDU) process is retrofitted and optimized by a proposed theoretical retrofit-optimization framework based on established exergy loss analysis. The purpose of this analysis is to further improve the energy utilization efficiency of the process both qualitatively quantitatively. The theoretical derivation is carried out on exergy loss of key components in CDU including condensers, furnaces, and distillation columns. The locations and magnitudes of the inefficiency in the whole process are detected according to the exergy loss distribution analysis of the basic process. The exergy loss of every studied sub-unit is defined as the objective function to be minimized in the optimization of key operational parameters using the Sequential Quadratic Programming (SQP) methodology. Compared to the basic process, the exergy efficiency of improved process is increased from 28.9% to 41.4%, and the total annual consumption (TAC) is reduced by 28.7% under the same flow rates and qualities of every product. The proposed framework is able to be extended to other similar chemical separation processes to achieve a higher energy and exergy saving.

A Production Challenge of Ac-225 from RaCO3 Target Activated by Vertical Beam

Ac-225 (t1/2 = 10 d) is regarded as a promising alpha emitter for the targeted alpha therapy (TAT). Considering biodistribution of conjugated antibodies, as well as logistics in worldwide supply, a physical half-life of 10 days would be tolerable for keeping certain radioactivity in each case. Actinium shows a good compatibility to DOTA that is favorable in radiochemistry to enhance the fusion of diagnosis and therapeutic studies including novel radiopharmaceuticals development. However, the current capability of Ac-225 supply is very limited at around 2 Ci/year that mainly relies on the natural source of Th-229 stocked in a few institutes; therefore, any artificial production ways of Ac-225 would be highly desired. Among possible channels of Ac-225 production, protons on Ra-226 (t1/2 = 1600 y) is the sole option we can employ practically, due to the accessibility of target material under the current regulation in our country/institute and high cross-section of this reaction that can be performed on medical cyclotron platforms. Radium-226 used in this study was originated from 1–4 mCi of ‘legacy needles’, presumably being filled as sulfate or bromide with or without carrier Ba, and we successfully collected soluble Ra in HCl followed by the Ref [1]. Then, enriched 40CaCO3 (as carrier), ammonium solution (to make pH>9) and (NH4)2CO3 (to precipitate) in turn were added into 100–500 μCi of Ra/HCl to obtain practically insoluble radium carbonate. The sediment contained RaCO3 was isolated on a filter made of silicon carbide to make Ra target disk, which can be activated directly at our vertical beam station owing to the heat and chemical resistance of SiC, as well as gravity-supported target holding. Irradiations were performed with 18 MeV protons at 3 μA for 3 h (on target 16.7 MeV). The activated target, allowed to decay for about 3 days, was dissolved in 1 M HCl, and then purified to obtain Ac-225 fraction as the final product. Production yield of Ac-225 was roughly estimated to be about 1/200 of Ra-226 activity by this activation condition (1.6 μCi of Ac-225 at the EOB from 360 μCi of Ra-226, in average). Ac-226 (T1/2 = 29 h) was the primal impurity found in our sample that was about 30% with regards to the activity of Ac-225, corrected to the EOB. Although our study is still in development, we concluded that the Ac-225 production from Ra-226 target is feasible that could give sufficient quantity and quality of Ac-225 also in a scaled-up condition with appropriate energy window, cooling time and chemical separation processes. This work was partially supported by JSPS Grant-in-Aid for Scientific Research (C), Grant Number 17K10384. [1]Matyskin, A.V. et al. J. Radioanal. Nucl. Chem. 310 (2016) 589–595.

Recovery of sterols from vegetable oil distillate by enzymatic and non-enzymatic processes

Sterols are a group of molecules found in plants and animals, which have a number of valuable applications. The deodorization residue, referred to as “deodistillate”, was previously considered as a waste but its economical value nowadays increased due to the presence of high concentrations of sterols, tocopherols and other secondary metabolites attractive for the cosmetic, pharmaceutical or food industry. Sterols can be extracted from vegetable oil deodistillate through a variety of physical and chemical separation processes or their combination. Recently, the use of lipase enzymes has been demonstrated to separate sterols more selectively in higher yields and in milder conditions. This article reviews these lipase-assisted sterol extractions and their main advantages and drawbacks in economic and environmental terms. • Sterol extraction from vegetable oil deodistillate. • Reviewing on enzymatic process to involve extraction. • Different strategies are discussed in an industrial operation approach.

Bioremediation of Nitrate Reduction Present in Leather Industries Effluent by using Marine Algae

Nitrogen occurs naturally under oxidation of nitric anhydride, N 2 O 5 and nitrates, NO 3- and also from ammonia, and ammonium ions, NH 4 +. Because of increase in human activities environmental nitrate concentrations also increased which leads to introduction of large quantities of nitrates into ground and surface waters. Agriculture is the major source of nitrate pollution because of using of nitrogen-containing fertilizers, concentrated livestock and poultry farming. Nitrates are also released from the industrial production of glass, explosives, as well as from various chemical production and separation processes. Highest reduction in nitrate content was found in benzene extract of U.lactuca 91% and very minimal reduction of 12 % was found in aqueous extract of E.intestinalis . Among all, the extracts of Ulva lactuca, Enteromorpha flexuosa fell under Category A (Good reduction), and benzene was found to be the best solvent system. Maximum reduction by powdered algae was found in C.antenina collected from Covelong and Puduchery (375 mg/l).

Preparation of poly(2,4,6‐triaminopyrimidine‐TMC)/P84 composite nanofiltration membrane with enhanced chlorine resistance and solvent resistance

AbstractBACKGROUNDNanofiltration membrane has attracted great study interest because of its high permselectivity and low operating cost. However, most commercial nanofiltration membranes are still not applicable for chemical separation processes due to their low resistance to organic solvent and chlorination.RESULTS2,4,6‐triaminopyrimidine (TAPI) was employed as an aqueous phase monomer to prepare poly (2,4,6‐triaminopyrimidine‐TMC) composite nanofiltration membrane with interfacial polymerization. Polyimide (P84) ultrafiltration (UF) membrane was crosslinked with TAPI and used as the supporting membrane. The composite membrane showed high rejection (91.4%) of Na2SO4 and a high flux (7.3 L m−2 h−1) at 0.3 MPa and ambient temperature. The membrane also showed high stability during 120 h immersion in N,N‐dimethylacetamide (DMAc) and acetone. The performance of membrane immersed in 200 ppm NaClO solution did not decline over 96 h.CONCLUSIONTAPI with reactive amino group can be used as aqueous phase monomer to prepare poly (2,4,6‐triaminopyrimidine‐TMC) composite nanofiltration membrane with high permselectivity. The pyrimidine ring of TAPI endows the functional layer with excellent chlorine resistance while the crosslinking of P84 membrane with TAPI significantly improves the solvent resistance. © 2018 Society of Chemical Industry