Effects of Functionalized Silica Nanoparticles on Characteristics of Nanocomposites PES Cation Exchange Membranes

Nanocomposite cation exchange membranes（CEMs） were prepared by adding various loadings of functionalized silica nanoparticles to the sulfonated polyethersulfone（s PES） polymeric matrix. The silica nanoparticles were functionalized by mercaptopropyl（F1, IEC=0）, propylsulfonic acid（F2, IEC= 2.71）, and sulfonic acid（F3, IEC=2.84）. The properties of prepared membranes were investigated by varying the loadings of functionalized silica nanoparticles. Applying functionalized nanoparticles provides additional ion exchange groups and enhances water contents as well as conductivities and permselectivities of the membranes. The maximum IEC of 1.9 meq.g^-1 was obtained for the membrane having 3 wt% F3 nanoparticles and the maximum conductivity of 0.237 S·cm^-1 was achieved for the membrane having 2 wt% F3 nanoparticles, which were 19.6% and 64% higher than the corresponding values for s PES membrane, respectively. The excellent properties of the nanocomposite cation-exchange membranes make them appropriate candidates for electrodialysis and desalination processes.

Assessment of Cation Exchange Membrane Method and Estimation of Potassium Critical Values

Soil and tissue analyses are usually used in identifying potassium(K) deficiencies and predicting K fertilizer requirements of crops.The critical levels of both soil and fresh leaf tissue at seventh leaf stage were developed and assessed for canola,chickpea and sunflower grown on two Saskatchewan,soils,with six rates of K fertilizer supply, in a growth chamber experiment.The available potassium in soils was determined by two methods:1)resin strip extraction, and 2) NH4OAC extraction. The potassium in fresh leaves was determined at seventh leaf stage by a simple procedure using a common garlic press and injector to extract the plant sap and testing the sap with a handheld ion selection electrode meter. The results shoWed significant relationships between the resin strip extractable K and NH4OAC extractable K, and between the plant uptake of total K and the supply of available K in the soils determined by the two methods. Good relationships were also found between the potassium in fresh leaves and the plant uptake of total K for canola, chickpea and sunflower.The resin strip extraction for K was calibrated using common NH4OAC extraction, and recommended for routine analyses because of its simplicity and sensitivity.

Use of Cation Exchange Membrane in Soil Potassium Release and Wheat Response to Potassinm

A pot experiment was conducted in the growth chamber on Saskatchewan soils with dfferent texture todeterniine the K release status and wheat K demand. The relationship between K uptake and soil availableK extracted by cation exchange membrane (CEM-K) and the effect of K fertilizer on wheat growth and soilavailable K was also evaluated. Theatments of 0, 60 and 120 mg K/kg were applied to sandy, low and highK loamy and clay soils. The highest yields were achieved with the application of 120 mg K/kg in sandysoil and 60 mg K/kg in other soils. On the whole, the clay soil contributed K more than other soils fromslowly available fraction. Regression revealed a linear relationship between the soil available K extractedby NH_4OAc(Ka) and CEM-K in suspensions (r=0.93). Results also showed that CEM-K in burial and insuspensions were different not only in the amount but also in correlation with Ka or K uptake.

Optimizing functional layer of cation exchange membrane by three-dimensional cross-linking quaternization for enhancing monovalent selectivity

Monovalent cation perm-selective membrane(MCPMs)allow fast and selective transport of monovalent cations,and they are promisingly required for extraction of special ions,such as lithium extraction,acid recovery and sea salt production.Herein,we report a novel strategy to design the critical functional layers of MCPMs with both space charge repulsion and cross-linked dense screenability.The in-situ depo-sition polymerization of pyrrole was carried out on the surface of sulfonated polyphenyl sulfone(SPPSU)substrate membrane followed by cross-linking quaternization of the polypyrrole(PPy)layer with diiodi-nated functional molecules,thus,the membrane obtained more excellent selective permeability and sta-ble transport properties of monovalent cations.It confirms that the designed PPy layers with charged sur-face and cross-linking structure improved the hydrophilicity,facilitated cation transport and increased ion flux.Meanwhile,for the dense PPy layer,the charged cross-linked structure endowed the functional layer with the synergistic characteristics of Donnan exclusion and pore size sieving for positively charged ions,which improved the monovalent cation perm-selectivity of the membranes.At a constant current density of 5.1 mA/cm^(2),the optimal membrane exhibited superior perm-selectivity(P^(Na)_(Mg)=2.07)and monovalent cation flux(J_(Na+)=2.80×10^(−8)mol cm^(−2)s^(−1))during electrodialysis.

Electrodeposition of cobalt in double-membrane three-compartment electrolytic reactor

The process parameters were optimized for the electrodeposition of cobalt from cobalt chloride solution in the membrane electrolytic reactor. Effects of parameters such as catholyte composition, current density and temperature on the current efficiency, specific power consumption and quality of deposition were studied. The catholyte was a mixed solution of cobalt chloride, the initial middle electrolyte consisted of diluted hydrochloric acid, and the anolyte was sulfuric acid. An anion exchange membrane separated the catholyte from the middle electrolyte, and a cation exchange membrane separated the anolyte from the middle electrolyte. The results showed that a maximum current efficiency of 97.5% was attained under the optimum experimental condition of an catholyte composition of 80 g/L Co^2＋, 20 g/L H3BO3, 3 g/L NaF and pH of 4, at a cathode current density of 250 A/m2 and a temperature of 50 ℃ HCl could be produced in the middle compartment electrochemically up to 0.45 mol/L.

Aviation-oriented Micromachining Technology—Micro-ECM in Pure Water

This article proposes a precise and ecofriendly micromachining technology for aerospace application called electrochemical machining in pure water （PW-ECM）. On the basis of the principles of water dissociation, a series of test setups and tests are devised and performed under different conditions. These tests explain the need for technological conditions realizing PW-ECM, and further explore the technological principles. The results from the tests demonstrate a successful removal of electrolytic slime by means of ultrasonic vibration of the workpiece. To ensure the stability and reliability of PW-ECM process, a new combined machining method of PW-ECM assisted with ultrasonic vibration （PW-ECM/USV） is devised. Trilateral and square cavities and holes as well as a group of English alphabets are worked out on a stainless steel plate. It is confirmed that PW-ECM will be probably an efficient new aviation precision machining method.

Ion Exchange Membrane“ABC”–A Key Material for Upgrading Process Industries

Ion exchange membrane plays a crucial role in transforming and upgrading traditional chemical manufacturing procedures and boosting a multitude of new applications.Due to the strict regulations on wastewater discharge and increasing demands of renewable energy,anion exchange membrane(“A”membrane),bipolar membrane(“B”membrane)and cation exchange membrane(“C”membrane)have become a key material for upgrading various process industries.Herein,we summarized several novel synthetic routes for“ABC”membranes fabrication from the viewpoints of designing novel membrane synthetic routes,regulating the ionic transport channels,imparting dynamic transfer regions,introducing intrinsic micro-porosity into the membrane and among others.The account includes a brief introduction to membrane structure designs and fabrications,emerging and industrial applications,and perspectives on ion exchange membranes.