Estimating EC and ionic EC contribution percentage of nutrient solution based on ionic activity

The dynamic monitoring technology of inorganic ions using ion selective electrodes has some problems such as low precision,vulnerability to other ions,short service life,and high price.Due to the difficulty of dynamic control based on ionic concentration of nutrient solution,EC and pH values of nutrient solution are often used as feedback control indexes in hydroponic system.In this study,estimation algorisms of EC and ionic EC contribution percentage based on ionic activity were proposed to understand the quantitative relationship between ionic concentration and EC.With a view to predicting the EC accurately by mean ionic activities of specific salts in nutrient solution based on a specific formula,ionic concentration could also be calculated by the actual measurement of EC combined with ionic EC contribution percentage.With Japanese horticultural experimental nutrient formula and Yamasaki tomato nutrient formula,significant linear correlations between estimated EC and measured EC were found with determination coefficients over 0.99.Ionic EC contribution percentage was not affected by different relative concentrations of nutrient solutions.However,ionic EC contribution percentage changed significantly when adding specific salts with different concentrations,and different changes were found in each anions and cations of specific salt added.When the same K+concentration was added in different forms of KNO_(3),K_(2_SO_(4),KCl,and KH_(2)PO_(4),the changes of ionic EC contribution percentage of K^(+)were similar,but those of other anions in potassium salts varied greatly.The relative errors of estimated EC of nutrient solutions based on ionic activities were only 1.3%in horticultural experimental nutrient solution and 1.8%in Yamasaki tomato nutrient solution with different relative concentrations compared to measured EC.The relative errors of estimated EC of nutrient solutions with specific salt added were only 0.1%-0.5%compared to measured EC in two nutrient solution.Therefore,the dynamic feedback control of ionic concentration of nutrient solution could be realized by using EC measurement combined with ionic EC contribution percentage to improve the ionic quantitative control in nutrient solution.The EC control of nutrient solution in automatic irrigation system might be upgraded to ionic concentration control by using algorisms above of ionic EC contribution percentage and EC estimation to meet dynamic demands of hydroponic crops for ionic concentration in different growth stages.

A theoretical exploration of the influencing factors for surface potential

Although it has been widely used to probe the interracial property, dynamics, and reactivity, the surface potential remains intractable for directly being measured, especially for charged particles in aqueous solutions. This paper presents that the surface potential is strongly dependent on the Hofmeister effect, and the theory including ion polarization and ionic correlation shows significant improvement compared with the classical theory. Ion polarization causes a strong Hofmeister effect and further dramatic decrease to surface potential, especially at low concentration; in contrast, ionic correlation that is closely associated with potential decay distance overestimates surface potential and plays an increasing role at higher ionic concentrations. Contributions of ion polarization and ionic correlation are respectively assessed, and a critical point is detected where their contributions can be exactly counteracted. Ionic correlation can be almost neglected at low ionic concentrations, while ion polarization, albeit less important at high concentrations, should be considered across the entire concentration range. The results thus obtained are applicable to other interfacial processes.

Modified DIX model for ion-exchange equilibrium of L-phenylalanine on a strong cation-exchange resin

L-phenylalanine, one of the nine essential amino acids for the human body, is extensively used as an ingredient in food, pharmaceutical and nutrition industries. A suitable equilibrium model is required for purification of L-phenylalanine based on ion-exchange chromatography. In this work, the equilibrium uptake of L-phenylalanine on a strong acid-cation exchanger SH11 was investigated experimentally and theoretically. A modified Donnan ion-exchange （DIX） model, which takes the activiW into account, was established to predict the uptake of L-phenylalanine at various solution pH values. The model parameters including selectivity and mean activity coefficient in the resin phase are presented. The modified DIX model is in good agreement with the experimental data. The optimum operating pH value of 2.0, with the highest t-phenylalanine uptake on the resin, is predicted by the model. This basic information combined with the general mass transfer model will lay the foundation for the prediction of dynamic behavior of fixed bed separation process.

An expedient one-pot synthesis of highly substituted imidazoles using supported ionic liquid-like phase(SILLP) as a green and effcient catalyst and evaluation of their anti-microbial activity

An effcient method for the synthesis of imidazole derivatives by a three-component condensation of benzil or 9,10-phenanthrenequinone,aldehydes and ammonium acetate using supported ionic liquidlike phase（SILLP）catalyst under ultrasonic irradiation or classical heating conditions is reported.The present methodology offers several advantages,such as excellent yields,simple procedures,short reaction times,simple work-up and mild conditions.The catalyst is easily separated from the products by fltration and also exhibits remarkable reusable activity.These highly substituted imidazoles were also evaluated for their anti-microbial activity.

Vanadium-Doped Magnesium Oxide Nanoparticles Formation in Presence of Ionic Liquids and Their Use in Photocatalytic Degradation of Methylene Blue

Magnesium oxide（MgO） is one of the metal oxides having unique properties with numerous potential industrial applications.In this study,MgO and vanadium-doped MgO nanoparticles were synthesized by sol–gel method in 1-butyl-3-methylimidazolium tetrafluoroborate [BMIM][BF_4] and 1-octyl-3-methylimidazolium tetrafluoroborate [OMIM][BF_4] ionic liquids.Vanadium-doped MgO nanoparticles exhibited nanosphere and nanorod morphologies with 40–80 nm in particle size,primarily due to the influence of ionic liquids as demonstrated by high-resolution scanning electron microscopy and transmission electron microscopy.Characteristics of nanoparticles were also studied by thermal gravimetric analysis,X-ray diffraction and energy-dispersive X-ray spectroscopy.Photodegradation ability of synthesized nanoparticles was evaluated for methylene blue（MB） in specially designed UV reactor.Photodegradation is found to be dependent on doping,and particle characteristics change due to the influence of ionic liquid.The ionic liquid-assisted vanadium-doped MgO nanoparticles showed good reusability under UV irradiation and MB degradation ability under visible light.