Post-synthetic derivatization of graphitic carbon nitride with methanesulfonyl chloride: Synthesis, characterization and photocatalysis

Bulk graphitic carbon nitride (CN) was synthetized by heating of melamine at 550 degrees C, and the exfoliated CN (ExCN) was prepared by heating of CN at 500 degrees C. Sulfur-doped CN was synthesized by heating of thiourea (S-CN) and by a novel procedure based on the post-synthetic derivatization of CN with methanesulfonyl (CH3SO2-) chloride (Mes-CN and Mes-ExCN). The obtained nanomaterials were investigated by common characterization methods and their photocatalytic activity was tested by means of the decomposition of acetic orange 7 (AO7) under ultraviolet A (UVA) irradiation. The content of sulfur in the modified CN decreased in the sequence of Mes-ExCN > Mes-CN > S-CN. The absorption of light decreased in the opposite manner, but no influence on the band gap energies was observed. The methanesulfonyl (mesyl) groups connected to primary and secondary amine groups were confirmed by high resolution mass spectrometry (HRMS). The photocatalytic activity decreased in the sequence of Mes-ExCN > ExCN > CN approximate to Mes-CN > S-CN. The highest activity of Mes-ExCN and ExCN was explained by the highest amounts of adsorbed Acetic Orange 7 (AO7). In addition, in the case of Mes-ExCN, chloride ions incorporated in the CN lattice enhanced the photocatalytic activity as well.Web of Science102art. no. 19

Liquid Phase Behavior in Systems of 1-Butyl-3-alkylimidazolium bis{(trifluoromethyl)sulfonyl}imide Ionic Liquids with Water: Influence of the Structure of the C5 Alkyl Substituent

International audienceIn the present paper a study of the liquid phase behavior in aqueous systems of imidazolium-based ionic liquids (ILs) with the bis{(trifluoromethyl)sulfonyl}imide anion is addressed. To highlight the influence of the C5 alkyl side group structure on their properties, a series of ILs with linear, branched, and cyclic substituents was studied. As was already shown in our previous work, very subtle changes in the cation structure at the molecular scale can have a significant and unexpected impact on the bulk properties. Therefore, in this work, the mutual solubilities of 1-butyl-3-alkylimidazolium bis{(trifluoromethyl)sulfonyl}imide ionic liquids and water were studied, both experimentally and by modeling, at atmospheric pressure as a function of temperature from 293.15 to 328.15 K. The solubilities of the ionic liquids in water are very low, typically around 10−5 mole fraction units and were measured by a direct analytical method, making use of UV–Vis spectrophotometry. The solubilities of water in the ionic liquids were found to be around 0.20 mole fraction units and were measured using the cloud-point method. In addition to the experimental data, the liquid–liquid equilibria in the systems were modeled using the COSMO-RS methodology. Phase diagrams and the critical solution points were also estimated by applying the universal scaling laws based on the 3D Ising model, taking into account the non-linearity of the diameter and crossover to mean-field behavior

Table_1_Botanical and microbial insecticides application in aquaponics - is there a risk for biofilter bacteria and fish?.docx

Aquaponics is a food production system that combines aquaculture with hydroponics. The simultaneous existence of fish, beneficial bacteria and plants in the same water loop predisposes the fish and bacteria to a possible detrimental effect of plant protection products. Additionally, there is an inadequate exploration of scientific studies on the impact of pesticides on fish and bacteria in aquaponics systems. This study investigated the effects of three commercial insecticides based on the following active ingredients: pyrethrum, azadirachtin, and spinosad, on aquaponics systems. Due to ethical concerns in animal testing, applying insecticides directly to aquaponics setup was impossible. Therefore, three separate experiments were conducted: (1) Pesticide runoff rate – in which insecticides were applied to basil (Ocimum basilicum) plants grown in two hydroponic systems: media bed and floating raft. The concentrations of applied insecticides were measured in the water of nutrient solutions of the hydroponics after 1, 3, 6, 12, 24, 36, 48, 72 and 96h to establish a pattern of degradation of insecticides. The result from this experiment showed that pyrethrum and spinosad were detected in unquantifiable concentrations in the nutrient solutions. Hence, further experiments were conducted only with azadirachtin. In a biofilter trial (2) – azadirachtin, at three concentrations (1.5 µg L-1; 7.5 µg L-1; and 15 µg L-1), was added to a running biofilter to investigate the effects on nitrifying bacteria. Mild effects were recorded in the nitrification and bacteria microbiome. In the third trial (3) – Nile tilapia (Oreochromis niloticus) were exposed to similar concentrations of azadirachtin for seven days (and the same period for recovery) to investigate effects on fish hematology, blood biochemistry, antioxidative enzymes in the brain, gills, muscle, liver and intestine and histopathology of gills and liver. Results showed mild effects in hematology and biochemistry profile in fish and higher levels of lipid peroxidation in the liver during the exposure. The results indicate a safe use of pyrethrum and spinosad in aquaponics setup, while azadirachtin has to be used with care, especially in coupled aquaponics systems.</p