Centrosymmetric RbSnF2NO3 vs. Noncentrosymmetric Rb2SbF3(NO3)2

Two fluoride nitrates named RbSnF2NO3 and Rb2SbF3(NO3)2 have been successfully synthesized using a rapid evaporation concentration method by introducing Sn2+/Sb3+ cations with the stereochemically active lone pairs into the nitrates...

Ultrafast laser micro-nano structured superhydrophobic teflon surfaces for enhanced SERS detection via evaporation concentration

Evaporation concentration of target analytes dissolved in a water droplet based on superhydrophobic surfaces could be able to break the limits for sensitive trace substance detection techniques (e.g. SERS) and it is promising in the fields such as food safety, eco-pollution, and bioscience. In the present study, polytetrafluoroethylene (PTFE) surfaces were processed by femtosecond laser and the corresponding processing parameter combinations were optimised to obtain surfaces with excellent superhydrophobicity. The optimal parameter combination is: laser power: 6.4 W; scanning spacing: 40 μm; scanning number: 1; and scanning path: 90 degree. For trapping and localising droplets, a tiny square area in the middle of the surface remained unprocessed for each sample. The evaporation and concentration processes of droplets on the optimised surfaces were performed and analyzed, respectively. It is shown that the droplets with targeted solute can successfully collect all solute into the designed trapping areas during evaporation process on our laser fabricated superhydrophobic surface, resulting in detection domains with high solute concentration for SERS characterisation. It is shown that the detected peak intensity of rhodamine 6G with a concentration of 10−6m in SERS characterisation can be obviously enhanced by one or two orders of magnitude on the laser fabricated surfaces compared with that of the unprocessed blank samples.

Hydrogeochemical Characteristics of Fluoride in the Groundwater of Shuangliao City, China

This study investigated the hydrogeochemical characteristics of fluoride in the groundwater of Shuangliao City. This paper analyzes the effects of different forms of hydrochemistry and the chemical speciation of fluorine in water. The results showed that an area of high fluorine was located in the northern section of Shuangliao City, and the soil salinization degree was also high in this area. The chemical composition of groundwater was mainly formed by the evaporation-concentration process; both pH (weak alkaline environment) and total dissolved solids (TDS) had a positive effect on fluorine enrichment within a certain range; Na+ and F- had significant positive correlation, HCO3- and F- had a weak positive correlation, and Ca2+ was the only ion with a negative correlation with F-.

Characterization of Origin and Evolution of Formation Water in Buried Hill of Jizhong Depression, China, Using Multivariate Statistical Analysis of Geochemical Data

Groundwater samples from buried hill of Jizhong Depression were evaluated using two statistical analyses: hierarchical cluster analysis (HCA) and principal component analysis (PCA). The samples were classified into four clusters, C1–C4, in HCA and the hydrochemical types of C1–C4 are HCO3-Na, Cl·HCO3-Na, Cl-Na, and Cl-Na·Ca. From C1 to C2, C3, and C4, the water-rock interaction becomes increasingly intensive, and rNa/rCl gets lower while total dissolved solids and r(Cl-Na)/rMg get higher. Three components of PCA explain 86.87% of the variance. Component1 (PC1), characterized by highly positive loadings in Na+ and Cl−, is related to evaporation concentration. Component2 (PC2) is defined by highly positive loading in HCO3- and is related to influence of atmospheric water. With high positive loadings in Ca2+ and high negative loadings in Na+ and SO42-, component3 (PC3) suggests plagioclase albitization. The combination of HCA and PCA within the hydrogeological contexts allowed the division of study area into five dynamic areas. From recharge area to discharge area, the influence of atmospheric water gets weaker and water-rock interactions such as evaporation concentration and plagioclase albitization become intensive. Therefore groundwater in buried hill showed paths of hydrochemical evolution, from C1, to C2, C3, and C4. Buried hill reservoir in Jizhong Depression is mainly distributed in hydrodynamic blocking and discharge area; therefore the two regions can be the favorable areas for petroleum migration.

Study on the Salt Precipitation Law of La Guocuo Salt Lake Brine with Pretreatment at 5°C

The brine from La Guocuo was pretreated with adding magnesium chloride hexahydrate, and it evaporated at 5°C. The salt precipitation law is obtained by evaporation experiment of this pretreated brine. In the evaporation concentration process, the salts precipitate phases are successively: magnesium carbonate, sodium sulfate, borate salts, sodium chloride and glaserite.

Evaluation of the Combined Process of Aammonia Distillation-Evaporation Concentration - Supercritical Water Gasification - Supercritical Water Oxidation for Coking Wastewater Treatment

A combined process of ammonia distillation - evaporation concentration - supercritical water gasification (SCWG) supercritical water oxidation (SCWO) was proposed for coking wastewater treatment. The NH3 in wastewater was first recovered in ammonia distillation section. The deammoniated wastewater was concentrated in the evaporation concentration section, in which the quantity of the wastewater was decreased accordingly. Then the concentrated wastewater entered into the SCWG section to produce the syngas such as H2, CO, CH4, and liquid effluent entered into SCWO section, where the pollutants were completely degraded. The operation parameters of the combined process were simulated by Aspen Plus software and the investment and the operation cost were also analyzed. For a wastewater of 5000kg/h, the investment of the combined process is 6000000 ¥. The profit from byproduct of ammonia, syngas and steam is 70¥/t. For the whole process, it can gain a profit of 5.1 ¥/t (wastewater).