Holothuria tubulosa as a bioindicator to analyse metal pollution on the coast of Alicante (Spain)

Metal pollution is a major concern worldwide. The concentration of several metals in marine sediments from Alicante, Spain (Western Mediterranean): Cabo de la Huerta, Albufereta, San Gabriel and Cabo de Santa Pola has been studied, being areas with contrasted metal stress due to anthropogenic pressures, and their bioaccumulation in different tissues of Holothuria tubulosa (body wall, guts and intestine). The metals with more different levels among samples were Fe, Al, V, Mn, Pb, Ga, As, Cr, Zn and B. The body wall was the tissue that showed a significantly different signature of metal levels compared to the other body parts and the sediment. The guts, followed by the intestines, were the tissues with greatest bioaccumulation. The standard guidelines for safety limits (US EPA) for As, Cr, Pb and Zn are in the range “non-polluted”. In all the areas, the quality guidelines for Effect Level, Probable Effect Level, Effect Range Low and Effect Range Medium for As, Cr, Pb and Zn are much lower than those established, indicating no biologically adverse effects resulting from exposure to these metals. Regarding the potential ecological risk, for all metals it is <40 with low risk in all zones. The metals studied present a negative Igeo (area not contaminated). Arsenic in Albufereta and strontium in all the areas studied are the only ones that present a level 2 (uncontaminated to moderately contaminated). The Enrichment Factor (EF), with Fe as the normalising element, had a level 1–3 (minor enrichment), with the exception of Pb, B, As and Sr. Despite the concentrations in sediments being lower compared with other parts of the world, the Biota-Sediment Assimilation Factor from the body wall was higher at As (9.2) and B (7.3). It is necessary to highlight the high levels of As in the body wall (17 to 23 mg/kg of dry material), this is surprising, and it seems to be a general trend throughout the world.The authors wish to thank the Generalitat Valenciana (Spain) for the financial help of the Project CIAICO/2021. This study was partially financed by the University of Alicante’s Chemical Engineering Department, Marine Sciences & Applied Biology Department and University Institute of Water and Environmental Sciences (IUACA)

CaSO4 solubility in water–ethanol mixtures in the presence of sodium chloride at 25 °C. Application to a reverse osmosis process

Nowadays, the most common way to desalinate seawater is by reverse osmosis. As the degree of conversion during this process increases more freshwater is recovered from the feedwater. As a result, the salt concentration in the feed increases up to a point where the solubility limit could be reached. Experimentally, it is known that adding an organic substance such as ethanol to salty water induces salt precipitation. This work investigated the solid–liquid equilibrium of the system water–ethanol–NaCl–CaSO4 at 25 °C. Results show that as the ethanol content is increased CaSO4 solubility decreases. On the other hand, brine from the reverse osmosis plant at the University of Alicante was treated with ethanol to precipitate calcium sulfate and produce brine containing less calcium and sulfate. The treated brine was analyzed and its calcium content was compared with the predicted value based on the experimental data. The results suggest that it is possible to use ethanol to precipitate the salts from brine in order to obtain a higher degree of conversion in a reverse osmosis process. The obvious limitation of the method is the cost of recovering the ethanol by separation

Influence of the Temperature on the Liquid–Liquid–Solid Equilibria of the Water + Ethanol + 1-Undecanol Ternary System

Liquid–liquid (L–L), solid–liquid (S–L), and solid–liquid–liquid (S–L–L) equilibrium data for the water–ethanol–1-undecanol ternary system have been determined experimentally at (275.15, 278.15, 281.15, 288.15, and 298.15) K and atmospheric pressure. Different shapes of the equilibrium diagrams have been observed depending on the temperature. A region with three phases (S–L–L) is present in the temperature range between (275.15 and 281.15) K. Above 288.15 K, only a L–L region is observed.We thank the University of Alicante (Spain) for the financial support

Liquid–Liquid, Vapor–Liquid, and Vapor–Liquid–Liquid Equilibrium Data for the Water–n-Butanol–Cyclohexane System at Atmospheric Pressure: Experimental Determination and Correlation

The temperature and the composition of the vapor–liquid–liquid equilibrium (VLLE) and the vapor–liquid equilibrium (VLE) of a ternary mixture of water–n-butanol–cyclohexane were measured at atmospheric pressure (101.32 kPa) in a modified dynamic recirculating still. As found in the literature, the experimental data obtained reveal a ternary azeotrope at 341.86 K with a mole fraction composition of 0.281, 0.034, and 0.685 water, n-butanol, and cyclohexane, respectively. The liquid–liquid equilibrium (LLE) compositions were measured at a constant temperature of 313.15 K and compared with data in the literature collected at other temperatures. Thermodynamic consistency of all the experimental data was demonstrated. The universal quasichemical (UNIQUAC) and the nonrandom two-liquid (NRTL) thermodynamic models were used to correlate the VLE and LLE data, while the original universal functional (UNIFAC) model was used to compare the predicted data.The authors thank the DGICYT of Spain for the financial support of project CTQ2009-13770

Phase equilibria of the water + 1-butanol + toluene ternary system at 101.3 kPa

Isobaric vapour–liquid and vapour–liquid–liquid equilibrium data for the water + 1-butanol + toluene ternary system were measured at 101.3 kPa with a modified VLE 602 Fischer apparatus. In addition, the liquid–liquid equilibrium data at 313.15 K were measured and compared with data from other authors at different temperatures. The system exhibits a ternary heterogeneous azeotrope whose temperature and composition have been determined by interpolation. The thermodynamic consistency of the experimental vapour–liquid and vapour–liquid–liquid data was checked by means of the Wisniak’s Li/Wi consistency test. Moreover, the vapour–liquid and the liquid–liquid equilibrium correlation for the ternary system with NRTL and UNIQUAC models, together with the prediction made with the UNIFAC model, were studied and discussed.The authors thank the DGICYT of Spain for the financial support of project CTQ2009-13770

Experimental study of the LL, VL and VLL equilibria of water + 1-butanol + 2-octanol at 101.3 kPa

Equilibrium data for the water + 1-butanol + 2-octanol system is determined in this work. Liquid-liquid equilibrium (LLE) data are obtained at 303.15 K and 313.15 K, with a view to investigating the influence of temperature. Vapour-liquid-liquid equilibrium (VLLE) and vapour-liquid equilibrium (VLE) data of the same system are also determined at 101.3 kPa, by means of a modified Fisher Labodest recirculating still that is coupled to an ultrasonic probe. Additionally, the heterogeneous binary azeotrope of the pair water + 2-octanol is determined. Correlation parameters are obtained from the experimental results for use in the universal quasichemical (UNIQUAC) and non-random two-liquid (NRTL) thermodynamic models in CHEMCAD 7. The UNIQUAC, NRTL and original universal functional group activity coefficient (UNIFAC) models are then, in turn, used to predict the LLE and VLLE data from these correlation parameters.The authors wish to thank the Conselleria d'Educació, Investigació, Cultura i Esport (Generalitat Valenciana) of Spain for the financial support of project AICO/2015/052

Forced precipitation experiments for study of the electromagnetic treatment of water

The objective of this research is to know the effect of the electromagnetic equipment TK3K to prevention of incrustations in pipes. A method of forced precipitation of calcium carbonate, mixing solutions of Ca(NO3)2 and Na2CO3 with tap water, shows differences in the temporal evolution of turbidity, absorbance and in the final size of the particles formed, which makes it possible to distinguish between treated and untreated water. The latter present higher values ​​of parameters analyzed than the treated ones. A longer treatment time does not produce different results, while an increase in temperature causes a greater decrease. Since there is no immediate technique on the market to verify the effect of electromagnetic treatment, this method, with temperature control, is simple and fast.This study was carried out thanks to the financial support of the Generalitat Valenciana (FEDEGENT/2018/005) and the company ECOTÉCNICA ENERGY SYSTEMS S.L

Consistency of experimental data in SLLV equilibrium of ternary systems with electrolyte. Application to the water + NaCl + 2-propanol system at 101.3 kPa

The SLLV phase equilibria of the water + NaCl + 2-propanol mixture have been determined experimentally at 101.3 kPa by means of a modified recirculating still. The results obtained allow us to study the shape of the phase diagram of the system, to analyze the evolution with temperature of this equilibrium diagram and to show the differences with a similar system such as water + NaCl + 1-propanol. Moreover, the experimental data obtained have been compared with previously published data showing their important inconsistencies and presenting the rules that must be met by the experimental equilibrium data of water + non-volatile salt + organic solvent type systems in each one of the different SLLV, LLV and SLV equilibrium regions.The authors wish to thank the DGICYT of Spain for the financial support of project CTQ2014-59496

Ethanol dehydration via azeotropic distillation with gasoline fractions as entrainers: A pilot-scale study of the manufacture of an ethanol–hydrocarbon fuel blend

We establish experimentally and through simulations the economic and technical viability of dehydrating ethanol by means of azeotropic distillation, using a hydrocarbon as entrainer. The purpose of this is to manufacture a ready-to-use ethanol–hydrocarbon fuel blend. In order to demonstrate the feasibility of this proposition, we have tested an azeotropic water–ethanol feed mixture, using a hydrocarbon as entrainer, in a semi pilot-plant scale distillation column. Four different hydrocarbons (hexane, cyclohexane, isooctane, and toluene) that are representative of the hydrocarbons present in ordinary gasoline have been tested. Each of these hydrocarbons was tested separately in experiments under conditions of constant feed rate and variable reboiler heat duty. The experimentally obtained results are compared with results calculated by a simulator. Finally, the proposed and traditional ethanol dehydration processes are compared to ascertain the advantages of the former over the latter

Ethanol dehydration via azeotropic distillation with gasoline fraction mixtures as entrainers: A pilot-scale study with industrially produced bioethanol and naphta

Various hydrocarbons (n-hexane, cyclohexane, toluene, isooctane) and mixtures of them (binary, ternary or quaternary), as well as two different types of industrially produced naphtha (one obtained by direct distillation and the other from a catalytic cracking process), have been tested as candidate entrainers to dehydrate ethanol. The tests were carried out in an azeotropic distillation column on a semi pilot plant. The results show that it is possible to dehydrate bioethanol using naphtha as entrainer, obtaining as a result a fuel blend with negligible water content and ready for immediate use in motor vehicles