Dynamic experimental study of a new electrocoagulation apparatus with settlement scheme for the removal process in oilfield

Multispectroscopic and computational techniques to study the interaction of anthraquinone appended sensor with calf thymus DNA

An anthraquinone based derivative (AQ) has been designed and synthesized to find its applications for the interactions with calf thymus DNA (ctDNA) involving various spectroscopic techniques, thermodynamic and computational approaches. The UV-vis studies pointed to interaction of AQ with ctDNA via groove binding mode, which has been further supported well by the ionic strength studies, viscosity measurement, circular dichroism and melting temperature (Tm) curves. These findings have been further validated by dye-displacement assay and molecular docking studies. The analysis of thermodynamic parameters supports that the AQ-ctDNA binding is entropy favoured and enthalpy disfavoured and main acting binding interaction is hydrophobic interaction. The outcomes of the molecular modelling suggested that AQ might have entered the A-T abundant area of the ctDNA.Communicated by Ramaswamy H. Sarma.

Tangential effluent inlet in a cylindrical electrocoagulation reactor containing curved electrodes, and its use in crude oil in water treatment

A continuous electrocoagulation reactor, with curved electrodes, polarity switch, and cylindrical geometry, was used for emulsified crude oil in water separation. Apparatus novelty consists of an inlet arranged to promote a circular flow regime. The effects of flow rate (2 and 6 mL.s^-1), electrical current (2 and 4 A), and distance between electrodes (1.5 and 2.5 cm) were investigated using a full factorial design and statistical analysis. Using 6 mL.s^-1 flow rate, 2 A electric current and 2.5 cm electrode distance; 86% oil removal was obtained at a pH < 9.0. For this configuration, the system will process 21.6 L of oily emulsion while consuming 6.92 Wh. Oil removal increased with flow rate, a novel characteristic created by the unusual geometry of the system.

Recent advantages in electrochemical monitoring for the analysis of amaranth and carminic acid food colors

This study provides a comprehensive review of the latest developments in the electrochemical impressions of the important dyestuffs including amaranth and carminic acid. Food colors are organic substances that have important effects on human health and food safety. While these substances do not pose a problem when used in the daily intake (ADI) amounts, they harm human health when consumed excessively. Amaranth and carminic acid are synthetic and natural food colors ingredients, respectively. Analysis of these substances in food, pharmaceutical, cosmetic and textile samples is extremely important because of their genotoxicity, cytostatic and cytotoxic effects. Electroanalytical methods, which have great advantages over traditional analytical methods, shed light on the scientific world. Electrochemical monitoring modules, which are fast, simple, accurate, reliable, and highly selective, are promising for the determination of both substances. Until now, amaranth and carminic acid food determinations have been carried out successfully with electrochemical monitoring techniques in many numbers in the literature. Voltammetric techniques are the most widely used among these electroanalytical methods. In particular, square wave and differential pulse voltammetric techniques, which have extraordinary properties, have been heavily preferred. Limits of detection (LOD) comparable to the standard analytical method have been achieved using these methods, which have very quick analysis durations, high precision and accuracy, do not require long preprocessing, and have great selectivity. In addition, more sensitive and selective analyses of amaranth and carminic acid in natural samples were carried out with numerous indicator electrodes. The merits of powerful electrochemical monitoring studies for the determination of both food colors during the last decade are presented in this study. Moreover, parameters such as analytical applications, detection limits, electrochemical methods, selectivity, working electrodes, and working ranges are summarized in detail.

Extraordinary Superhydrophobic Polycaprolactone-Based Composite Membrane with an Alternated Micro-Nano Hierarchical Structure as an Eco-friendly Oil/Water Separator

Extraordinary superhydrophobic polycaprolactone (PCL) composite membranes with an alternated hierarchical micro-nano structure were designed by addition of SiO₂ aerogel. The highest water contact angle (WCA) of 166.8 ± 1.5° was obtained when SiO₂ aerogel content was 0.5% (PCL/SiO₂-a0.5) in the PCL composite membrane, which was higher than other reported polymer-based membranes. SiO₂ aerogel lowered PCL composite membrane's surface energy. The triple curvature structure composed of microspheres, nanospheres, and nanofibers produced on PCL/SiO₂-a0.5 membranes endowed the excellent roughness of the surface. Also, the inner structure of the PCL/SiO₂-a0.5 composite membrane composed of micro-nano spheres, nanofibers, and microfibers increased the porosity of the separation membrane, which would provide more adsorption space. The PCL/SiO₂-a0.5 composite membrane as a separator for surfactant-stabilized emulsions of water-in-oil showed ultrahigh separation flux and efficiency. Meanwhile, the PCL/SiO₂-a0.5 composite membrane had an outstanding chemical resistance, self-cleaning ability, and good reusability. The composite membranes reported in this work as eco-friendly separation materials possessed all these characters in oil/water separation. This research proposed a very simple method to design eco-friendly high-efficiency separators through the construction of the alternated micro-nano hierarchical structure.

Quantitative contribution study and comparison between electrocoagulation, anode-electrocoagulation and chemical coagulation using polymer-flooding sewage

This work aimed to quantify the contribution of electrocoagulation(EC) mechanisms on emulsified oil removal from polymer-flooding sewage (PFS), and also to quantitatively compare the performance of EC, anode-electrocoagulation(AEC) and chemical coagulation(CC) on PFS treatment. An apparatus which introduced the salt bridge was proposed to help separate the anode and cathode. To quantify the contribution of coagulation and oxidation individually, the EDTA, a chemical addictive which can inhibit the ability of Al³⁺ was added to shield the effect of coagulation. The experimental results show that in the PFS treatment by EC method, about 80% of emulsified oil in anode zone was removed by coagulation while only 11%-13% was oxidized; In cathode zone, about 13%-14% of the oil was removed by flotation. Besides, the results suggest that the separation of anode and cathode not only result in the low demulsification efficiency but also generated the fragile flocs. During the comparison and contrast of purification performance of EC, AEC and CC, the effects of treatment time and current densities(aluminum doses) on oil removal was investigated, the pH and absorption spectra evolution over time were also analyzed. The results showed that under all conditions studied, the EC performance outperforms AEC and far beyond CC.

Experimental study on the transport characteristics of buried pipeline leakage and the performance of groundwater remediation system

Enhanced understanding of light non-aqueous phase liquid (LNAPL) infiltration into sandy porous medium is significant to the effective design of remediation strategies. A system for buried pipeline leakage in 2-D sandbox was conducted to investigate the migration of diesel through a sandy porous medium, and the system could also be conducted to investigate groundwater remediation. Two groups of experiments were carried out. The first experiment consisted of diesel infiltration into a fine sand matrix. We could notice that diesel spilled in dry sand layer at a constant speed and the diesel front kept longitudinal movement due to the gravity before it arrived at the edge of the capillary zone. The diesel front broadened as a whole because of the capillary force jacking after it reached the capillary zone. Finally, the bulk of the diesel was contained on top of the capillary zone. To protect groundwater, the second experiment consisted of remediating soils and groundwater. The results indicated that the voltage of electrocoagulation apparatus had a great influence on the treatment effect, and the removal rate of diesel was found to be more than 90% with a constant voltage of 20 V. The efficiency of groundwater remediation was influenced by the flow velocity, and it took 11 h when the flow velocity was 2.089 L/min. To summarize, the research was conducive to the study on diesel pollution control and pollution prediction.