Preparation and Characterization of Gemini Surfactant Intermedium

This paper studies the preparation process and characterization of gemeni-diol, an intermedium compound for synthesizing anionic gemini surfactant. Firstly, as a material to synthesize anionic gemini surfactant, high purity ethylene glycol diglycidyl ether (EGDGE) is obtained by distill epoxy resin thinner at a reduced pressure. Based on gas chromatogram, 94.51 percent of liquid at cut points of 116-119℃/5mmHg is EGDGE. Then the effects of catalyst and reaction time on the reaction of nonylphenol and EGDGE are investigated. The results show the optimized conditions to synthesize gemini-diol are as following: using 0.25%KOH and 0.25% phosphorus triphenyl as catalyst to keep the reaction of nonylphenol and EGDGE at 110℃ for 3-5h. The yield of gemini-diol is 88.2% under these conditions

The Effect of Betaine Surfactant on Carbonate Reservoir Wettability in Self-Diverting Acidizing Stimulation

Contact angle alterations of carbonate cores after immersing in spent acid with oleyl amido propyl betaine surfactant were measured to clarify the effect of viscoelastic surfactant on the wettability of carbonate reservoir during self-diverting acidizing. The results showed that spent acid solutions with hydrochloric acid and betaine surfactant induced core wettability to water-wetting for initially oil-wet rocks, and oil-wetting for initially water-wet rocks. Longer immersion time and higher concentration of surfactant enhanced the effects. The adverse wettability reversal for water-wet reservoir was eliminated by mutual solvent or brine postflush. Chemical mechanisms of the wettability alteration were interpreted

Nitrogen Doped Carbon Nanosheets Encapsulated in situ Generated Sulfur Enable High Capacity and Superior Rate Cathode for Li-S Batteries

Lithium-sulfur batteries (LSBs), with large specific capacity (1,675 mAh g−1), are regarded as the most likely alternative to the traditional Lithium-ion batteries. However, the intrinsical insulation and dramatic volume change of sulfur, as well as serious shuttle effect of polysulfides hinder their practical implementation. Herein, we develop three-dimensional micron flowers assembled by nitrogen doped carbon (NC) nanosheets with sulfur encapsulated (S@NC-NSs) as a promising cathode for Li-S to overcome the forementioned obstacles. The in situ generated S layer adheres to the inner surface of the hollow and micro-porous NC shell with fruitful O/N containing groups endowing both efficient physical trapping and chemical anchoring of polysulfides. Meanwhile, such a novel carbon shell helps to bear dramatic volume change and provides a fast way for electron transfer during cycling. Consequently, the S@NC-NSs demonstrate a high capacity (1,238 mAh g−1 at 0.2 C; 1.0 C = 1,675 mA g−1), superior rate performance with a capacity retention of 57.8% when the current density increases 25 times from 0.2 to 5.0 C, as well as outstanding cycling performance with an ultralow capacity fading of only 0.064% after 200 cycles at a high current density of 5.0 C

Conversion of reverse osmosis membranes into metal-free carbocatalyst for electrochemical syngas production

Reverse osmosis (RO) membranes are widely employed in water treatment, raising needs for developing spent membrane modules waste management system. This study investigates the upcycling of spent RO membranes through a facile two-step process into functional carbocatalysts that can be successfully applied in electrochemical syngas production with tunable CO/H2 ratios. At first, the spent RO membrane module was pyrolyzed at 600 °C into char. The obtained char demonstrated poor electrochemical performance. Therefore, the char was further subjected to a high temperature (700–1000 °C) doping with melamine. The presence of melamine and the heat treatment were found crucial to convert the char into electrochemically active carbocatalysts. The prepared carbocatalysts showed an enhanced electrochemical reduction capability towards CO2 and H2O producing a mixture of CO and H2. The higher heat treatment temperature of the char increased the carbonization degree and the relative content of graphitic N groups. As a result, the carbocatalyst heat-treated at 1000 °C exhibited the highest CO selectivity with Faradaic efficiency up to 70.1%. Moreover, CO/H2 volumetric ratio of syngas could be easily regulated from 3:1 to 1:10 by adjusting applied electrochemical potentials. In this respect, the proposed two-step approach for the carbocatalyst synthesis could be a feasible strategy for addressing the RO membrane waste and producing syngas with suitable composition for a variety of industrial applications

A composite electrode of TiO2 nanotubes and nanoparticles synthesised by hydrothermal treatment for use in dye-sensitized solar cells

In dye-sensitized solar cells, highly ordered TiO2 nanotube arrays provide superior electron transport. However, their low surface area limits the amount of dye loading and thus the photocurrent. In the present work, a hydrothermal treatment of the TiO2 nanotubes was carried out to form TiO2 nanoparticles on the tube walls, thereby increasing the surface area for a higher amount of dye loading. The nanotube arrays were prepared by electrochemical anodization and subsequently hydrothermally treated in water at 90 °C. Using the same nanotube length (i.e., 6.5 μm), but different treatment durations, it was found that nanotubes under hydrothermal treatment for 45 min yielded the best photovoltaic performance, due to the combined merits of a high surface area and vectorial electron transport. Under the same treatment duration (i.e., 45 min), but using different nanotube lengths, nanoparticle formation was found to be accelerated in the longer tubes. The parts of the tubes near the bottom were constantly filled with nanoparticles, which limited cell efficiency to about 2.2% when the length was over 16.5 μm. Accordingly, a further efficiency enhancement of up to 3.5% was achieved with tubes of 16.5 μm by adjusting the duration of the hydrothermal treatment

Fabrication of PANI/C-TiO2 Composite Nanotube Arrays Electrode for Supercapacitor

Polyaniline/carbon doped TiO2 composite nanotube arrays (PANI/C-TiO2 NTAs) have been prepared successfully by electrodepositing PANI in C-TiO2 NTAs which were prepared by directly annealing the as-anodized TiO2 NTAs under Ar atmosphere. The organic residual in the TiO2 NTAs during the process of anodization acts as carbon source and is carbonized in Ar atmosphere to manufacture the C-TiO2 NTAs. The specific capacitance of the PANI/C-TiO2 electrode is 120.8 mF cm−2 at a current density of 0.1 mA cm−2 and remains 104.3 mF cm−2 at a current density of 2 mA cm−2 with the calculated rate performance of 86.3%. After 5000 times of charge-discharge cycling at a current density of 0.2 mA cm−2, the specific capacitance retains 88.7% compared to the first cycle. All these outstanding performances of the as-prepared PANI/C-TiO2 NTAs indicate it will be a promising electrode for supercapacitor