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Due to the excellent broadcasting characteristics of radio signals, simultaneous wireless information and power transfer (SWIPT) can transmit both information and energy, and provide users with stable power supply. Wireless channel has the characteristics of openness, which will lead to the leakage of information in the SWIPT system. It is one of the research hotspots in the industry to ensure the secure transmission of information in SWIPT system where there are differences in the transmission of energy and information. This paper proposes an ‘information-energy’ dynamic switching opportunistic secure transmission scheme. First, a model considering three factors of multi-cell, multi-user and multiple eavesdropper is established which assumes that the user adopts a time-domain switching receiver that collects energy in a nonlinear model. Then, combined with the time-varying wireless channel, a dynamic information energy switching transmission scheme based on signal-to-interference noise ratio threshold is proposed. Finally, the energy and information transmission performance of the scheme are comprehensively analysed.

In many regions, even if waste vegetable oil is used as raw material, the profits of biodiesel (fatty acid methyl ester, FAME) enterprises still remain restricted, and they are facing environmental problems caused by the by‐product glycerol. Hence, value‐added utilization of FAME and glycerol is a promising alternative to improve the competitiveness of biodiesel enterprises in the economy and environmental protection. In this paper, FAME and glycerol were utilized to prepare epoxidized acyl glycerides by transesterification and epoxidation. In the transesterification, acyl glycerides were prepared by reacting FAME and glycerol catalyzed by K2CO3. The contents of monoacyl glyceride, diacyl glyceride, and triacyl glyceride in the acyl glycerides were about 50%, 40%, and 10%, and the optimal conditions were a temperature of 200°C and the molar ratio of FAME to glycerol of 1:1. In the epoxidation, selectivity of epoxides was significantly affected by monoacyl glyceride content, and a treatment method was developed to control the monoacyl glyceride content <5%. In addition, the plasticity of epoxidized acyl glycerides to partially substitute dioctyl phthalate in polyvinyl chloride was studied, the overall mechanical properties, thermal stability, and extraction resistance were improved. In this work, FAME and glycerol were utilized to prepare epoxidized acyl glycerides with higher value‐added, which provide a potential solution for improving the market competitiveness of biodiesel enterprises. [ABSTRACT FROM AUTHOR]

Oily sludge, as a critical hazardous waste, requires appropriate treatment for resource recovery and harmfulness reduction. Here, fast microwave-assisted pyrolysis (MAP) of oily sludge was conducted for oil removal and fuel production. The results indicated the priority of the fast MAP compared with the MAP under premixing mode, with the oil content in solid residues after pyrolysis reaching below 0.2%. The effects of pyrolysis temperature and time on product distribution and compositions were examined. In addition, pyrolysis kinetics can be well described using the Kissinger-Akahira-Sunose (KAS) and the Flynn-Wall-Ozawa (FWO) methods, with the activation energy being 169.7–319.1 kJ/mol in the feedstock conversional fraction range of 0.2–0.7. Subsequently, the pyrolysis residues were further treated by thermal plasma vitrification to immobilize the existing heavy metals. The amorphous phase and the glassy matrix were formed in the molten slags, resulting in bonding and, hence, immobilization of heavy metals. Operating parameters, including working current and melting time, were optimized to reduce the leaching concentrations of heavy metals, as well as to decrease their volatilization during vitrification. [ABSTRACT FROM AUTHOR]

A stable temperature site and the speed of heating the feedstocks play a key role in pyrolysis processes. In this study, the product distribution arising from pyrolysis of methyl ricinoleate (MR) at 550 °C with low and high heating rates was first studied by pyrolysis–gas chromatography/mass spectrometry (Py-GC/MS). The results show that fast pyrolysis of MR favored the production of undecylenic acid methyl ester (UAME) and heptanal (HEP). Density functional theory (DFT) calculations were employed to reveal the UAME and HEP formation process from pyrolysis of MR. The bond dissociation energies (BDEs) of C–C bonds in MR showed that the C11–C12 bond is the weakest. This suggests that UAME and HEP are two major products. The process of slow and fast MR pyrolysis was the dehydration-first and the pyrolysis-first trend, respectively. The calculated activation energies of MR pyrolysis to UAME and HEP and MR dehydration to 9,12-octadecadienoic acid methyl ester were 287.72 and 238.29 kJ/mol, respectively. The much higher product yields obtained in the fast pyrolysis reactors than those from conventional tubular reactors confirmed the proposed process. [ABSTRACT FROM AUTHOR]

Trimethylolpropane fatty acid triester (TFATE) is a promising biolubricant as an environmentally friendly substitute to conventional mineral-based lubricants. However, the issues of extensive energy consumption from vacuum maintenance and feedstock saponification caused by strong alkaline catalysts exist in current TFATE-based biolubricant synthesis. Here, sustainable production of biolubricant was achieved with methyl oleate (MO) from non-edible oil sources as the feedstock and moderate alkaline K 2 CO 3 as the catalyst. Nitrogen gas stripping method instead of vacuum was adopted for methanol removal. The effects of agitation speed, N 2 flow rate, catalyst amount, MO to trimethylolpropane (TMP) molar ratio and temperature on MO conversion and TFATE selectivity were examined. The TFATE selectivity reached 95.6% under the optimized conditions. Leaching tests indicated neglectable K 2 CO 3 dissolution in reaction products. The kinetic parameters for the three consecutive transesterification reactions were calculated. In addition, the synthesized biolubricants exhibit low acid value and volatility, moderate iodine value, superior thermal stability, and good rheological and frictional properties. [Display omitted] • Biolubricant TFATE was produced by methyl oleate transesterification over K 2 CO 3 catalyst. • Nitrogen gas stripping method instead of vacuum was adopted for methanol removal. • The TFATE selectivity reached 95.6% under the optimized conditions. • Kinetic parameters for three consecutive transesterification reactions were calculated. • Products show superior thermal stability and good rheological and frictional properties. [ABSTRACT FROM AUTHOR]