Preparation of Wheat Straw Hot-Pressed Board through Coupled Dilute Acid Pretreatment and Surface Modification.

The production of wheat straw waste board materials encounters challenges, including inadequate inherent adhesiveness and the utilization of environmentally harmful adhesives. Employing a hot-pressed method for converting wheat straw into board materials represents a positive stride towards the resourceful utilization of agricultural wastes. This study primarily focuses on examining the influence of hot-pressing process conditions on the mechanical properties of wheat straw board materials pretreated with dilute acid. Additionally, it assesses the necessity of dilute acid treatment and optimizes the hot-pressing conditions to achieve optimal results at 15 MPa, 2 h, and 160 °C. Furthermore, a comprehensive process is developed for preparing wheat straw hot-pressed board materials by combining dilute acid pretreatment with surface modification treatments, such as glutaraldehyde, citric acid, and rosin. Finally, a thorough characterization of the mechanical properties of the prepared board materials is conducted. The results indicate a substantial improvement in tensile strength across all modified wheat straw board materials compared to untreated ones. Notably, boards treated with glutaraldehyde exhibited the most significant enhancement, achieving a tensile strength of 463 kPa, bending strength of 833 kPa, and a water absorption rate of 14.14%. This study demonstrates that combining dilute acid pretreatment with surface modification treatments effectively enhances the performance of wheat straw board materials, offering a sustainable alternative to traditional wood-based board materials.

Surface-enhanced Raman scattering of flexible cotton fiber-Ag for rapid adsorption and detection of malachite green in fish.

The residual of malachite green (MG) in fish is one of the major food safety concerns for consumers. It is important to develop simple and instant analytical methods to identify MG residues in fish. We fabricated flexible cotton surface-enhanced Raman scattering substrate, which offers good flexibility, uniformity and excellent adsorption capability. The UV-vis DRS spectra, transmission electron microscopy and scanning electron elemental mapping images shown that the Ag NPs were closely packed on the surface of cotton fiber. The adsorption feature of cotton fiber could adsorb MG from solution and surface of fish. The Quick Easy Cheap Effective Rugged and Safe (QuEChERS) sample preparation method was used to adsorb MG in fish for SERS sensing. The limit of detection of MG in fish using this developed method was as low as 0.05 ppm. The QuEChERS-SERS analysis method exhibits the capability for multiplex detecting mixture of MG and Dimetridazole at different ratios (5 ppm, 1/400 and 1/4000) from fish. The results indicated that the cotton fiber-Ag composite was suitable employed as SERS substrate for simple and instant detecting trace contaminants in food.

Facile detection of carbendazim in food using TLC-SERS on diatomite thin layer chromatography.

This work aims to isolate and detect pesticide (carbendazim) residue in real food samples: orange juice and kale leaves. The combination of on-chip thin layer chromatography (TLC) and surface enhanced Raman scattering (SERS) spectroscopy was used for the separating and detecting of carbendazim (MBC) from the complex food sample. In order to achieve on-site detection of MBC from real food sample, the portable Raman spectrometer was coupled with TLC-SERS. The porous stationary phase composed of diatomite biosilica is beneficial for SERS enhancement and eluent migration. The experiments exhibited that the diatomite chip was suitable for TLC separation and has not shown SERS background and provided excellent separation efficiency, 10-8 M silver colloids were appropriate for the SERS measurement on TLC chip. The food sample was directly spotted onto the diatomite chip for TLC separation without any pretreatment. The separation and detection process were finished in less than 5 min, the mixture of pyrimethanil, pymetrozine and MBC could be distinguished simultaneously by TLC-SERS at one diatomite chip. The MBC in orange juice and kale were successfully detected, and a limit of detection (LOD) less than 2 ppm could be achieved.

Preparation of multi-functional magnetic-plasmonic nanocomposite for adsorption and detection of thiram using SERS.

Magnetic materials have been widely used for constructing substrate in surface enhanced Raman scattering (SERS) sensing due to the magnetic responsibility. Here, we reported a facile and effective approach to construct multi-functional SERS substrate based on assembling Ag nanoparticles (NPs) on porous Fe microspheres. The porous Fe microspheres were prepared through hydrogen reduction of Fe2O3 NPs with porous structure, in which the size and morphology of Fe could be well controlled. The surface of Fe was grafted with amino group, and then decorated with Ag NPs. The surface area and pore size of Fe microsphere were characterized by nitrogen adsorption and desorption. The Fe@Ag nanocomposite illustrated a good SERS activity. Furthermore, this substrate could be used for pesticide monitoring by portable Raman spectrometer. Especially, the porous Fe microsphere could adsorb analyte from target sample and the Fe@Ag could be concentrated by magnetic force to amplify the SERS signal for thiram detection.

A novel forced separation method for the preparation of paraffin with excellent phase changes.

A novel forced separation method based on driving force vacuum sweating was used to prepare high melting point paraffin with high phase-change enthalpies. The effects of the vacuum pressure and final separation temperature on the forced separation of the paraffin components were investigated. The research results showed that the optimal vacuum pressure for forced separation was 80.0 kPa. The performance of forced separation was improved with the increase in the final temperature. Increasing the final temperature increased the driving force of the separation of solid-state components and liquid components during sweating, which improved the product yield, shortened the production cycle, and reduced the oil content. The phase changes exhibited by the separation products were tested at 70 °C under optimal conditions. The raw materials and forced separation products were analyzed through Fourier transform infrared spectroscopy analysis (FT-IR), gas chromatography analysis (GC), differential scanning calorimetry analysis (DSC), and X-ray diffraction analysis (XRD). The results of these analyses showed that as the forced separation temperature was increased, the carbon atom number distribution range of the products narrowed, and the content of n-paraffin was drastically improved. The content of n-paraffin in the final fraction obtained through the forced separation of paraffin was 89.8% with a phase-transition temperature of 69.74 °C and a phase-transition enthalpy of 214.71 J g-1. A significant solid-solid phase transition peak was observed in the final fraction obtained through the forced separation of paraffin, which verified that paraffin was an excellent phase-change material for energy storage.

The ultrasound thermal cracking for the tar-sand bitumen.

The influence of ultrasonic irradiation on the tar-sand bitumen in the process of thermal cracking with an inert atmosphere was investigated thoroughly. The product distribution and coke characteristic produced by the conventional thermal cracking (CTC) and ultrasound thermal cracking (UTC) were invested at the following condition: ultrasound frequency 20 kHz, ultrasonic power 2000 W, reaction time 2 h, reaction temperature from 400 to 440 °C. The result of the liquid products distribution indicated that UTC can significantly increase gasoline yield and diesel yield, and dramatically reduce VGO (Vacuum Gas Oil) yield and residuum (greater than 500 °C) yield. The analysis of gas products showed that there were no significant differences for the gas distribution between the two reactions (methods), indicating that reaction of UTC still conformed to a radical chain mechanism, but the ratio of olefin/paraffin was greatly reduced in the process of UTC, which was attributed to the hydrogen transfer reaction promoted by ultrasound. The result of the analysis by SEM, FT-IR, Raman, XRD and Zeta potential demonstrated that there was a significant difference for the morphology of cokes produced by the two methods. Mesocarbon microbeads (MCMB) was discovered in the process of UTC, which should be due to that the polymerization of the free macro-radicals produced from PAHs (Polycyclic Aromatic Hydrocarbons) promoted by ultrasonic cavitation. In addition, it can be inferred that the viscosity of the second liquid phase was reduced by ultrasonic mechanical function through the breakage of the stack of asphaltene molecules cross-linked by van der Waals force. According to the mesophase theory, the ultrasound irradiation promoted the formation of the second liquid phase, extended its existence time and reduced its viscosity, resulting in the formation of MCMB controlled by the surface tension during the process of UTC.