Cooperative physical separation of oil and suspended solids from methanol-to-olefin wastewater: A pilot study.

Methanol-to-olefin (MTO) is an important non-petroleum chemical process for the preparation of light olefins. However, the MTO process consumes copious amounts of water and produces large amounts of untreated effluent. Therefore, the realization of efficient wastewater treatment and recycling is key to the green low-carbon development of MTO. Here, a cooperative process combining swirl regenerating micro-channel separation (SRMS) and combined fibrous coalescence (CFC) technologies was proposed to separate high contents of oil and suspended matter in MTO wastewater. Using a pilot device with a treatment capacity of 1 m3/h, the average oil content in MTO wastewater decreased from 750 mg/L to <30 mg/L, while the average content of suspended matter decreased from 108 mg/L to <15 mg/L. Compared with a commercial MTO wastewater treatment process (olefin production capacity of 0.6 million tons per annum), the proposed method could reduce wastewater discharges and costs by 57% and US$ 0.23 million per annum respectively. Equipment costs and operational energy consumption were also reduced by 30% and >95% respectively. The combined process may provide the basis for the green and sustainable treatment of MTO wastewater and its recycling.

Nondestructive testing of runny salted egg yolk based on improved ConvNeXt-T.

Salted egg yolks from salted duck eggs are widely utilized in the domestic and international food industry as both raw materials and ingredients. When salted egg yolks are not fully cured and matured, they exist in a fluid state, with a mixture of solid and liquid internally. Due to this composition, they are susceptible to deterioration during storage and usage, necessitating their detection and classification. In this study, a dataset specifically for salted egg yolks was established, and the ConvNeXt-T model, employed as the benchmark model, underwent two notable improvements. First, a lightweight location-aware circular convolution (ParC) was introduced, utilizing a ParC-block to replace a portion of the original ConvNeXt-T block. This enhancement aimed to overcome the limitations of convolution in extracting global feature information while integrating the global sensing capability of vision transformer and the localization capability of convolution. Additionally, the activation function was modified through substitution. These improvements resulted in the final model. Experimental results indicate that the enhanced model exhibits faster convergence on the custom salted egg yolk dataset compared to the baseline model. Furthermore, a significant reduction of model parameters by a factor of 4 led to a 2.167 percentage point improvement in the accuracy of the test set. The ParC-ConvNeXt-SMU-T model achieved an accuracy of 96.833% with 26.8 million parameters. Notably, the improved model demonstrates exceptional effectiveness in recognizing salted egg yolks. PRACTICAL APPLICATION: This study can be widely applied in the process of salted egg yolk production and quality inspection, which can improve the actual sorting efficiency of salted egg yolks and reduce the labor cost at the same time. It can also be used for nondestructive testing of salted egg yolks by governmental enterprises and other regulatory authorities.

Removal of coke powders in coking wastewater using a hydrocyclone optimized by n-value.

Coke powders in the coking wastewater generated by petroleum refining industry needs to be removed to achieve water reuse for lack of water resources. This study developed a decoking hydrocyclone in the closed coking wastewater circulation treatment system to remove coke powders, which was highly efficient and environmentally friendly. Computational Fluid Dynamics (CFD) method was carried out to study the tangential velocity distribution index n-value to guide design of decoking hydrocyclone and experiment was conducted to verify the coke powders removal effect. It was found that the increase of n-value is conducive to the improvement of coke powders separation efficiency. A decoking hydrocyclone with a cone angle of 15° and an inlet size of 4 × 6 mm is the optimum hydrocyclone and the recovery efficiency of coke powders is stable at more than 90%. It is the first time for hydrocyclone successfully applied to the removal of coke powders in coking wastewater in the decoking process of petroleum refining industry, in which the separation efficiency of coke powders is considerably improved.

In situ analysis of dynamic laminar flow extraction using surface-enhanced Raman spectroscopy.

In this study, we performed micro-scale dynamic laminar flow extraction and site-specific in situ chloride concentration measurements. Surface-enhanced Raman spectroscopy was utilized to investigate the diffusion process of chloride ions from an oil phase to a water phase under laminar flow. In contrast to common logic, we used SERS intensity gradients of Rhodamine 6G to quantitatively calculate the concentration of chloride ions at specific positions on a microfluidic chip. By varying the fluid flow rates, we achieved different extraction times and therefore different chloride concentrations at specific positions along the microchannel. SERS spectra from the water phase were recorded at these different positions, and the spatial distribution of the SERS signals was used to map the degree of nanoparticle aggregation. The concentration of chloride ions in the channel could therefore be obtained. We conclude that this method can be used to explore the extraction behaviour and efficiency of some ions or molecules that enhance the SERS intensity in water or oil by inducing nanoparticle aggregation.