Construction of photocatalytic membrane separation materials and its research progress in wastewater treatment

Membrane separation has been widely used in the field of water treatment due to its characteristics such as operation at room temperature, high separation efficiency and environmental friendliness. However, membrane pollution caused by suspended substances or soluble substances in the feed solution limits the further development of membrane technology. Photocatalytic membrane can use photocatalyst to degrade the pollutants on the membrane efficiently and improve the separation efficiency and anti-pollution performance of the membrane. This paper firstly introduced the types of photocatalysts used for the preparation of photocatalytic membrane, including metal oxides, graphite phase carbon nitride, bismuth-based materials and new two-dimensional materials. Then the construction methods of photocatalytic membranes with self-cleaning ability (surface modification and matrix blending of membrane) were reviewed, and the pollutant removal mechanism of photocatalytic membrane was summarized. The application scenarios of photocatalytic membrane for dyes, antibiotics, emerging pollutants in wastewater treatment of different industries were listed. Finally, the article gave an outlook on its future development and provided a certain reference for the development of highly anti-pollution membrane materials

The Control Method of Twin Delayed Deep Deterministic Policy Gradient with Rebirth Mechanism to Multi-DOF Manipulator

As a research hotspot in the field of artificial intelligence, the application of deep reinforcement learning to the learning of the motion ability of a manipulator can help to improve the learning of the motion ability of a manipulator without a kinematic model. To suppress the overestimation bias of values in Deep Deterministic Policy Gradient (DDPG) networks, the Twin Delayed Deep Deterministic Policy Gradient (TD3) was proposed. This paper further suppresses the overestimation bias of values for multi-degree of freedom (DOF) manipulator learning based on deep reinforcement learning. Twin Delayed Deep Deterministic Policy Gradient with Rebirth Mechanism (RTD3) was proposed. The experimental results show that RTD3 applied to multi degree freedom manipulators is in place, with an improved learning ability by 29.15% on the basis of TD3. In this paper, a step-by-step reward function is proposed specifically for the learning and innovation of the multi degree of freedom manipulator’s motion ability. The view of continuous decision-making and process problem is used to guide the learning of the manipulator, and the learning efficiency is improved by optimizing the playback of experience. In order to measure the point-to-point position motion ability of a manipulator, a new evaluation index based on the characteristics of the continuous decision process problem, energy efficiency distance, is presented in this paper, which can evaluate the learning quality of the manipulator motion ability by a more comprehensive and fair evaluation algorithm.</jats:p

Two-dimensional Na-Bentonite@MXene composite membrane with switchable wettability for selective oil/water separation

MXene-based two-dimensional (2D) material membranes have attracted an increasing number of attentions in the field of separation and purification. However, the easily oil-pollution of MXene membrane still limit its further application for oil/water separation. In this work, Na-Bentonite was embedded into MXene nanosheets and then a series of Na-Bentonite@MXene (NBM) composite membranes were prepared by one-step hydro -thermal pretreatment and vacuum self-assembly on polyvinylidene fluoride membrane surface. The modified composite membranes exhibited excellent separation performances with a rejection ratio above 96 % and a flux recovery rate (FRR) higher than 86 % after 8 cycling tests for oil/water emulsion. In addition, the sandwich structure consisting of MXene nanosheets and Na-Bentonite could not only play a positive role in the stability of composite membrane, but also formed a special micro-nano structure on membrane surface, resulting in a switchable wettability of composite membrane. When the membrane surface was pretreated with water or oil, it presented hydrophilic/hydrophobic or hydrophobic/oleophilic surfaces, respectively, which realized the effec-tive separation for different components in oil/water emulsion. This work provides a new method for the design and construction of MXene-based 2D membrane with continuous anti-fouling capacity, which shows a great application potential in the treatment of oily wastewater

Two-dimensional Na-Bentonite@MXene composite membrane with switchable wettability for selective oil/water separation

MXene-based two-dimensional (2D) material membranes have attracted an increasing number of attentions in the field of separation and purification. However, the easily oil-pollution of MXene membrane still limit its further application for oil/water separation. In this work, Na-Bentonite was embedded into MXene nanosheets and then a series of Na-Bentonite@MXene (NBM) composite membranes were prepared by one-step hydro -thermal pretreatment and vacuum self-assembly on polyvinylidene fluoride membrane surface. The modified composite membranes exhibited excellent separation performances with a rejection ratio above 96 % and a flux recovery rate (FRR) higher than 86 % after 8 cycling tests for oil/water emulsion. In addition, the sandwich structure consisting of MXene nanosheets and Na-Bentonite could not only play a positive role in the stability of composite membrane, but also formed a special micro-nano structure on membrane surface, resulting in a switchable wettability of composite membrane. When the membrane surface was pretreated with water or oil, it presented hydrophilic/hydrophobic or hydrophobic/oleophilic surfaces, respectively, which realized the effec-tive separation for different components in oil/water emulsion. This work provides a new method for the design and construction of MXene-based 2D membrane with continuous anti-fouling capacity, which shows a great application potential in the treatment of oily wastewater