Copper sulfide anchored MXene improving photo-responsive self-healing polyurethane with enhanced mechanical and antibacterial properties.

Diseases caused by bacterial infection are becoming a major threat to human health. Therefore, developing efficient antibacterial materials is of great significance in improving medical care and protecting people's health. In this work, an accordion-like structural Ti3C2@CuS was synthesized by copper sulfide (CuS) nanospheres anchored firmly on the surface of Ti3C2Tx via the hydrothermal method. The multilayer Ti3C2@CuS becomes few-layered nanosheets after ultrasonic treatment, which have an enjoyable dispersion in the polyurethane (PU) matrix. PU and the released Cu2+ from Ti3C2@CuS are firmly linked by a coordination bond, which improves the mechanical properties and thermal stability of Ti3C2@CuS-PU and reduces the heavy metal ion pollution by blocking the Cu2+ released by forming coordination bonds. Moreover, Ti3C2@CuS-PU exhibits an excellent self-healing performance after 30 tensile cycles. Additionally, Ti3C2Tx and CuS could improve the separation efficiency of the electron-hole pairs of CuS to produce more reactive oxygen species (ROS) to kill bacteria. Ti3C2@CuS-PU maintains a highly long-term sterilization ability of more than 90 % in 30 days because of the synergistic effect of the sustained release of copper ions, the elevated ROS production ability, and the excellent dispersion of Ti3C2@CuS in PU. This work demonstrates a simple and promising route for designing multifunctional antibacterial self-healing materials.

Electrospun nanofiber composite membranes for geothermal brine treatment with lithium enrichment via membrane distillation.

In this study, a composite electrospun nanofiber membrane was fabricated and used to treat a geothermal brine source with lithium enrichment. An in-situ growth technique was applied to incorporate silica nanoparticles on the surface of nanofibers with (3-Aminopropyl) triethoxysilane as the nucleation site. The fabricated composite nanofiber membrane was heat pressed to enhance the integration of the membrane and its mechanical stability. The fabricated membranes were tested to evaluate their performance in feedwater containing different concentrations of NaCl in the range of 0-100 g/L, and the wetting resistivity of the membranes was examined. Finally, the optimal membrane was applied to treat the simulated geothermal brine. The experimental results revealed that the in-situ growth of nanoparticles and coating of flourosilane agent dramatically improved the separation performance of the membrane with high salt rejection, and adequate flux was achieved. The heat-pressed membrane obtained >99% salt rejection and flux of 14-19 L/m2h at varying feedwater salinity (0-100 g/L), and the concentration of the Li during the 24 h test reached >1100 ppm from the initial 360 ppm. Evaluation of the energy efficiency of the membranes showed that the heat-pressed membrane obtained the optimum energy efficiency in the high concentration of salts. Additionally, the economic analysis indicated that MD could achieve a levelized cost of 2.9 USD/m3 of lithium brine concentration as the heat source is within the feed. Overall, this technology would represent a viable alternative to the solar pond to concentrate Li brine, enabling a compact, efficient, and continuous operating system.

Development of a mobile groundwater desalination system for communities in rural India.

The consumption of saline groundwater has contributed to a growing incidence of renal diseases, particularly in coastal communities of India. Although reverse osmosis (RO) is routinely used to remove salt from groundwater, conventional RO systems (i.e. centralized systems using spiral wound RO elements) have limited utility in these communities due to high capital and maintenances costs, and lack of infrastructure to distribute the water. Consequently, there is a need to develop an appropriate solution for groundwater treatment based on small-scale, mobile and community-led systems. In this work, we designed a mobile desalination system to provide a simple platform for water treatment and delivery of goods to rural communities. The system employs tubular RO membranes packed in a single, low-profile vessel which fits below the cargo space. The low-profile enables minimal intrusion on the space available for the transportation of goods. Pressure is delivered by a belt driven clutch pump, powered by the engine. Water is treated locally by connecting the intake to the village well while the vehicle idles. A combined numerical and experimental approach was used to optimise the module/system design, resulting in ∼20% permeate flux enhancement. Experimental results revealed that the system can produce 16 L per square meter of membrane area per hour (LMH) at a salinity level of 80 ppm from a ∼2000 ppm groundwater when it is feed at 1 m3/h at 8 bars. This indicates that a vehicle equipped with 12 m2 of tubular RO membranes can deliver 1 m3 of drinkable water by using ∼0.9 L of diesel. Assuming eight such systems could be implemented in a community to fulfil the water demands for a village with 2000 residents, a social business study revealed that a payback time of 2.5 years is achievable, even if the sale price of the water is relatively low, USD 0.18 (Rs 12, which is half of the lowest market price) per 20 L, including providing a goods transportation service at price of USD 5.25 (Rs 350) per 100 km.