Lixin Xue

A post-treatment strategy, involving immersion in sodium hypochlorite solution, was developed, specifically effective in improving the reverse osmosis (RO) performance of polyethylene (PE) based thin film composite (TFC) polyamide (PA) membranes prepared from reverse phase interface polymerization (RIP) processes. RIP processes produced abundant amine groups on the PA surfaces to allow the formation of abundant PA~N(H)Cl intermediate, while the inertness of the PE substrates preserved PA~N(H)Cl for their self-coupling into azo linkages, -N=N-. The salt rejection rates of PA layers were improved due to the formation of azo cross-linkages, while the water permeation was improved from increases in surface area, pore volume, and surface ionic groups. After optimizing the concentration of NaClO solution, pH, and treating time, the permeance of PA/PE TFC membrane could be increased from 1.59 ± 0.02 Lm-2h-1·bar-1 to 1.63 ± 0.03 Lm-2h-1·bar-1, while the salt rejection rate was improved from 98.64 ± 0.06 % to 99.25 ± 0.08 %, retaining good operational stability, anti-pollution ability, and improved alkaline stability.

Polyamide (PA) based thin‐film nanocomposite (TFN) membranes containing zeolitic imidazolate framework (ZIF) particles, denoted as PA (ZIF)‐TFN membranes, were fabricated via interfacial polymerization (IP) between m‐phenylenediamine (MPD) and 1,3,5‐benzenetricarbonyl chloride (TMC). ZIF‐8 particles were incorporated by direct dispersion into the oil‐phase solution. Subsequently, the membranes were etched with xylenol orange disodium salt (XO) under acidic conditions to produce reverse osmosis (RO) membranes with improved water flux and salt rejection. These improvements were attributed to additional water‐permeation channels and the sealing of non‐selective interface defects. Solution pH, etching duration, and XO concentration also play roles in the structure and performance of the optimized RO membranes. After 12 h of etching, superior TFN/XO (12) RO membranes were obtained with rejection rate increased from (99.0% ± 0.2%) to (99.7% ± 0.1%), and water flux increased from (42.3 ± 0.9 L·m⁻²·h⁻¹) to (65.1 ± 0.9 L·m⁻²·h⁻¹). In addition, the membranes exhibited excellent boron removal rate, operational stability, and anti‐pollution performance under conditions of 32,000 ppm NaCl and 55 bar.

Developing heatable adsorbents for onsite monitoring and cleanup of viscous oil spills is a crucial but challenging task. Here, the preparation of a super‐hydrophobic heatable absorbent from polypropylene spun‐bound non‐woven fabrics (NWFs) made of fibers with shaped cross‐sections and coated with polypyrrole (PPy) and MXene (H‐MXene/PPy/PEG/PP) is presented. Their structures, heat absorption and dissipation under various heating modes are characterized, and their performance as heatable adsorbents for onsite monitoring and continuous removal of viscous crude oil spills is studied. The impacts of fiber cross sectional shapes, heating mode and operating conditions on the absorbent surface temperature, surface heat dissipating index and capacity, oil monitoring response time (RT), as well as oil absorption capacity and separation efficiency are systematically studied. Shaped cross sectional fibers shows faster oil absorption speed, resulted in shorter RT, faster oil recovery rates and lower surface heating capacity without changing the heat dissipating index. Photo‐heating coupled with Joule heating induces non‐Newtonian irradiative cooling, resulting in an unusually high heat dissipation index of 1.66–2.77. The RT at 1 sun irradiation intensity or 10 voltage is only 54 or 80 s, respectively. Under 1 kW/m ² , the continuous crude oil recovery rate reaches 176.5 kg·m ⁻² ·h ⁻¹ .

A cross substrate counter diffusion (CSCD) process between the solutions of Zn(II) solution and 2-methyl imidazole (2-MIM)-ammonia solution (pH = 10) to in situ grow ZIF-8 particles was developed to enhance the performance of polyamide (PA)/polyethylene(PE) based thin film composite (TFC) total heat exchange membranes (THEMs). In situ grown ZIF particles from CSCD processes had effectively blocked CO2 leakages across the PA separating layer by sealing the defect points, and provided selective water vapor permeating channels and surface area to enhance energy recovery efficiencies. The effects of Zn(II) loading concentration, CSCD reaction time and ligand type on the structure, CO2 barrier property and heat exchange efficiencies were systematically investigated. Under optimized conditions, sealing with ZIF-8 particles could decrease the CO2 permeance from 7.5 GPU to 1.15 GPU, at the same time, increase the sensible heat, latent heat and heat exchange efficiencies from 80 %, 53 %, 68 % to 96 %, 73 % and 82 % respectively.