Vanadium removal is a critical step in refining crude TiCl4 for titanium metallurgy. Low-valent titanium chloride (LTC) — a mTiCl3·AlCl3 solid solution (m = 1–3) prepared by AlCl3-assisted aluminothermic reduction of TiCl4 — is a promising reagent, yet how the AlCl3 content governs its structure and vanadium-removal activity remains unclear. Here we show that LTC composition dictates both the solid-solution speciation and VOCl3 reduction efficiency. The optimal LTC, prepared at 120 °C with 1.5 wt% AlCl3, contains 10.03 wt% TiCl3 and reduces VOCl3 in crude TiCl4 from 0.1481 to 0.0001 wt% at 0.7 wt% dosage and 136 °C for 30 min. Density functional theory calculations revealed that 3TiCl3·AlCl3 is the dominant active phase, adsorbing VOCl3 spontaneously (ΔGads = −12.7 kcal mol−1) and reducing it via a near-barrierless Cl-transfer pathway, whereas 2TiCl3·AlCl3 and TiCl3·AlCl3 bind VOCl3 endergonically and are essentially unreactive. Excess AlCl3 (>2.0 wt%) shifts the solid solution toward these less reactive compositions, degrading vanadium removal and increasing AlCl3 carryover. These findings establish a quantitative composition–structure–activity relationship for LTC and provide a rational basis for optimizing industrial TiCl4 refining.
Evaporative cooling precipitation (ECP) was applied for protein capture from cell culture medium. In ECP, the crude biological material is contacted with an ambient air stream while gently stirred in a rotating drum. Gradual evaporation of water causes cooling and concentration of the solution, and mitigates the formation of strong concentration gradients. The evaporation rate is correlated with the air parameters through underlying thermodynamic and kinetic dependences.Two different biological materials were used for the method verification: E. coli-derived recombinant Protein A that was precipitated from ammonium sulfate solutions at pH 5, and a CHO-derived monoclonal antibody (mAb) precipitated from polyethylene glycol solutions (3.35 kDa PEG) at pH 8. Compared to the conventional precipitation method, precipitant consumption in ECP reduced by 3 times while processing Protein A, and 2.4 times while processing mAb. This was achieved at a very low energy consumption. The process was tested at 20 and 40 mL scales in the drums of 5 and 10 cm length, respectively. The drums were operated at rotation velocity 25 or 50 rpm and at air flowrate 0.75–1.7 L s−1.The ECP precipitate of Protein A was dissolved in IMAC binding buffer and directly processed by IMAC, whose throughput was optimized using a mechanistic model. The coupling of ECP-IMAC under optimized conditions provided Protein A solutions with 95% chromatographic purity and a yield of 84% with a two-fold increase in throughput and a three-fold reduction in buffer consumption compared to the standalone IMAC purification. HCP, DNA, and endotoxins were removed from the row material at the level of LRV = 2, and the aggregate content was reduced by 93%. The purity of the mAb extracted from the ECP precipitate at pH 5 reached 99%, with an 80% yield. The DNA and HCP content was reduced to levels of LRV = 2.8 and 3.5, respectively, and the aggregate content was reduced below the detection limit.
Commercial polyamide (PA) nanofiltration (NF) membranes are widely used in advanced water treatment, but the properties of their preformed selective layers are difficult to tailor to specific separation requirements. Here, commercial NF270 membranes were reconstructed by isopropanol (IPA)-assisted swelling followed by acidic H2O2 oxidation. HCl treatment induced only minor changes, whereas H2O2 oxidation and IPA swelling promoted PA-network decrosslinking, chain relaxation, and redistribution of surface functional groups. Sequential IPA-H2O2 treatment produced the most pronounced reconstruction, increasing the surface O/N ratio from 1.18 to 1.27 and decreasing the crosslinking degree from 75.3% to 63.5%. The reconstructed selective layer became more negatively charged and hydrophilic and developed larger transport nanochannels, as reflected by a shift in zeta potential from −38 to −63 mV, a decrease in water contact angle from 53.5° to 30.0°, and increases in the molecular weight cutoff and average pore size to 675 Da and 0.66 nm, respectively. Water permeance increased from 15.6 to 25.6 L·m−2·h−1·bar−1, while high sulfate rejection was largely retained. During natural surface-water filtration, the optimized membrane effectively removed humic- and fulvic-like fluorescent dissolved organic matter while allowing partial passage of mineral ions. These results demonstrate the potential of IPA-assisted oxidation to convert commercial PA membranes toward loose-NF behavior for selective surface-water purification.
The nuclear fuel cycle produces uranium-containing wastewater, posing environmental risks. Photocatalysis can convert soluble U(VI) to insoluble species, but existing photocatalysts face a trade-off between high surface area and efficient charge separation. Herein, we adopt an arm-number-regulated pore engineering strategy: four-arm planar TPDA and three-arm trigonal pyramidal TAPA are copolymerized with naphthalene diimide (NDI) to yield two NDI-based conjugated porous polymers (PNDI-TPDA and PNDI-TAPA) with distinct pore structures. The four-arm system shows only single-sized micropores, while the three-arm system exhibits a bimodal distribution (primary and secondary pores). Both primary pores match dehydrated uranyl ions, but PNDI-TAPA's secondary pores also accommodate hydrated uranyl ions. The difference in uranyl species accommodation between the two materials endows PNDI-TAPA with a unique pore size advantage, enabling it to simultaneously achieve stronger visible-light absorption and superior charge separation and transport performance, which allows PNDI-TAPA to remove 99% of U(VI) within 3 h under a 300 W CEL-HXF300-T3 xenon lamp equipped with a 400 nm cutoff filter, with a rate constant 1.6 times that of PNDI-TPDA, along with good ionic tolerance and recyclability. Mechanistically, matched pores improve adsorption selectivity and enrichment via confinement; photogenerated electrons and superoxide radicals generate H2O2, which precipitates U(VI). This work identifies arm number as a useful molecular tool for tuning pore size in conjugated porous polymers, offering a new route to efficient photocatalysts for uranium extraction.
Under global carbon neutrality, zeolites are excellent CO2 adsorbents but limited by high feedstock costs. Coal gasification fine slag (CGFS) offers a promising low-cost alternative feedstock. In this study, the ash-rich component of CGFS, pretreated by flotation decarbonization and acid leaching for impurity removal, was used as the raw material to synthesize ZSM-5 zeolite in situ via a microwave-assisted method. The synthesis process was systematically optimized, the formation mechanism was elucidated, and the CO2 adsorption performance was evaluated. The results show that under the conditions of aging at 60 °C for 6 h, and crystallization at 180 °C for 4 h with a heating rate of 1 °C/min under a microwave power of 1000 W, ZSM-5 zeolite with a specific surface area of 243.34 m2/g and a pore volume of 0.38 cm3/g can be prepared, with the synthesis cycle significantly shortened compared with traditional methods. The product possesses a hierarchical pore structure dominated by micropores, and its formation follows a sol-gel self-assembly process. Aluminum mainly exists in the framework in tetrahedral coordination, while impurities such as iron and titanium are primarily present as extra-framework hexacoordinated metal clusters and partially substitute for framework aluminum, providing active sites for CO2 adsorption. At room temperature, its CO2 adsorption capacity reaches 1.64 mmol/g, accompanied by favorable adsorption stability and CO2/N2 selectivity. The adsorption process conforms to the Sips isotherm model and is a spontaneous, exothermic and entropy-decreasing process. This study provides a new direction for the high-value utilization of CGFS and the development of low-cost CO2 adsorbents.
