Synergistic removal of U(VI) from aqueous solution by TAC material: Adsorption behavior and mechanism.

The adsorption and recovery of uranium from wastewater is of positive significance to the development of nuclear industry and environmental remediation. The ternary polymer (PZS-co-TA) was prepared from hexachlorocyclotriphosphazene (HCCP), 4,4-sulfonyldiphenol (BPS) and tannic acid (TA) under ultrasonic. TAC was then obtained after carbonization under high temperature from PZS-co-TA. The structure and performance of TAC were analyzed using SEM, EDS, FT-IR, XRD, Raman, BET and TG. The adsorption capacity of TAC for uranium under different static adsorption conditions was investigated. The adsorption process was more consistent with pseudo-second-order model. The maximum adsorption capacity calculated by non-linear Langmuir model was 492.5 mg/g at pH 5.5. The thermodynamic values suggested that the adsorption process was spontaneous and endothermic. Moreover, after five cycles of adsorption-desorption tests, TAC remained effective at adsorbing uranium, implying the introducing of TA to the precursor (PZS-co-TA) could enhance the adsorption capacity for uranium.

Modular reconstruction and optimization of the trans-4-hydroxy-L-proline synthesis pathway in Escherichia coli.

BACKGROUND: In recent years, there has been a growing demand for microbial production of trans-4-hydroxy-L-proline (t4Hyp), which is a value-added amino acid and has been widely used in the fields of medicine, food, and cosmetics. In this study, a multivariate modular metabolic engineering approach was used to remove the bottleneck in the synthesis pathway of t4Hyp. RESULTS: Escherichia coli t4Hyp synthesis was performed using two modules: a α-ketoglutarate (α-KG) synthesis module (K module) and L-proline synthesis with hydroxylation module (H module). First, α-KG attrition was reduced, and then, L-proline consumption was inhibited. Subsequently, to improve the contribution to proline synthesis with hydroxylation, optimization of gene overexpression, promotor, copy number, and the fusion system was performed. Finally, optimization of the H and K modules was performed in combination to balance metabolic flow. Using the final module H1K4 in a shaking flask culture, 8.80 g/L t4Hyp was produced, which was threefold higher than that produced by the W0 strain. CONCLUSIONS: These strategies demonstrate that a microbial cell factory can be systematically optimized by modular engineering for efficient production of t4Hyp.