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With increasingly stringent regulations, the reduction of NOx emissions during vehicle cold start is a major challenge. Pd-modified zeolites are considered as the most promising passive NOx adsorber (PNA) for cold start NO[sub x] control. Nevertheless, the scarcity and the high cost of Pd limit its practical application. Herein, a non-precious metal modified Co/Na-SSZ-13 zeolite for low-temperature NOx adsorption is reported. This one-pot synthesized Co/Na-SSZ-13 exhibits an extraordinary NOx storage capacity (212 µmol …) under humid conditions (3% H2O v/v), which is more than double that of conventional Co or Pd-modified SSZ-13. This is attributed to the absence of the inert cobalt phyllosilicate commonly found in conventional Co-SSZ-13, as well as the highly dispersed Co and Na ions as the effective NOx adsorption sites in Co/Na-SSZ-13. Moreover, the presence of Na ions shields the negative charge generated by the Al center and weakens the local electric field strength of the Al and Co centers. This lowers the H2O adsorption energy and improves the zeolite hydrophobi city, which enhances the NO storage capacity of the Co/Na-SSZ-13 under humid conditions. This work highlights the Co/Na-SSZ-13, synthesize via a simple and high-efficiency method, as a promising substitute for noble metal PNA materials. [ABSTRACT FROM AUTHOR]

The treatment of wastewater by microalgae cultivation has attracted more and more attention. However, the way to harvest microalgae cells from the wastewater and the treatment of the large quantity of residual solution have become critical issues. In this work, a new approach for the treatment of municipal wastewater is presented. The combination of flocculation for removing mainly microalgae and thereafter membrane filtration for chemical oxygen demand (COD) and conductivity reduction of the residual solution after flocculation is discussed. The COD concentration of the wastewater decreased from 260 to 84 mg/L after flocculation by chitosan. Five ultrafiltration (UF) membranes and two nanofiltration (NF) membranes were used for filtration to find a suitable membrane for COD and conductivity reduction. Among the five UF membranes, GR82PE showed the best performance, whose permeate flux and COD retention at 4 bar were 189.66 L/(m2.h) and 43.03%, respectively. NF membranes showed higher COD and conductivity retentions than UF membranes. The COD retention of Desal5-DK reached 98.3% at 20 bar. Lastly, the flux recovery after the filtration test of each membrane is also discussed. [ABSTRACT FROM AUTHOR]