PLA/CS-ZnO bionanocomposite for rapid catalytic reduction of nitrophenol compounds as a heterogeneous nanocatalyst.

In this research, a high efficiency and environmentally friendly method to reduce nitrophenol compounds such as 4-nitrophenol (4-NP), 2,4,6-trinitrophenol (2,4,6-TNP) and 2,4-dinitrophenol (2,4-DNP) was used in the presence of poly(lactic acid)/chitosan-ZnO ( PLA/CS-ZnO) bionanocomposite. Using FT-IR, SEM, XRD and UV-Vis techniques, PLA/CS-ZnO bionanocomposite was identified after synthesis. Also, the mechanical properties of the bionanocomposite were investigated using the stress-strain curve. The mentioned bionanocomposite showed a very good efficiency in reducing nitrophenol compounds to aminophenolic compounds, so that under optimal conditions, 100% conversion and selectivity in the reduction of 4-NP, 2,4,6-TNP and 2,4-DNP to 4-aminophenol (4-AP), 2,4,6-triaminophenol (2,4,6-TAP) and 2,4-diaminophenol (2,4-DAP) were observed. UV-Vis absorption spectrum at different times were used to evaluate the progress of the reaction. Furthermore, after the reaction, PLA/CS-ZnO was recovered and used for the next cycle. The results showed that the bionanocomposite can perform ten consecutive cycles without a significant decrease in efficiency. The comparison of catalytic activity with other catalysts showed that the bionanocomposite synthesized in the present research has a higher efficiency in reduction of nitrophenol compounds.

Modified activated carbon derived from chestnut oak shells as a new sorbent for the needle-trap extraction.

In this study, an acid-treated-activated carbon was prepared from chestnut oak shell carbonization followed by modification with hydrochloric acid/nitric acid and then used as a new sorbent for headspace needle-trap extraction of chlorophenol compounds from aqueous solutions. Different techniques, including scanning electron microscopy, nitrogen adsorption-desorption analysis, and Fourier transform-infrared spectroscopy were used for the characterization of the sorbents. The effects of some experimental parameters, including the temperature, pH, sorbent amount, and time of extraction were optimized. The developed method is fast and sensitive, providing low and sub ng/L detection limits. The limits of detection and quantification were in the range of 0.75-5 and 5-15 ng/ml, respectively, and the equilibrium time was 20 min. Wide linearity in the range of 15-2000 ng/L with R2  > 0.9993 was obtained. Repeatability of the method was accessed at 50, 100, and 200 ng/L concentration levels and RSD% of 5%-12% was achieved. The introduced method was applied for analyzing real water samples containing spiked chlorophenols, and the relative recovery values were found to be in the range of 84%-99% at the concentration levels of 50, 100 and 200 ng/L.

Highly Reactive Heterogeneous Nanofibers Catalyst based on [Mo154] Clusters for Green Aerobic Oxidation of Sulfur Mustard Analogues under Ambient Conditions.

BACKGROUND: Due to the increasing chemical and biological threats posed by terrorist attacks, there is a need to design and prepare nanofibers (NFs) with the ability to neutralize CWAs. For this purpose polyacrylonitrile NFs and polyoxomolybdate [Mo154] (abbreviated as PAN NFs/[Mo154]) as a heterogeneous catalyst was prepared by electrospinning method with a diameter of about 100nm. OBJECTIVE: The PAN NFs/[Mo154] catalyze the selective aerobic oxidation of sulfur mustard stimulants, such as 2-chloroethyl ethyl sulfide (2-CEES) and 2-chloroethyl phenyl sulfide (2-CEPS) under green and "ambient" conditions (25 °C, 1atm O2) in the presence of ethanol with high efficiency and selectivity. 2-CEES was selected as a model reaction to optimize the parameters of the reaction. METHODS: The progress of the reaction was evaluated after different times using GC-FID, GCMS and TLC. The reaction product was also confirmed by 1H-NMR spectroscopy. RESULTS: The aerobic oxidation results of 2-CEES showed that PAN NFs/[Mo154] have a conversion of 98% to produce only a nontoxic product, 2-CEESO with the selectivity of 100% after 45min. The results were performed using [Mo154] without any PAN NFs for comparison whereas [Mo154] converts only 52% of 2-CEES under identical conditions. CONCLUSION: Heterogeneous PAN NFs/[Mo154] catalyst was reused after washing with solvent up to 5 steps without leaching of [Mo154] from PAN NFs and without any loss in efficiency due to the morphology of NFs. In addition to the recovery of PAN NFs/[Mo154] in different cycles, the use of FT-IR, UV-Vis and TEM techniques confirms the stability and morphology of PAN NFs/[Mo154] after the fifth cycle, 2-CEES oxidation. According to our information, this report is the first use of PAN NFs enriched with [Mo154] for aerobic oxidation of sulfur mustard simulants.

Catalytic epoxidation activity of keplerate polyoxomolybdate nanoball toward aqueous suspension of olefins under mild aerobic conditions.

Catalytic efficiency of a sphere-shaped nanosized polyoxomolybdate {Mo132} in the aerobic epoxidation of olefins in water at ambient temperature and pressure in the absence of reducing agent is exploited which resulted good-to-high yields and desired selectivity.