A novel adsorbent based on cellulose (CGD) was prepared via modifying with glycidyl methacrylate (GMA) and diethylenetriamine pentaacetic acid (DTPA), characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and differential thermogravimetry (DTA/TGA). Malachite green (MG) and basic fuchsine (BF) were used to resemble cationic dyes in wastewaters. The influences of several parameters (contact time, pH, temperature, initial concentration) were evaluated to determine the best adsorption conditions. Langmuir adsorption isotherm items explained MG adsorption well, while BF was fitted well with the Freundlich model. The maximum adsorption capacities were greater than some other reports, 1155.76 mg•g −1 for a BF internal concentration of 2000 mg•L −1 and 458.72 mg•g −1 for MG in theory. Kinetics and thermodynamics were adopted to explain in-depth information associated with the adsorption process. The adsorption processes of dyes were both feasible spontaneous and well-described by the pseudosecond-order model. The dynamic adsorption/desorption experiments, with saturated sodium bicarbonate solution as the eluent, show that the adsorbent could be reused for five cycles or four cycles, keeping the adsorption rate above 85 % and 90 % for BF and MG, respectively.
A novel
cellulose-based adsorbent (CGS) was synthesized by a facile,
two-step modification route. It was characterized by the FTIR, XRD,
and SEM technique. The adsorption characteristics of CGS were compared
with those of native cellulose using crystal violet (CV) as an adsorbate
in this work. The effects of contact time, temperature, pH, and initial
concentration on the sorption were all investigated. The adsorption
kinetics for both CGS and cellulose were found to follow a pseudo-second-order
(P-S-O) kinetic model. The equilibrium data of CGS fitted well with
the Langmuir isothermal model, and the maximum theoretical adsorption
capacity of CGS for CV was 218.82 mg g–1 at 50 °C;
the adsorption increased by 70.8% compared to that of native cellulose.
A thermodynamics study was also performed. The comparative study confirmed
that the structure of CGS is more conducive for the adsorption of
CV than cellulose. Furthermore, adsorption/desorption experiments
showed that CGS could be reused for at least eight cycles with stable
sorption ability after being regenerated with 50% ethanol solution
(pH 3.0).
A new chiral entity, pentanidium, has been shown to be an excellent chiral phase-transfer catalyst. The enantioselective Michael addition reactions of tert-butyl glycinate-benzophenone Schiff base with various α,β-unsaturated acceptors provide adducts with high enantioselectivities. A successful gram-scale experiment at a low catalyst loading of 0.05 mol % indicates the potential for practical applications of this methodology. Phosphoglycine ester analogues can also be utilized as the Michael donor, affording enantioenriched α-aminophosphonic acid derivatives and phosphonic analogues of (S)-proline.
Zero, one, or two? Guanidinium catalyst 1⋅HBArF4 (ArF=3,5‐(CF3)2C6H3, Bn=benzyl, Ts=4‐toluenesulfonyl) was obtained in a single step from a commercially available diamine. By using this catalyst an asymmetric phospha‐Mannich reaction has been developed, involving secondary phosphine oxides and H‐phosphinates as the P nucleophile. A series of enantiomerically enriched α‐amino phosphine oxides (2), α‐amino phosphinate, and H‐phosphinates containing a P‐chiral center were prepared.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.