Yanmei Zhou

Biochar-supported zerovalent iron for removal of various contaminants from aqueous solutions

This work describes the synthesis and testing of a novel environmental sorbent that combines the advantages of biochar, chitosan, and zerovalent iron (ZVI). Chitosan was used as a dispersing and soldering reagent to attach fine ZVI particles onto bamboo biochar surfaces. Characterization of the resulted ZVI-biochar composites (BBCF) indicated that chitosan effectively soldered the iron particles onto carbonaceous surfaces within the biochar pore networks. The BBCF showed enhanced ability to sorb heavy metals (Pb(II), Cr(VI), and As(V)), phosphate (P), and methylene blue (MB) from aqueous solutions. The removal of Pb(II), Cr(VI), and MB by the biochar-supported ZVI was mainly controlled by both the reduction and surface adsorption mechanisms. Removal of anionic contaminants (As(V) and P) was likely controlled by electrostatic attraction with the iron particles on the BBCF surfaces. An additional benefit is that the contaminant-laden BBCF could be removed from aqueous solution easily by magnetic attraction.

Effective removal of cationic dyes using carboxylate-functionalized cellulose nanocrystals.

A novel carboxylate-functionalized adsorbent (CNM) based on cellulose nanocrystals (CNCs) was prepared and adsorptive removal of multiple cationic dyes (crystal violet, methylene blue, malachite green and basic fuchsin) were investigated. The maximum cationic dyes uptakes ranged from 30.0 to 348.9mgg(-1) following the order of: CNM>CNCs>raw cellulose. Furthermore, the removal of crystal violet by CNM was investigated representatively where kinetics, thermodynamics and isotherm analysis were employed to explain in-depth information associated with the adsorption process. The adsorption kinetics fitted well to the pseudo-second-order model and thermodynamic analysis revealed that the adsorption process was spontaneous and exothermic. Meanwhile, isothermal study demonstrated a monolayer adsorption behavior following the Langmuir model with a calculated maximum absorption capacity of 243.9mgg(-1), which is higher than those of many other reported adsorbents. These findings prefigure the promising potentials of CNM as a versatile adsorbent for the efficient removal of cationic dyes from wastewater.

Improved removal of malachite green from aqueous solution using chemically modified cellulose by anhydride.

Cellulose modified with maleic (M) and phthalic (P) anhydride, to be named CMA and CPA, were tested as feasible adsorbents for the removal of malachite green from aqueous solution. At the same time, the uptake ability of natural cellulose was also studied for comparison. The structure of material was characterized by FT-IR and XRD. The effects of solution pH, initial dye concentration, contact time and temperature were investigated in detail by batch adsorption experiments. The kinetic and isotherm studies suggested that the adsorption followed the pseudo-second-order model and Langmuir isotherm. The maximum adsorption capacity on CMA and CPA were 370 mg g(-1) and 111 mg g(-1), respectively. Furthermore, the thermodynamics studies indicated the spontaneous nature of adsorption of malachite green on adsorbents. All the studied results showed that the modified cellulose could be used as effective adsorption material for the removal of malachite green from aqueous solutions.

5-Hydroxymethylfurfural modified rhodamine B dual-function derivative: Highly sensitive and selective optical detection of pH and Cu2+

A dual-function optical chemosensor (RBF) was designed and easily synthesized by condensation reaction of 5-Hydroxymethylfurfural and rhodamine B hydrazide. RBF exhibited highly sensitive, highly selective and quick response to acidic pH. The fluorescence intensity of RBF exhibited a more than 41-fold increase within the pH range from 7.50 to 3.73 with a pKa value of 5.02, which could be successfully applied to monitor intracellular pH in living PC12 cells and HeLa cells. Additionally, the spectroscopy of UV-Vis and EDTA-adding experiments indicated that RBF was a highly selective and reversible colorimetric chemosensor for Cu(2+) in Tris-HCl (10mM, pH=7.2) aqueous buffer solution as well as other metal ions had no obvious interference. Moreover, RBF has been successfully applied to detect Cu(2+) in real water samples.

A simple-structured acridine derivative as a fluorescent enhancement chemosensor for the detection of Pd2+ in aqueous media.

4,5-Bis(hydroxymethyl) acridine (sensor 1) has been discovered and synthesized as a simple-structured Pd(2+) fluorescent probe. Sensor 1 showed highly selective recognition toward Pd(2+) over other examined metal ions in aqueous solution. Under the optimized condition, fluorescence intensity was linearly proportional to the concentration of Pd(2+) in the 0-1 μM concentration range with detection limits of 0.021 μM. The EDTA-adding and stoichiometry experiments indicated that sensor 1 was a reversible chemosensor for Pd(2+) with a 2:1 ligand/metal complex at neutral pH. Moreover, the sensor 1 was also successfully applied to determination of Pd(2+) in water samples and palladium-containing catalyst, which made it attractive for sensing applications.

A new Schiff base based on vanillin and naphthalimide as a fluorescent probe for Ag+ in aqueous solution

A new Schiff base based on vanillin and naphthalimide was designed and synthesized as fluorescent probe. The probe showed high selectivity for Ag(+) over other metal ions such as Pb(2+), Na(+), K(+), Cd(2+), Ba(2+), Cr(3+), Zn(2+), Cu(2+), Ni(2+), Ca(2+), Al(3+) and Mg(2+) in aqueous solution. A new fluorescence emission was observed at 682 nm in the presence of Ag(+) ion. The fluorescence intensity quenched with increasing the concentration of Ag(+) at 682 nm. The method of jobs plot confirmed the 1:2 complex between Ag(+) and probe, and the mechanism was proposed.

A novel “turn-on” fluorogenic probe for sensing hypochlorous acid based on BODIPY

A highly selective and sensitive boron-dipyrromethene (BODIPY) based fluorescent probe (Bodipy-Hy) for the detection of hypochlorous acid (HOCl) was designed and easily synthesized by the condensation reaction (CN) of BODIPY aldehyde (BODIPY-AL) and hydrazine hydrate, which contain a newer group compared with other similar probes. With the specific HOCl-promoted oxidation grade of the CN bond increasing, the fluorescence intensity of Bodipy-Hy gradually increased more than 11-fold. And the fluorescent quantum yield enhances from 0.06 to 0.62. A linear increase of fluorescence intensity could be observed under the optimum conditions with increasing HOCl concentration over a wide linear range 0–22.5 μM, then a lower detection limit of 56 nM based on 3 × δblank/k was obtained. Moreover, the probe can also be successfully applied to imaging HOCl in living cells with low cytotoxicity.

A highly selective fluorescent probe for Al3+ based on 4-aminoantipyrine

A novel and simple Schiff base based on 2-pyridine formaldehyde and 4-aminoantipyrine was synthesized and characterized as a fluorescent probe. In the presence of Al(3+), the fluorescent intensity has a dramatic enhancement over other examined metal ions in aqueous solution. The method of Jobs plot indicated the formation of 1:1 complex between probe and Al(3+), and the possible binding mode of the system was also proposed. Moreover, other examined metal ions had no effect on the detection of Al(3+).

Removal of Chromium (VI) from Aqueous Solution by Cellulose Modified with D-Glucose

Cellulose powder was grafted with the vinyl monomer glycidyl methacrylate using ceric ammonium nitrate as initiator and was further derived with D-Glucose (D-Glu) to build a adsorbent (Cell-g-GMA-D-Glu). Epoxy cellulose, which was made up of Cell-g-GMA and Cell-hydro-g-GMA, was found to contain 5.48 mmol g−1 epoxy groups. The adsorption process of the adsorbent was described by the Langmuir model of adsorption well and the maximum adsorption capacity of chromium (VI) reached to 54.59 mg g−1. The adsorption-desorption tests of the Cell-g-GMA-D-Glu exhibited that the reproducibility of the absorbent was well and the adsorbent could be reused six times at least.

A “turn-on” fluorescent probe used for the specific recognition of intracellular GSH and its application in bioimaging

We have designed and synthesized a carbazole-based fluorescent probe (CZ-Nm) for the specific recognition of GSH over Cys and Hcy. The probe is almost non-fluorescent owing to the photoinduced electron transfer (PET) process from the carbazole fluorophore to the nitroolefin moiety. Upon treatment with GSH, owing to the Michael addition of GSH to the double bond of the nitroolefin moiety, the probe shows a fluorescence enhancement and absorption change. The CZ-Nm probe displays desirable properties such as acting as a “naked eye” probe, a wide linear range of 0–0.01 M, high sensitivity, and strong anti-jamming capability. More importantly, the probe can also be successfully applied to the detection of intracellular GSH with a bright fluorescence signal, good cell permeability and bio-compatibility.