Removal of Zn(II), Mn(II) and Cu(II) by adsorption onto banana stalk biochar: adsorption process and mechanisms.

Low-cost banana stalk (Musa nana Lour.) biochar was prepared using oxygen-limited pyrolysis (at 500 °C and used), to remove heavy metal ions (including Zn(II), Mn(II) and Cu(II)) from aqueous solution. Adsorption experiments showed that the initial solution pH affected the ability of the biochar to adsorb heavy metal ions in single- and polymetal systems.

EDTAD-modified cassava stalks loaded with FeO: highly efficient removal of Pb and Zn from aqueous solution.

In this study, a novel magnetic cassava stalk composite (M-EMCS) was prepared through modification with ethylenediamine tetraacetic anhydride (EDTAD) and loading of FeO. The surface morphology, molecular structure, and magnetic characteristics of the composite were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), vibrating-sample magnetometer (VSM), and X-ray diffraction (XRD). It was shown that EDTAD and FeO were successfully modified and loaded in cassava straw (CS), respectively.

A sensitive magnetic nanoparticle-based immunoassay of phosphorylated acetylcholinesterase using protein cage templated lead phosphate for signal amplification with graphite furnace atomic absorption spectrometry detection.

We developed a new magnetic nanoparticle sandwich-like immunoassay using protein cage nanoparticles (PCN) for signal amplification together with graphite furnace atomic absorption spectrometry (GFAAS) for the quantification of an organophosphorylated acetylcholinesterase adduct (OP-AChE), the biomarker of exposure to organophosphate pesticides (OPs) and nerve agents. OP-AChE adducts were firstly captured by titanium dioxide coated magnetic nanoparticles (TiO2-MNPs) from the sample matrixes through metal chelation with phospho-moieties, and then selectively recognized by anti-AChE antibody labeled on PCN which was packed with lead phosphate in its cavity (PCN-anti-AChE). The sandwich-like immunoreaction was performed among TiO2-MNPs, OP-AChE and PCN-anti-AChE to form a TiO2-MNP/OP-AChE/PCN-anti-AChE immunocomplex.

One-step displacement dispersive liquid-liquid microextraction coupled with graphite furnace atomic absorption spectrometry for the selective determination of methylmercury in environmental samples.

A novel method for the selective determination of methylmercury (MeHg) was developed by one-step displacement dispersive liquid-liquid microextraction (D-DLLME) coupled with graphite furnace atomic absorption spectrometry. In the proposed method, Cu(II) reacted with diethyldithiocarbamate (DDTC) to form Cu-DDTC complex, which was used as the chelating agent instead of DDTC for the dispersive liquid-liquid microextraction (DLLME) of MeHg. Because the stability of MeHg-DDTC is higher than that of Cu-DDTC, MeHg can displace Cu from the Cu-DDTC complex and be preconcentrated in a single DLLME procedure.

A label-free DNAzyme-cleaving fluorescence method for the determination of trace Pb(2+) based on catalysis of AuPd nanoalloy on the reduction of rhodamine 6G.

The substrate chain of double-stranded DNA (dsDNA) could be specifically cleaved by Pb(2+) to release single-stranded DNA (ssDNA) that adsorbs onto the AuPd nanoalloy (AuPdNP) to form a stable AuPdNP-ssDNA complex, but the dsDNA can not protect AuPdNPs in large AuPdNP aggregates (AuPdNPA) under the action of NaCl. AuPdNP-ssDNA and large AuPdNPA could be separated by centrifugation. On increasing the concentration of Pb(2+) , the amount of released ssDNA increased; AuPdNP-ssDNA increased in the centrifugation solution exhibiting a catalytic effect on the slow reaction of rhodamine 6G (Rh6G) and NaH2 PO2 , which led to fluorescence quenching at 552 nm.

Catalysis of aptamer-modified AuPd nanoalloy probe and its application to resonance scattering detection of trace UO(2)2+.

AuPd nanoalloy and nanopalladium with a diameter of 5 nm were prepared, using sodium citrate as the stabilizing agent and NaBH(4) as the reductant. The nanocatalyst containing palladium on the surface exhibited a strong catalytic effect on the slow NiP particle reaction between NiCl(2) and NaH(2)PO(2), and the NiP particle system showed a resonance scattering (RS) peak at 508 nm. The RS results showed that the Pd atom on AuPd nanoalloy surface is the catalytic center.

[Resonance scattering detection of trace Hg2+ using herring sperm DNA modified nanogold].

In pH 7.0 tris-HCl buffer solutions and in the presence of 0.017 mol x L(-1) NaCl, herring sperm DNA was combined with gold nanoparticles in size of 10 nm to form stable complex, and the NaCl did not cause the aggregation of the gold nanoparticles.

A novel and selective spectral method for the determination of trace chlorine in water basing on the resonance scattering effect of rhodamine B-I(3) association nanoparticles.

In Na(2)HPO(4)-citric acid buffer solution, Cl(2) can oxidize I(-) to form I(2) and then it reacts with excess I(-) to form I(3)(-). The I(3)(-) combines respectively with rhodamine dyes, including rhodamine B (RhB), butyl rhodamine B (b-RhB), rhodamine 6G (RhG) and rhodamine S (RhS), to form association particles which give stronger resonance scattering (RS) effect at 400 nm. The RS intensity of the RhB, b-RhB, RhG and RhS systems is proportional to chlorine concentrations in the range of 0.

[A fluorescence quenching method for the determination of trace chlorite in water with rhodamine B].

In acidic sodium acetate-HCl buffer solution containing KI, Rhodamine B (RhB) has a fluorescence peak at 580 nm. When ClO2(-) exists fluorescence quenching occur. The fluorescence quenching intensity is linear with the concentration of ClO2(-) in the range of 0.

A novel, simple and sensitive resonance scattering spectral method for the determination of chlorite in water by means of rhodamine B.

A new resonance scattering method was proposed for the determination of chlorite, basing on the resonance scattering effect of rhodamine dye. In HCl-sodium acetate buffer solution, chlorite oxidizes I- into I2 and the reaction of I2 and excess I- results in I3- It is respectively combined with rhodamine dyes, including rhodamine B (RhB), butyl rhodamine B (b-RhB), rhodamine G (RhG) and rhodamine S (RhS), to form association complex particles, which exhibit stronger resonance scattering (RS) effect at 400 nm. The chlorite concentration of ClO2- in the range of 0.

[A new fluorescence quenching method for the determination of trace ClO2 in water using silver nanoparticles].

In pH 9.1 NH4Cl-NH3 x H2O buffer solution, there is a fluorescence peak at 470 nm for silver nanoparticles. A fluorescence quenching takes place when it was oxidized by ClO2.

Resonance scattering effect of rhodamine dye association nanoparticles and its application to respective determination of trace ClO2 and Cl2.

A new resonance scattering method, based on resonance scattering (RS) effect, for the respective determination of ClO2 and Cl2 in water samples was developed. In HCl-NaAc buffer solutions with the pH value of 1.42, chlorine dioxide, or chlorine, oxidizes I- to form 12, which then reacts with the excess I- to form I3-.

Luminescence properties of metal(II)-diethyldithiocarbamate chelate complex particles and its analytical application.

In a suitable pH buffer solutions, sodium diethyldithiocarbamate (DDTC) reacts with some divalence metal ions M(II) to form (M-DDTC)( n ) chelate complex nanoparticles, which exhibit different luminescence properties. There is a strongest luminescence peak at 470 nm for the Co(II)-DDTC system, three peaks at 330, 470, and 630 nm for the Cu(II)-DDTC system, three peaks at 420, 470, and 630 nm for the Cd(II)-DDTC system, four peaks at 350, 400, 435, and 470 nm for the Ni(II)-DDTC system, two peaks at 408 and 470 nm for the Pb(II)-DDTC system, two peaks at 415 and 470 nm for the Fe(II)-DDTC system. The different luminescence properties of (M-DDTC)( n ) chelate complex nanoparticles was explained.

[Effect of cation surfactants on absorption spectra of silver nanoparticle in liquid phase].

Yellow Ag nanoparticles, with diameter of 20 nm, exhibit a resonance absorption peak at 400 nm. After adding some cation surfactants (CS), the absorbance at 400 nm becomes weak, (namely, there exists hypochromic effect), but the absorbance at wavelengths longer than 400 nm is enhanced and shows a red shift. When adding concentration of CS, the absorbance at wavelengths longer than 400 nm becomes weak again, the peak at 400 nm is enhanced (namely, there exists hyperchromic effect) and the absorption peaks show a blue shift.

[Spectral properties of the association particle system of quinine-[PtI6]2- and its analytical application].

In 0.01 mol x L(-1) HCl medium, red color [PtI6]2- and quinine combine to form association molecule. The molecules aggregate automatically owing to strong hydrophobic and molecular forces.

[Study on spectral properties of the associated particle of berberine-PHLO and its analytical application].

In neutral medium, berberine forms a red-violet association microparticle with PHLO which has an maximum absorption at 560 nm, Beer's law is obeyed for berberine in the concentration range of 6.65 x 10(-7)-7.71 x 10(-5) mol x L(-1).

A new and sensitive resonance-scattering method for determination of trace nitrite in water with rhodamine 6G.

In the medium HCl-KI-rhodamine dye, NO(2) (-) reacts with excess I(-) to form I(3) (-) and the I(3) (-) and rhodamine dye combine to form an association particle which gives three resonance-scattering (RS) peaks at 320 nm, 400 nm, and 595 nm. In systems containing rhodamine 6G (Rh6G), rhodamine B (RhB), rhodamine S (RhS), and butyl rhodamine B (BRhB) the resonance scattering intensity at 400 nm is proportional to nitrite concentrations in the range 2.3-276 ng mL(-1), 9.