Graphene oxide (GO)-thionine (TH) nanocomposite was prepared by π-π stacking. The nanocomposite was cast-coated on a glassy carbon electrode (GCE) to prepare an electroreduced GO (ERGO)-TH/GCE, then 2-mercaptoethanesulfonate (MES) was covalently tethered to ERGO-TH by potentiostatic anodization to form an ERGO-TH-MES/GCE. The thiolation reaction was monitored by electrochemical quartz crystal microbalance (EQCM). Square wave anodic stripping voltammetry (SWASV) was used to determine Cd(2+) and Pb(2+) at the ERGO-TH-MES/GCE further modified with Nafion and Bi. Under the optimal conditions, the linear calibration curves for Cd(2+) and Pb(2+) are from 1 to 40 μg L(-1), with limits of detection (S/N=3) of 0.1 μg L(-1) for Cd(2+) and 0.05 μg L(-1) for Pb(2+), respectively. The electrode was used for the simultaneous analysis of Cd(2+) and Pb(2+) in water samples with satisfactory recovery.

A nanocomposite film is prepared by cyclic voltammetric deposition of electroreduced graphene oxide (ERGO) and polythionine (PTH) on a glassy carbon (GC) electrode. The electrodeposition of ERGO–PTH film is also investigated via the electrochemical quartz crystal microbalance (EQCM) method for more in-depth understanding of the process. The ERGO–PTH nanocomposite film is applied as transducer for facilitated electrocatalytic oxidation of NADH and for the construction of dehydrogenase-based amperometric biosensor. Under optimum conditions, the amperometric detection of NADH provides a wide linear detection range (0.01–3.9mM), a high sensitivity (143μAmM−1cm−2) and a low limit of detection (LOD=0.1μM, S/N=3). With alcohol dehydrogenase (ADH) as a model, we obtain a linear amperometric response of the ADH-modified ERGO–PTH/GC electrode to ethanol concentration from 0.05 to 1.0mM, a sensitivity of 2.8μAmM−1cm−2, and a LOD of 0.3μM (S/N=3).

We report on the thiol-ene chemistry guided preparation of a novel thiolated polymeric nanocomposite involving polyaniline (PANI), a functionalized thiol, e.g., sulfur-rich 2,5-dimercapto-1,3,4-thiadiazole (DMcT), and multiwalled carbon nanotubes (MWCNTs) for the sensitive differential pulse anodic stripping voltammetric determination of Cd(2+) and Pb(2+) on a glassy carbon electrode (GCE). Briefly, the thiol-ene reaction of a thiol with oxidized PANI that was chemically synthesized in the presence of solution-dispersed acidified MWCNTs yielded a thiolated polymeric nanocomposite of thiol-PANI/MWCNTs. The thiols examined include DMcT, 1,6-hexanedithiol and β-mercaptoethanol. Quartz crystal microbalance, cyclic voltammetry, scanning electron microscopy, Fourier transform infrared spectroscopy and ultraviolet-visible spectroscopy were used for film characterization and process monitoring. Under the optimized conditions, the obtained Bi/Nafion/DMcT-PANI/MWCNTs/GCE can sensitively sense Cd(2+) and Pb(2+) with limits of detection of 0.01 and 0.04 μg L(-1), respectively.

•Multiwalled carbon nanotube (MWCNT)-thiolated polyaniline nanocomposite film.•Thiol-ene reaction between oxidized polyaniline and mercaptosuccinic acid.•MWCNTs-enhanced electroactivity of thiolated polyaniline at neutral pH.•Improved catalytic electroanalysis of ascorbic acid.

We report on the thiol-ene chemistry guided preparation of novel thiolated polymeric nanocomposite films of abundant anionic carboxylic groups for electrostatic enrichment and sensitive electroanalysis of cationic dopamine (DA) in neutral solution. Briefly, the thiol-ene nucleophilic reaction of a carboxylated thiol with oxidized polypyrrole (PPy), which was electrosynthesized on an Au electrode in the presence of solution-dispersed acidified multiwalled carbon nanotubes (MWCNTs), produced an a PPy-thiol-MWCNTs/Au electrode, and the PPy can be electrochemically overoxidized (OPPy) to form an OPPy-thiol-MWCNTs/Au electrode. The carboxylic groups of the polymeric nanocomposite film originate from the acidified MWCNTs, PPy-tethered carboxylated thiol, and OPPy. The carboxylated thiols examined are mercaptosuccinic acid (MSA) and thioglycolic acid, with β-mercaptoethanol as a control. Electrochemical quartz crystal microbalance, scanning electron microscopy, Fourier transform infrared spectroscopy and ultraviolet-visible spectroscopy were used for film characterization and process monitoring. Under the optimized condition, the differential pulse voltammetry peak current of DA oxidation at OPPy-MSA-MWCNTs/Au electrode is linear with DA concentration from 1.00×10(-9) to 2.87×10(-6) mol L(-1), with a limit of detection of 0.4 nmol L(-1), good anti-interferent ability and stability.

We report on a glassy carbon electrode (GCE) modified with a lead ionophore and multiwalled carbon nanotubes. It can be applied to square wave anodic stripping voltammetric determination of Pb(II) ion after preconcentration of Pb(II) at −1.0 V (vs. SCE) for 300 s in pH 4.5 acetate buffer containing 400 μg L−1 of Bi(III). The ionophore-MWCNTs film on the GCE possesses strong and highly selective affinity for Pb(II) as confirmed by quartz crystal microbalance experiments. Under the optimum conditions, a linear response was observed for Pb(II) ion in the range from 0.3 to 50 μg L−1. The limit of detection (at S/N = 3) is 0.1 μg L−1. The method was applied to the determination of Pb(II) in water samples with acceptable recovery.

Angiotensin converting enzyme (ACE) plays a pivotal role in blood pressure regulation, and its interaction with an ACE inhibitor (ACEI) is an important research topic for treatment of hypertension. Herein, a low reagent consumption, multiparameter and highly sensitive quartz crystal microbalance (QCM) at 35-MHz fundamental frequency was utilized to monitor in situ the binding process of solution lisinopril (LIS, a carboxylic third-generation ACEI) to ACE adsorbed at a 1-dodecanethiol (C12SH)-modified Au electrode. From the QCM data, the binding molar ratio (r) of LIS to adsorbed ACE was estimated to be 2.3:1, and the binding and dissociation rate constants (k1 and k−1) and the binding equilibrium constant (Ka) were estimated to be k1 = 4.1 × 106 L mol−1 s−1, k−1 = 7.3 × 10−3 s−1 and Ka = 5.62 × 108 L mol−1, respectively. Comparable qualitative and quantitative results were also obtained from separate experiments of cyclic voltammetry, electrochemical impedance spectroscopy and surface plasmon resonance measurements.

Differential pulse anodic stripping voltammetry was applied to detect Pb2+ and Cd2+ at a glassy carbon electrode modified with Nafion, poly(2,5-dimercapto-1,3,4-thiadiazole) (PDMcT), and multiwalled carbon nanotubes (MWCNTs). Preconcentration was accomplished at −1.0 V vs. SCE in pH 5 buffer containing 400 μg L−1 Bi3+ for 6 min and resulted in high sensitivity, selectivity and reproducibility. Electrochemical quartz crystal microbalance studies revealed that PDMcT is cleaved under the reductive conditions to form thiol groups that bind Pb2+ and Cd2+ ions, whilst the Nafion binder stabilizes the film and the MWCNTs improve electroactivity. The presence of the bismuth film improves sensitivity and reproducibility. Under optimum conditions, the electrode responds linearly to Cd2+ ions in the concentration range from 0.05 to 20 μg L−1, and to Pb2+ from 0.1 to 22 μg L−1. The limits of detection (S/N = 3) are 0.03 and 0.05 μg L−1, respectively. This method was successfully applied to the determination of the two ions in water samples.

The aim of this work is to evaluate the adsorption performances of activated carbon derived from sewage sludge (ACSS) for gaseous formaldehyde removal compared with three commercial activated carbons (CACs) using self-designing adsorption and distillation system. Formaldehyde desorption of the activated carbons for regeneration was also studied using thermogravimetric (TG) analysis. The porous structure and surface characteristics were studied using N2 adsorption and desorption isotherms, scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). The results show that ACSS has excellent adsorption performance, which is overall superior to the CACs. Adsorption theory indicates that the ACSS outperforms the CACs due to its appropriate porous structure and surface chemistry characteristics for formaldehyde adsorption. The TG analysis of desorption shows that the optimum temperature to regenerate ACSS is 75°C, which is affordable and economical for recycling.

Fine particulate matter is believed to be more toxic than coarse particles and to exacerbate health problems such as respiratory and cardiopulmonary diseases. Specific organic compounds within atmospheric fine particulate material can be used to differentiate specific inputs from various emissions and thus is helpful in identifying the major urban air pollution sources that contribute to these health problems. Particular marker compounds that carry signature information about different emission sources (i.e., gasoline or diesel motor vehicles, wood smoke, meat cooking, vegetative detritus, and cigarette smoke) are reviewed. Aerosol organic types (e.g., from mass spectrometry data, which can also help in elucidation of carbonaceous material sources) are also discussed. Apportionment of the primary source contributions and atmospheric processes contributing to fine particulate matter and fine particulate organic material concentrations are outlined. This review provides an overview of the latest developments in chemical characterization approaches for identification and quantification of compounds in complex organic mixtures associated with fine atmospheric particles and their use in chemical mass balance (CMB) and positive matrix factorization (PMF) source apportionment models.

A series of transition metal-doped VPO composite catalysts were prepared by impregnating method, and were employed to catalyze reaction of cyclohexane with nitrosyl sulfuric acid in the presence of fuming sulfuric acid. To our delight, ε-caprolactam was directly obtained from such one-step catalytic process. It was found that Mn/AlVPO gave the best results with 9.8% of conversion and 72.9% of selectivity to ε-caprolactam among present composite catalysts. While the conversion and selectivity are not high at this time to be commercially viable, this discovery establishes a potential new one-step process for making ε-caprolactam from cyclohexane.

Modifications of alkylation, chlorination and Vilsmeier reaction were employed for the synthesis of aromatic aldehydes bearing nitrogen mustard derivatives and halogenoalkylpiperazinyl. Thus seven new aromatic aldehydes were synthesized from commercially available aniline and phenylpiperazine by the modified method. All of the desired compounds were characterized by MS, IR, H-1 NMR spectra and elemental analysis.