Guide Yang

Mesoporous carbon nitride based biosensor for highly sensitive and selective analysis of phenol and catechol in compost bioremediation.

Herein, we reported here a promising biosensor by taking advantage of the unique ordered mesoporous carbon nitride material (MCN) to convert the recognition information into a detectable signal with enzyme firstly, which could realize the sensitive, especially, selective detection of catechol and phenol in compost bioremediation samples. The mechanism including the MCN based on electrochemical, biosensor assembly, enzyme immobilization, and enzyme kinetics (elucidating the lower detection limit, different linear range and sensitivity) was discussed in detail. Under optimal conditions, GCE/MCN/Tyr biosensor was evaluated by chronoamperometry measurements and the reduction current of phenol and catechol was proportional to their concentration in the range of 5.00 × 10(-8)-9.50 × 10(-6)M and 5.00 × 10(-8)-1.25 × 10(-5)M with a correlation coefficient of 0.9991 and 0.9881, respectively. The detection limits of catechol and phenol were 10.24 nM and 15.00 nM (S/N=3), respectively. Besides, the data obtained from interference experiments indicated that the biosensor had good specificity. All the results showed that this material is suitable for load enzyme and applied to the biosensor due to the proposed biosensor exhibited improved analytical performances in terms of the detection limit and specificity, provided a powerful tool for rapid, sensitive, especially, selective monitoring of catechol and phenol simultaneously. Moreover, the obtained results may open the way to other MCN-enzyme applications in the environmental field.

Effective removal of Cr(VI) through adsorption and reduction by magnetic mesoporous carbon incorporated with polyaniline

Magnetic mesoporous carbon incorporated with polyaniline (PANI–Fe/OMC) is developed for enhanced adsorption and reduction of toxic Cr(VI) to non-toxic Cr(III). Several physicochemical techniques including TEM, FTIR and XPS analyses confirmed that magnetic iron nanoparticles and amino groups have been successfully bound on the mesoporous matrix. The adsorption capacity of the functionalized material is two- and ten-fold that of the magnetic mesoporous carbon (Fe/OMC) and pristine mesoporous silicon (SBA-15), respectively. Solution pH exhibited a remarkable impact on the Cr(VI) adsorption and the maximum uptake amount (172.33 mg g−1) occurred at pH 2.0. The good fitting of adsorption process using pseudo-second-order and Langmuir models indicated the chemisorption process of Cr(VI) removal. The regeneration study revealed that PANI–Fe/OMC can be reused without loss of their activity in repetitive adsorption tests. Moreover, the resultant adsorbent can be effectively applied in actual wastewater treatment due to the excellent removal performance in fixed-bed column and real water samples. The interaction between Cr(VI) and PANI–Fe/OMC was investigated by FTIR and XPS analyses. The results indicate that the amino groups on the surface of PANI–Fe/OMC are involved in Cr(VI) uptake, and simultaneously some toxic Cr(VI) are reduced to non-toxic Cr(III) during the removal process.

Highly effective adsorption of cationic and anionic dyes on magnetic Fe/Ni nanoparticles doped bimodal mesoporous carbon.

Magnetic Fe/Ni nanoparticles doped bimodal mesoporous carbon (MBMC) was prepared for highly effective adsorption of cationic dye methylene blue (MB) and anionic dye methyl orange (MO). Structure characterization demonstrated that Fe/Ni nanoparticles were embedded into the interior of the mesoprous carbon, and MBMC maintained ordered and bimodal mesopores. The effects of several parameters such as contact time, pH, temperature, ionic strength and dye molecular structure on the adsorption were investigated. Alkaline pH was better for MB adsorption, while acidic pH was more favorable for MO uptake. The adsorption capacity was slightly enhanced when existing ion concentrations increased. Adsorption on MBMC was affected by the molecular structures of different dyes, and both primary and secondary pores of MBMC were involved in dye adsorption. The adsorption kinetics fitted well with pseudo-second-order model and exhibited 3-stage intraparticle diffusion mode. Equilibrium data were best described by Langmuir model, and the estimated maximum adsorption capacity for MB and MO was 959.5mg/g and 849.3mg/g, respectively. Thermodynamic studies indicated that the adsorption process was spontaneous and endothermic. Moreover, the adsorbent could be regenerated using ethanol, and the regenerated adsorbent after seven cycles could retain over 80% of the adsorption capacity for the fresh adsorbent. The results suggested that MBMC could be considered as very effective and promising materials for both anionic and cationic dyes removal from wastewater.

Rapid adsorption of 2,4-dichlorophenoxyacetic acid by iron oxide nanoparticles-doped carboxylic ordered mesoporous carbon.

The ordered mesoporous carbon composite functionalized with carboxylate groups and iron oxide nanoparticles (Fe/OMC) was successfully prepared and used to adsorb 2,4-dichlorophenoxyacetic acid (2,4-D) from wastewater. The resultant adsorbent possessed high degree of order, large specific surface area and pore volume, and good magnetic properties. The increase in initial pollutant concentration and contact time would make the adsorption capacity increase, but the pH and temperature are inversely proportional to 2,4-D uptake. The equilibrium of adsorption was reached within 120 min, and the equilibrated adsorption capacity increased from 99.38 to 310.78 mg/g with the increase of initial concentration of 2,4-D from 100 to 500 mg/L. Notablely, the adsorption capacity reached 97% of the maximum within the first 5 min. The kinetics and isotherm study showed that the pseudo-second-order kinetic and Langmuir isotherm models could well fit the adsorption data. These results indicate that Fe/OMC has a good potential for the rapid adsorption of 2,4-D and prevention of its further diffusion.

Phosphorus-doped ordered mesoporous carbons embedded with Pd/Fe bimetal nanoparticles for the dechlorination of 2,4-dichlorophenol

Palladium/iron (Pd/Fe) bimetallic nanoparticles were embedded within phosphorus-doped ordered mesoporous carbons (Pd/NZVI@P) with high dechlorination activity for 2,4-dichlorophenol (2,4-DCP). The Pd/Fe bimetal nanoparticles of about 15 nm diameter embedded in phosphorus-doped ordered mesoporous carbons (P-OMCs) were homogeneously distributed. The high dechlorination activity was mainly attributed to the homogeneous distribution of Pd/Fe bimetal nanoparticles, which were characterized by transmission electron microscopy (TEM) and scanning electron microscopy/energy dispersive X-ray spectrometry (SEM/EDS) with image mapping. Dechlorination kinetics indicated that the dechlorination rates of 2,4-DCP increased with the increasing of Pd content. The use of P-OMCs as supporting materials to embed enough Pd/Fe bimetal nanoparticles kept the nanoparticles highly active and stable. Besides, solution pH had a significant effect on the dechlorination of 2,4-DCP and the passivation of the Pd/NZVI@P samples. The effects of the number and position of chlorine atoms for different chlorophenols (CPs) on the dechlorination activity were also revealed; the result indicated that the dechlorination of CPs by catalytic reduction preferentially begins from the para-position of the ring, and more chlorine atoms of CPs are favorable for the occurrence of the dechlorination reaction. This study demonstrated that P-OMC is a promising supporting material for the preparation of some effective composite metals for the catalytic dechlorination of CPs.

Amplified and selective detection of manganese peroxidase genes based on enzyme-scaffolded-gold nanoclusters and mesoporous carbon nitride

This work has demonstrated an amplified and selective detection platform using enzyme-scaffolded-gold nanoclusters as signal label, coupling with mesoporous carbon nitride (MCN) and gold nanoparticles (GNPs) modified glassy carbon electrode (GCE). Streptavidin-horseradish peroxidase (SA-HRP) has been integrated with gold nanoclusters (GNCs) as scaffold using a simple, fast and non-toxic method. The mechanisms of enzymatic amplification, redox cycling and signal amplification by this biosensor were discussed in detail. GNCs might perform important roles as electrocatalyst as well as electron transducer in these processes. The concentrations of reagents and the reaction times of these reagents were optimized to improve the analytical performances. Under the optimized condition, the signal response to enzyme-scaffolded-gold nanoclusters catalyzed reaction was linearly related to the natural logarithm of the target nucleic acid concentration in the range from 10(-17)M to 10(-9)M with a correlation coefficient of 0.9946, and the detection limit was 8.0×10(-18)M (S/N=3). Besides, synthesized oligonucleotide as well as Phanerochaete chrysosporium MnP fragments amplified using polymerase chain reaction and digested by restriction endonucleases were tested. Furthermore, this biosensor exhibited good precision, stability, sensitivity, and selectivity, and discriminated satisfactorily against mismatched nucleic acid samples of similar lengths.