Preparation of manganese oxides coated porous carbon and its application for lead ion removal.

In this study, porous carbon (PC) was prepared from pyrolysis of sodium carboxymethyl cellulose (CMC) and was further treated with KMnO4 to fabricate manganese oxides coated PC (MnOx/PC). SEM, BET, XPS and FTIR technology were employed to explain their structures. Batch adsorption experiments for Pb(II) were carried out to estimate their adsorption performance. Results showed that manganese oxides coating onto the PC caused the decrease of microporous surface area and microporous volume, while the oxygen content increased greatly. Both PC and MnOx/PC exhibit excellent absorption performance for Pb(II) and their maximum adsorption capacity were 0.6054 and 1.2297 mmol g-1 (about 125.44 and 254.79 mg g-1), respectively. The adsorption process of Pb(II) was quick and pH-dependent. The absorption kinetic and thermodynamic process were fitted well with pseudo-second-order model and Langmuir isotherm model, respectively, suggesting that Pb(II) adsorption onto the sorbents were a chemical process and monolayer adsorption were reached.

Functional reduced graphene oxide-based membranes with selective ion transport channels for zwitterionic ions separation based on the pH gradient.

In this work, we report a method for the fabrication of a functional free-standing graphene membrane (FFGM) with high mechanical strength, enlarged interlayer spacing and ion channels for zwitterionic ions separation. To obtain the FFGM, the anionic dye Eosin Y (EY) was introduced into a graphene oxide (GO) and hydroquinone (HQ) mixture to prepare functional graphene-based membranes on Cu foil using simply a drop-casting method. In comparison with a GO membrane, the molar flux and the mechanical strength of the FFGM were dramatically increased. The FFGM was then equipped on custom-built glass reservoirs for zwitterionic amino acids (AAs) separation based on the inner pH gradient, which was formed by controlling H+ and OH- (in the feed and receiver solution) migration in rGO/GO sheets via an external electric field. With the help of the inner pH gradient and external electric field, AAs could change their charge behaviors. The ionized AAs transport through the FFGM and finally separation was realized.

Synchronous Multi-sits Determination of H2O2 in Vertical Water Based on Phosphor TiO2/SiO2 Nanocomposite.

A promising strategy for trace analysis of hydrogen peroxide (H2O2) in natural water was established based on solid substrate room temperature phosphorimetry. The use of TiO2/SiO2 composite material as a phosphor for H2O2 detection was investigated. TiO2/SiO2 nanoparticle material was manufactured into a test kit for synchronous multilevel sampling test in the water sample reservoir. The proposed TiO2/SiO2 test kit displayed a wide linear response to H2O2 concentrations ranging from 1.0 × 10(-6) to 1.0 × 10(-1) M with a detection limit of 4.6 × 10(-7) M. When the concentration of other species was 100 times of 1.0 × 10(-4) M H2O2, the proposed test kit exhibited good selectivity toward the coexistence of 20 foreign ions. Satisfactory agreement between the proposed kit and spectrophotometric method was obtained, which demonstrated the possibility of its further development into a promising commercial phosphorescence sensor.

Pumpkin-Derived Porous Carbon for Supercapacitors with High Performance.

Pumpkin has been employed for the first time as a renewable, low-cost precursor for the preparation of porous carbon materials with excellent performance. Unlike most other precursors, pumpkin is rich in sugars and starch, and it has advantageous properties for large-scale production. The as-prepared materials adopted a unique morphology that consisted of numerous fused sphere-like carbon grains with a high specific surface area (2968 m(2) g(-1) ), abundant micro and mesopores, and excellent electrochemical properties. The pumpkin-derived activated carbon (PAC) material not only exhibited a high specific capacitance of 419 F g(-1) , but also showed considerable cycling stability, with 93.6 % retention after 10 000 cycles. Moreover, a symmetrical supercapacitor that was based on PAC showed a high energy density of 22.1 W h kg(-1) in aqueous electrolyte. These superior properties demonstrate that PAC holds great promise for applications in electrochemical energy-storage devices.

Poly(methacrylic acid)-grafted chitosan microspheres via surface-initiated ATRP for enhanced removal of Cd(II) ions from aqueous solution.

Cross-linked chitosan (CCS) microspheres tethered with pH-sensitive poly(methacrylic acid) (PMAA) brushes were developed for the efficient removal of Cd(II) ions from aqueous solutions. Functional PMAA brushes containing dense and active carboxyl groups (COOH) were grafted onto the CCS microsphere surface via surface-initiated atom transfer radical polymerization (ATRP). Batch adsorption results showed that solution pH values had a major impact on cadmium adsorption by the PMAA-grafted CCS microspheres with the optimal removal observed above pH 5. The CCS-g-PMAA microsphere was found to achieve the adsorption equilibrium of Cd(II) within 1 h, much faster than about 7 h on the CCS microsphere. At pH 5 and with an initial concentration 0.089-2.49 mmol dm(-3), the maximum adsorption capacity of Cd(II), derived from the Langmuir fitting on the PMAA-grafted microspheres was around 1.3 mmol g(-1). Desorption and adsorption cycle experimental results revealed that the PMAA-grafted CCS microspheres loaded with Cd(II) can be effectively regenerated in a dilute HNO3 solution, and the adsorption capacity remained almost unchanged upon five cycle reuse.

[Characteristics of Pb2+ and Cd2+ sorption in aqueous solution by wheat straw].

Wheat straw was used as biosorbent for lead and cadmium removal from aqueous solution. Especially, the effect of solution pH, contact time and ions concentration on the sorption process was intensively discussed. Result indicated that the metal removal was strongly dependent on solution pH and the sorption capacity increased with the increasing of solution pH in the pH range of 2.0-6.0. The sorption kinetic process fit well with the pseudo-second-order. Langmuir isotherm equation was used to evaluate the sorption capacity of the biomass. The q(max) values for Pb2+ and Cd2+ were 0.15 mmol x g(-1) and 0.11 mmol x g(-1) respectively. After NaOH hydrolated, wheat straw showed higher sorption capacity both for Pb2+ and Cd2+, q(max) values for Pb2+ and Cd2+ reached 0.31 and 0.22 mmol x g(-1) respectively. While the sorption capacity for Pb2+ and Cd2+ on esterified wheat straw decreased greatly. Fourier transform infrared spectroscopy (FTIR) analysis showed that carboxylic groups on the biomass play an important role in Pb2+ and Cd2+ sorption process.

Removal of lead from aqueous solution with native and chemically modified corncobs.

In this study, corncobs biomass was utilized as an adsorbent to remove Pb(II) from aqueous solution. The adsorption behavior of Pb(II) was studied under different conditions, including solution pH, contact time and metal concentration. Ground corncobs were modified with CH(3)OH and NaOH to investigate the effect of chemical modification on Pb(II) binding capacity. Results showed that Pb(II) binding on the biomass is pH-dependent and the kinetics can be well described by the Lagergren-second-order model. The maximum Pb(II) binding capacity q(max) calculated from Langmuir isotherm was 0.0783 mmol/g. After base hydrolysis of the biomass, Pb(II) binding capacity increased from 0.0783 to 0.2095 mmol/g (about 43.4 mg Pb/g). However, Pb(II) binding capacity on the esterified corncobs decreased greatly from 0.0783 to 0.0381 mmol/g. Fourier transform infrared spectroscopy (FTIR) analysis showed that hydroxyl and carboxylic (COO(-)) groups on the biomass play an important role in Pb(II) binding process. The X-ray photoelectron spectroscopy (XPS) data further indicated that lead is adsorbed as Pb(2+) and is attached to oxide groups on the biomass.

Adsorption of cadmium ion from aqueous solution by ground wheat stems.

The adsorption behavior of cadmium on ground wheat stems has been investigated in aqueous solution to understand the physicochemical process involved and to explore the potentiality of wheat stems in wastewater treatment. The results have shown that 0.1032 mmol of cadmium is adsorbed per gram of ground wheat stems. The binding process is strongly affected by solution pH, and the optimum pH is 5.0. The process obeys the Langmuir isotherm model. Blocking of the functional groups on ground wheat stems by chemical modification causes the decrease of the maximum cadmium binding capacity, while increasing the number of the functional groups can enhance the binding capacity of ground wheat stems. Fourier transform infrared spectrometer (FTIR) analysis confirms the chemical modification process and indicates that COO(-) groups on the ground wheat stems are one of the main active groups in cadmium adsorption process. The X-ray photoelectron spectroscopy (XPS) data further indicates that cadmium is adsorbed as Cd(2+) and is attached to O(-) groups on the ground wheat stems.