Influence of different carbon monolith preparation parameters on pesticide adsorption

The capacity of carbon monolith for pesticide removal from water, and the mechanism of pesticide interaction with carbon surface were examined. Different carbon monolith samples were obtained by varying the carbonization and activation parameters. In order to examine the role of surface oxygen groups in pesticide adsorption, carbon monolith surface was functionalized by chemical treatment in HNO3, H2O2 and KOH. The surface properties of the obtained samples were investigated by BET surface area, pore size distribution and temperature-programmed desorption. Adsorption of pesticides from aqueous solution onto activated carbon monolith samples was studied by using five pesticides belonging to different chemical groups (acetamiprid, dimethoate, nicosulfuron, carbofuran and atrazine). Presented results show that higher temperature of carbonization and the amount of activating agent allow obtaining microporous carbon monolith with higher amount of surface functional groups. Adsorption properties of the activated carbon monolith were more readily affected by the amount of the surface functional groups than by specific surface area. Results obtained by carbon monolith functionalisation showed that π-π interactions were the main force for adsorption of pesticides with aromatic structure, while acidic groups play an important role in adsorption of pesticides with no aromatic ring in the chemical structure

Mikrokapilarni reaktor za konverziju CO u CO2

The alcrocapillary carbon supporting carposite platinum catalyst rOd distributed. Palls pores has been Installed into inside chefurnace and tested as oxidation of reactor F6=carbon sonoxide catalytic inlet of the rod was connected carboa sloxide. The valve and outlet was connected-o a tuse supplyinz co-o2 the to she ras. Las chromatogrash tases reselting E=o= chein orde detect product COg has been detested cacalycie Feaocion. The 200-556 0. in with 95% yield the temperature range

Thermal treatment influence on the surface characteristics of the borondoped hydrothermal carbon

Structural and surface characterization of pristine and boron doped carbonized hydrothermal carbons (CHTC) is reported. Boron was introduced into glucose precursor solution with concentration of 0.2% and 1%. Following hydrothermal treatment, samples were carbonized to 1000oC and examined by Raman spectroscopy and temperature programmed desorption. Characterization of obtained samples as material for carbon paste electrode was performed by cyclic voltammetry measurements of the Fe (CN)6 3-/4- redox couple. Structural analysis showed that lower boron content in precursor solution induced structure ordering, while higher amount of boron caused structural disorder of CHTC sample. Boron presence in CHTC samples reduced number of surface active sites for oxygen adsorption and consequently improved their electrochemical response as electrode material for carbon paste electrode

Mathematical modeling of pesticide adsorption on activated hemp fibers

Activated carbon obtained by carbonization and activation of waste hemp fibers was used as an efficient, low-cost sorbent for pesticide removal. Data obtained from batch and continuous process of pesticide adsorption was used for development of the mathematical model that describes the phenomenon of pesticide transport through the porous sorbent matrices. Effective diffusion coefficient and the pesticide concentration profile within the activated hemp fibers, obtained as results of proposed model, give the insight in the mechanism and the rate of adsorption process and pesticide transport through the sorbent. A good agreement between model prediction and the experimental data indicates that the proposed mathematical model can be successfully used for optimization and selection of appropriate adsorption process for pesticide removal

One-step hydrothermal synthesis of photocatalytically active TiO2/carbon composite

TiO2/carbon composite (TiO2/HTC), synthesized by hydrothermal carbonization, was characterized by thermogravimetric analysis, nitrogen adsorption–desorption isotherms and X-ray diffraction. The possibility of using TiO2/HTC as photocatalysts for UV and visible light assisted degradation of methylene blue inaqueous solution was examined. It was found that carbon presence in TiO2/HTC leads to the higher porosity and increase in the share of photocatalytically active anatase phase. Compared to the hydrothermally synthesized TiO2, TiO2/HTC showed the superior photocatalytic activity under UV irradiation. In addition, TiO2/HTC show high recycling ability with degradation ratio of methylene blue higher than 81% after five cycles. Also, TiO2/HTC is expected to be a promising candidate for photocatalytic processes using visible light.Physical chemistry 2016 : 13th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 26-30 September 2016

Characterisation of surface oxygen groups on different carbon materials by the Boehm method and temperature-programmed desorption

The surface characteristics of different carbon materials: activated carbon, carbon felt, glassy carbon and a porous carbon monolith were investigated. The specific surface area was examined by the BET method with N(2) adsorption, the amount and the type of surface oxygen groups by Boehm titration as well as by temperature-programmed desorption (TPD). By comparing the results obtained using BET analysis with those of TPD and the Boehm method, it was found that the number of surface groups was not proportional to the specific surface area. The total amount of oxygen groups, obtained by TPD, is higher than the amount obtained by Boehms method for porous samples. The inconsistencies between these results originate from the fact that the Boehm method is limited to the determination of acidic and basic groups, whereas TPD provides information on the total number of all surface oxygen groups. In addition, the presence of porosity could reduce the solvent-accessible surface in the Boehm method. The TPD profiles of CO evolution showed the presence of a low temperature maximum, below 650 K, which originates from CO(2) reduction on the carbon material surface

The effect of boron doping on the structure and properties of carbonized hydrothermal carbon

Structural and surface characterization of pristine and boron doped carbonized hydrothermal carbons (CHTC) is reported. Boron was introduced into glucose precursor solution with concentration of 0.2% and 1%. Following hydrothermal treatment, samples were carbonized to 1000oC and examined by Raman spectroscopy and temperature programmed desorption. Characterization of obtained samples as material for carbon paste electrode was performed by cyclic voltammetry measurements of the Fe (CN)6 3-/4- redox couple. Structural analysis showed that lower boron content in precursor solution induced structure ordering, while higher amount of boron caused structural disorder of CHTC sample. Boron presence in CHTC samples reduced number of surface active sites for oxygen adsorption and consequently improved their electrochemical response as electrode material for carbon paste electrode

Voltammetric determination of linuron insecticide in methanol using a boron doped, glassy carbon and commercial glassy carbon electrode

This paper presents voltametric studies of the linuron insecticide (3-(3,4-dichlorophenyl)-1methoxy-1-methylureum) on a boron doped glassy carbon (GCB), glassy carbon (GC) prepared in our laboratory and commercial glassy carbon electrode. The method, operated in the differential pulse voltammetric mode, works in the concetracion range from 0.62 to 26.09 mg L-1. We determined a peak potential, Ep, (1.25V), linear range and LOD for linuron in the sulfuric acid as a supporting electrolyte (pH=0.7) for all applied electrodes. GCB shows the broadest linear range and sensitivity. This appears to be the first aplication of a boron doped glassy carbon electrode to the voltammetric determination of linuron insecticide

The in vitro antioxidative and cytotoxic effects of selected Salvia species water extracts

The current paper presents antioxidant and cytotoxic activities and total phenolic and flavonoid content of the selected species of genus Salvia (Lamiaceae) growing wild in Macedonia (S. jurisicii Košanin, S. amplexicaulis Lam., S. ringens Sibth. & Sm.) and Libya (S. fruticosa Mill. and S. lanigera Poir.). Crude water extracts, obtained from aerial parts, were yielded from 6.50 to 14.32%. Total phenolic content was the highest in water extracts of S. amplexicaulis and S. ringens (226.30 and 189.01 mg GAE/g, respectively), while the flavonoids were the most abundant in S. jurisicii extract (32.36 mg QE/g). Antioxidant activities of extracts were measured using DPPH, ABTS and FRAP assays. S. amplexicaulis and S. ringens extracts showed the strongest antioxidant activity, measured using DPPH (14.21 and 23.44 μg/mL, respectively) and ABTS assays (2.91 and 2.42 mg AAE/g, respectively). In FRAP assay, S. amplexicaulis and S. fruticosa extracts exhibited strongest activity (1406.73 and 1191.51 µmol Fe(II)/g). Water extract of S. amplexicaulis and S. ringens performed the strongest cytotoxic activity against K562 cells (151.07 and 173.06 μg/mL, respectively). Based on these findings, it can be concluded that S. amplexicaulis and S. ringens water extracts could be considered as possible source of antioxidant and cytotoxic agents

Glassy carbon and boron doped glassy carbon electrodes for voltammetric determination of linuron herbicide in the selected samples

In this study the application of home-made unmodified (GC) and bulk modified boron doped glassy carbon (GCB) electrodes for the voltammetric determination of the linuron was investigated. The electrodes were synthesized with a moderate temperature treatment (1000A degrees C). Obtained results were compared with the electrochemical determination of the linuron using a commercial glassy carbon electrode (GC-Metrohm). The peak potential (E (p) ) of linuron oxidation in 0.1 mol dm(-3) H2SO4 as electrolyte was similar for all applied electrodes: 1.31, 1.34 and 1.28 V for GCB, GC and GC-Metrohm electrodes, respectively. Potential of linuron oxidation and current density depend on the pH of supporting electrolyte. Applying GCB and GC-Metrohm electrodes the most intensive electrochemical response for linuron was obtained in strongly acidic solution (0.1 mol dm(-3) H2SO4). Applying the boron doped glassy carbon electrode the broadest linear range (0.005-0.1 A mu mol cm(-3)) for the linuron determination was obtained. The results of voltammetric determination of the linuron in spiked water samples showed good correlation between added and found amounts of linuron and also are in good agreement with the results obtained by HPLC-UV method. This appears to be the first application of a boron doped glassy carbon electrode for voltammetric determination of the environmental important compounds