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Adsorption using activated carbon is found to be a promising technology for the removal of dyes present in wastewater. The carbon prepared from Adenanthera paronina L seeds (APAC5) through chemical impregnation, microwave carbonization, and finally muffle furnace activation found to have a 948 m2/g surface area. The microwave heating generates highly branched activated carbon with fewer surface functional groups. The batch mode adsorption of Basic Orange 21 (BO21) dye onto APAC5 is studied. The maximum quantity of BO21 adsorbed is 49.17 mg/g under batch mode study for 50 mg/lof initial BO21 concentration. The nonlinear form of mathematical expression describes the kinetic and isotherm models better under batch mode analysis. [ABSTRACT FROM AUTHOR]

Carbon nanotubes are prepared along the gravity direction in a spray pyrolysis setup over the silica-supported Fe-Co-Ni catalyst. The silica-supported Fe-Co-Ni catalyst coated over the copper strip is inserted in such a way the coating surface faces downward so that carbon nanotubes can grow along the direction of gravity. Plant-based natural precursor, Pine oil, is used as a carbon source for the preparation of carbon nanotubes by spray pyrolysis method. The effect of precursor flow rate on yield, morphology and structural properties of carbon nanotubes prepared along gravity are discussed. At an optimum flow rate, carbon nanotubes are formed in good yield. The carbon nanotubes synthesized are characterized using appropriate techniques. The scanning electron microscope results show that the synthesized carbon nanotubes are long, straight and well graphitized multi-walled type. The carbon nanotubes diameters are around 50 nm and the average length 20µm. Raman spectroscopy studies revealed that carbon nanotubes are well graphitized multi-walled type with defect-free. A mechanism for the growth of carbon nanotubes along gravity is proposed. Spray pyrolysis of the natural precursor, Pine oil, along with gravity over inversely placed support catalyst material is a promising technique for the growth of long and narrow carbon nanotubes. [ABSTRACT FROM AUTHOR]

A solar active hybrid photocatalyst is synthesized and applied for detoxification and degradation of dye molecules in an aqueous medium. Synthesis of rGO from GO using carica papaya leaf extract and nano-sized CeO2is coated over the rGO to make the hybrid photocatalyst. Prepared hybrids evaluated using SEM, XRD, EDX, IR, surface area (BET) and UV-DRS. Synthesized hybrid is used as photocatalyst for the degradation of Direct Violet 51 (DV 51) dye under both UV and solar irradiations. The surface area of the synthesized composite (CeO2/rGO-HYBD) is 95 m2/g. The Langmuir kinetics for the reaction is also studied. The basic algorithm is used to fit the curves for the LH isotherm; deviations from the experimental values and the reaction order are enumerated for three different hypothetical conditions. [ABSTRACT FROM AUTHOR]

The present studies demonstrate the synthesis of nanocarbon ball-like structures with an approximate size of 50 to 80 nm diameter. A visible light active photocatalyst was achieved by co-doping Y/Fe/TiO2 on the nanocarbon structure. The carbon nanostructure acts as a host material for the Y/Fe/TiO2 composite and its synergetic effect makes the titania to generate electron-hole pair under the irradiation of visible light. The composition and morphological structures were studied using XRD and FESEM. From UV-DRS analysis, the calculated optical band gap for the composite catalyst is 2.73 eV. The photo-induced fragmentation of the Rhodamine-B dye was studied and the actual kinetics was evaluated using linear and non-linear methods. The non-linear kinetic model found more appropriate to describe the kinetics and the linear model has some limitations. [ABSTRACT FROM AUTHOR]

A novel non-conventional activated carbon with good surface characteristics was synthesized using Wrightia tinctoria fruits as a precursor material under two stage microwave heating. The synthesized activated carbon has a BET surface area of 911m2/g. The adsorptive capability of the prepared adsorbent (WAC) was tried using Ni(II) as an adsorbate. The adsorbent WAC removes 36.64 mg of Ni(II) per gram of adsorbent at an initial nickel concentration of 50 mg/L. On increasing the solution temperature from 30 to 45°C, the amount Ni(II) adsorbed by WAC increases from 24.17 to 25.81 mg/g, which substantiates the endothermic nature of adsorption. Freundlich model describes the adsorption with good correlation coefficient of 0.9971 < r2 < 0.9997, indicating the heterogeneous nature on the adsorbent surface. Thermodynamic studies indicates the endothermic (positive ΔH°), spontaneous (negative ΔG°) nature as well as the increased randomness (positive ΔS°) at the solid liquid interface. [ABSTRACT FROM AUTHOR]