Effect of synthesis condition on the structural features of ni-ce bimetallic catalysts supported on functionalized multi-walled carbon nanotubes

In this paper, screening study in regards to preparation of functionalized multi-walled carbon nanotubes (FMWNT)-supported bi-metallic catalyst is discussed. Functional groups such as hydroxyl and carboxylic acid are introduced on multi-walled carbon nanotubes (MWCNT) surface using acid treatment method with the aid of probe-type ultrasonication. It is done by varying the concentration of nitric acid (HNO3) and sulphuric acid (H2SO4), acid volume ratio and treatment duration. Catalysts with different ratios of cerium and nickel nanoparticles which are either loaded inside or outside of MWCNT were prepared via ultrasonic-assisted co-precipitation method (NiCe/CNT). This is done to study the effect of cerium loadings. The characterization of the FMWNT and catalysts are carried out using transmission electron micrographs (TEM), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), Brunauer-Emmett-Teller (BET), X-ray diffraction (XRD), and Raman spectroscopy. The results showed that the treatment in concentrated HNO3/H2SO4 with volume ratio of 3:1 for 8 h was the most suitable condition to generate large amount of surface oxygen group with minimal defects. The observations for each used condition were discussed thoroughly. Decoration of MWCNT with different metal loadings resulted in different distribution and dispersion of metal on nanotubes surface

Effect of reaction time and catalyst feed rate towards carbon nanotubes yields and purity by using rotary reactor

Continuous production of multi-walled carbon nanotubes (MWCNTs) by chemical vapor deposition (CVD) method was investigated in a rotary reactor. The aim of the study was to investigate the effect of catalyst feeding rate and reaction time on the MWCNTs production yield and purity. Bimetallic Co-Mo supported on MgO was used for the growth of MWCNTs and methane gas was used as the carbon precursor. The results indicated that the highest yield of MWCNTs production was attained at the reaction time of 180 min and catalyst feeding rate of 100 mg/min; this sample also had the highest purity (99.16%). SEM and TEM analyses of the synthesized product confirmed that most of the MWCNTs were sinuous and entangled with a uniform diameter. Raman spectroscopy indicated that the as-produced MWCNTs were mostly graphitic with few disordered carbon and impurities. The results highlighted that synthesized MWCNTs were highly pure which eliminates the need for MWCNTs purification process

Optimization of process variables by response surfacemethodology for malachite green dye removal using lime peelactivated carbon

This study investigates the adsorptive removalof malachite green (MG) dye from aqueous solutions usingchemically modified lime-peel-based activated carbon(LPAC). The adsorbent prepared was characterized usingFTIR, SEM, Proximate analysis and BET techniques, re-spectively. Central composite design (CCD) in responsesurface methodology (RSM) was used to optimize the ad-sorption process. The effects of three variables: activationtemperature, activation time and chemical impregnationratio (IR) using KOH and their effects on percentage of dyeremoval and LPAC yield were investigated. Based on CCDdesign, quadratic models and two factor interactions (2FI)were developed correlating the adsorption variables to thetwo responses. Analysis of variance (ANOVA) was used tojudge the adequacy of the model. The optimum conditionsof MG dye removal using LPAC are: activation tem-perature (796°C), activation time (1.0 h) and impregnationratio (2.6), respectively. The percentage of MG dye re-moval obtained was 94.68 % resulting in 17.88 % LPACyield. The percentage of error between predicted and ex-perimental results for the removal of MG dye is 0.4 %.Model prediction was in good agreement with ex-perimental results and LPAC was found to be effective inremoving MG dye from aqueous solutio