Suriati Sufian

Effective removal of methylene blue from water using phosphoric acid based geopolymers: synthesis, characterizations and adsorption studies

Phosphoric acid based geopolymers (PAGPs) are a class of geopolymers that are produced by phosphoric acid activation of metakaolin. In this work, two different PAGPs have been synthesized using phosphoric acid to alumina molar ratios of 1 : 1 and 1.2 : 1. The surface profile, chemical composition, micromorphology, and texture properties of the geopolymers were instrumentally determined. Both geopolymers have shown a mesoporous profile with the avg. pore size of 8.6 and 19.4 nm by GP-1M (P : Al = 1 : 1) and GP-2M (P : Al = 1.2 : 1), respectively. Thermogravimetric analysis revealed that these geopolymers were thermally stable up to 800 °C, although the formation of quartz, cristobalite and tridymite was observed in XRD analysis of the samples treated at 800 °C for two hours. The synthesized geopolymers were utilized for the adsorption of methylene blue (MB) by investigating the effect of the amount of adsorbent, pH of the solution and shaking period. The batch kinetics study fitted best into the pseudo second order (PSO) reaction kinetic model. In isotherm modelling studies, the Langmuir isotherm model was best fitted and was used to describe the mechanism of the adsorption. Experimental adsorption capacities (qe) of 2.84 and 3.01 mg g−1 were recorded for GP-1M and GP-2M, respectively. Used adsorbents were successfully regenerated by furnace treatment at 400 °C for two hours, and the regenerated adsorbents presented enhanced adsorption capacities in the range of 4.9–5.07 mg g−1 for five repeat cycles, elucidating that the material is suitable for multiple time use.

Hydrogen Storage of a Fixed Bed of Nanocrystalline Mixed Oxides

Nanocrystalline hydrotalcite derived mixed oxides containing magnesium, cobalt, and aluminum (MCAM) (M(1−x)AlxO(1

Synthesis of Nano-Structured Ni-Co-Al Hydrotalcites and Derived Mixed Oxides

nanostructured hydrotalcite-like compounds that contain nickel, cobalt and aluminum have been synthesized by conventional coprecipitation method without using any surfactants or templating agents. The structure and morphology of the coprecipitated nanohydrotalcites and its derived mixed oxides were characterized by powder X-ray diffraction (XRD), Fourier-transformed Infrared (FTIR) spectroscopy, field-emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM), and nitrogen adsorption-desorption techniques. The results show that the synthesized materials exhibited micro-meso-pore networks. The cobalt-rich calcined hydrotalcites are generally amorphous, having a coral-like morphology whereas nickel-rich hydrotalcites show hexagonal plate-like morphology. The presence of nickel in mixed oxides catalyzed the reduction of Co-Al-O spinels. The Fast Fourier Transform (FFT) analysis of HRTEM revealed the inter planner distances of the crystal of hydrotalcite.

Simultaneous preparation of nano silica and iron oxide from palm oil fuel ash and thermokinetics of template removal

Nanomaterials have potential applications in the fields of catalysis, drug delivery, nanocomposites, and nanofluids. This study suggests a method for simultaneous preparation of nano silica and iron oxide from palm oil fuel ash (POFA). First, POFA was leached out with H2SO4 followed by alkali (NaOH) leaching. Basification (pH = 14) of the filtrate of the first leaching process produced iron oxide, while acidification of the alkali leachate produced nano silica. Addition of polymeric surfactant polyethylene glycol (PEG MW 20000) resulted in deagglomeration of the silica nanoparticles. Silica nanoparticles with sizes in the range of 20–80 nm, surface area of 326 m2 g−1, and pore diameter of 8.2 nm were obtained. Thermokinetic and thermodynamic studies of template (PEG) removal from the silica matrix were performed using the Kissinger and Ozawa methods based on model-free kinetics. The activation energy of PEG decreased from 330 kJ mol−1 to 140 kJ mol−1 when it was used as a template; this result demonstrates the lack of chemical bonding between the surfactant and silica. The findings are supported by the Fourier-transform infrared spectra of the PEG–silica composites.

Characterization of carbon nanofibers treated with thermal nitrogen as a catalyst support using point-of-zero charge analysis

The chemical and physical purification of carbon nanofiber exposes more anchoring sites between meal precursors and carbon surface but thermal N2 gas flow maintains the crystals structure as well as its defect and edge sites, referred to as active sites or anchoring sites. After calcination in nitrogen at 450°C, samples were characterized by Raman spectra X-ray diffraction, as well as thermogravimetric and nitrogen physisorption analyses. Results showed a relatively lower fraction of amorphous carbon to graphite, indicating a greater removal of amorphous carbon. Moreover, the disorder intensity of carbon nanofibers that were treated in N2 flow rate of 1 L/min and 3 hours, called 1Gcom-3h sample, achieved far more defect sites compared with unmodified carbon nanofiber. In addition, the surface areas of mesoporous carbon nanofibers decreased over prolonged residence time. The carbon nanofiber support-metal cation interaction therefore improved the deposition of iron when the point-of-zero charge reading was greater than four.

Effect of Na/Al and Si/Al Ratios on Adhesion Strength of Geopolymers as Coating Material

In this study fly ash based aluminosilicate coatings were formulated and the effect of the Na/Al, Si/Al ratios, and curing time upon adhesion strength of geopolymeric coating was measured using Elcometer 108. Geopolymer gained their maximum adhesion within first three days. After 3 days curing on 60oC resulted into a maximum adhesion strength of 10MPa at Si/Al=3 and Na/Al=1.0. Micro structural analysis and Infra red spectroscopy was used to study the geopolymerisation process. Surface profile of fly ash particles shown that degree of reactivity has a direct relation with their surface roughness.

Application of Experimental Statistical Method in Optimizing Preparation Variables for Cu-Ni/TiO2 Photocatalyst

Cu-Ni/TiO2 was prepared using sol–hydrothermal method. Response surface Method (RSM) including central composite design (CCD) was applied to study the single and combined effects of three primary preparation parameters like water to alkoxide molar ratio (A), acid to alkoxide molar ratio (B), and Cu content (C) on the growth of Cu-Ni doped TiO2 particle size. The particle size range of the photocatalysts was 13−25 nm. Analysis of variance (ANOVA) revealed a second–order polynomial regression model to fit the experimental data in CCD. A comparison between predicted and experimental values has depicted a good agreement amongst them with high coefficient of determination value (R2= 0.98). The 3-D response surface and the contour plots imply a synergistic effect of parameter A, an antagonistic effect of parameter B, and significant interaction between them on the growth of particle sizes more than parameter C and its interactions with other variables. The smaller average sizes of Cu-Ni doped TiO2 particles with higher surface area are helpful to increase the light adsorptive property in hydrogen production studies.

Study on Synthesis and Characterization of Cu-Ni Doped TiO2 by Sol-Gel Hydrothermal

Titania (TiO2) as a semiconductor has been intensively studied during the last decades. Regardless of its superior photocatalytic performance and extensive environmental applications, it has a wide bandgap which lead to a photocatalytic activity only in ultraviolet (UV) irradiation. To shift the activity of TiO2 to visible region, a series of monometallic and bimetallic doped TiO2 was prepared with 10wt% total metals loading. The photocatalysts were synthesized by sol-gel associated via hydrothermal method. The properties of the photocatalysts such as crystal size, surface morphology, total surface area, chemical state of the elements, and bandgap were investigated by using thermogravimetric analysis (TGA), X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), and BrunauerEmmettTeller (BET) measurement. XRD analysis showed that all samples displayed anatase (101) as a main phase of TiO2 with average crystal size between 10-16 nm in a good agreement with the TEM results. The FESEM images show spherical particles less than 20 nm in size. The BET results indicated that all samples are mesoporous. The band gap of Ni-Cu/TiO2 is reduced to 2.65 eV with more absorbance in the visible region compared to those of cu/TiO2 and Ni/TiO2.

Hydrogen Adsorption Capacity Investigation of Ni-Co-Al Mixed Oxides

Micro-mesoporous mixed oxides containing nickel, cobalt and aluminum have been synthesized using conventional coprecipitation method. FESEM and HRTEM analyses demonstrated the flower and hexagonal plate-like nanostructured of mixed oxides. Different mixed oxide formation, homogenous metal dispersion, textural properties were investigated using XRD, ICP-MS and BET (N2 adsorption-desorption) techniques. nanostructured mixed oxides exhibited 2.6 wt% hydrogen adsorption that were studied using temperature programmed reduction-adsorption-desorption (H2-TPR/TPD) and thermogravimetric and differential thermal analysis (TGA-DTA) techniques. Investigation corresponds that morphologies, textural properties and surface energy of mixed oxides are important in hydrogen adsorption.

Effect of heat treatment on the physical properties of bimetallic doped catalyst, Cu-Ni/TiO2

Post heat treatment is critical for the doped semiconductor oxide in order to improve its photocatalytic performance. Thus work had been carried out to understand the effect of different calcination temperature (400, 450 and 500°C) on the physical properties of nanosized Cu-Ni/TiO2Cu-Ni doped TiO2 nanoparticles prepared using a combined method of sol-gel and hydrothermal. The treated samples were characterized using Raman spectroscopy, Brunauer–Emmett–teller (BET) measurement, high resolution transmission electron microscopy (HRTEM), field-emission scanning electron microscopy (FESEM), and diffuse reflectance UV-Vis spectroscopy (DR-UV-Vis). Raman analysis showed that all samples displayed anatase (101) phase of TiO2, which is in good agreement with the TEM results. BET data showed that all prepared Cu-Ni/TiO2 with different calcination temperature are mesoporous. SEM images displayed spherical particles with typical size of about 15 to 20 nm. UV-Vis spectra illustrated that the absorbance edge of all pre...