A new approach to synthesize graphene is oxidizing graphite powder with a mixture of H₂SO₄/H₃PO₄ acids and potassium permanganate. Parameters such as reaction time, reaction temperature, and amount of concentration were varied to study the degree of oxidation of graphite to graphene oxide. Currently, an improved method for the preparation of graphene oxide was the most common one. A mixture of H₂SO₄/H₃PO₄ (9 : 1 volume ratio) instead of only H₂SO₄ resulted in increased hydrophilic and oxidized GO without the emission of toxic gas, which differs from the traditional Hummers’ method. The graphene oxide (GO) was converted to reduced graphene oxide (rGO) by chemical reduction using ascorbic acid as the reducing agent. The GO and rGO were characterized by UV-visible spectroscopy, FTIR spectroscopy, and X-ray diffraction patterns. The result showed that treating graphite powder with potassium permanganate (1 : 9) and a mixture of concentrated H₂SO₄/H₃PO₄ acids at 50°C for 12 hours resulted in a better oxidation degree. The designed synthesis strategy could be easily controlled and is an alternative green approach for the production of graphene oxide and reduced graphene oxide.

Background. Dyes are one of the most hazardous materials in industrial effluents which can cause several health problems in living organisms. The removal of dye from colored effluents has attracted increasing attention in the last decade. In this study, raw, beneficiated, and activated waste ash were evaluated as adsorbents for removal of methylene blue (MB) from aqueous solution by the batch adsorption method. Comprehensive characterization studies were carried out on each bioadsorbent, such as proximate analyses, bulk density, specific surface area, point of zero charge, pH, and Fourier transform infrared (FTIR) spectroscopy (which shows functional groups on adsorbents surface). The effects of pH, adsorbent dosage, initial dye concentration, and contact time were determined in order to know the optimum condition and adsorption potential of the adsorbents. The methylene blue (MB) removal efficiency of raw, beneficiated, and activated bioadsorbents from aqueous solutions was found to be 95.212%, 89.172%, and 84.504%, respectively. It is reported that adsorption efficiency of MB on each adsorbent was quite different due to electrostatic and dispersion interaction between the dye molecules and the surface property of the adsorbents. The obtained results were well fitted with the Freundlich isotherm model, and the adsorption process follows the pseudo-second-order kinetics model for all adsorbents. In fact, the results showed that raw, beneficiated, and activated waste ash bioadsorbents could be employed as effective and economical alternative material in the near future.

The aim of this study was to investigate the adsorption characteristics of malachite green (MG) dye onto the raw (RLAPW) and activated (ALAPW) surface of Lupinus albus seed peel waste prepared via physicochemical activation under alkaline condition as a dye adsorbent. Proximate analysis, surface area (Sears method), point of zero charge (pHzpc), and FTIR analysis were used to characterize the adsorbents. The effects of operational parameters such as pH (4) for ALAPW and pH (6) for RLAPW, adsorbent dose (0.2g), initial dye concentration (30mg/L), contact time (60min), and temperature (298K) were optimized. The experimental data well fitted with the Freundlich adsorption isotherm with the adsorption capacity of 7.3mg/g for activated Lupinus albus seed peel waste (ALAPW) and Sips isotherm for raw Lupinus albus seed peel waste (RLAPW) with the adsorption capacity of 6.6mg/g. The kinetics data well fitted to pseudo-second-order kinetic model for both adsorbents. Thermodynamic study revealed that the bioadsorption process using bioadsorbents was spontaneous and exothermic in nature. Desorption experiment was conducted and showed desorption efficiency at an acidic pH of 2. The results showed that the prepared adsorbents exhibited good adsorption capacity and can be used as an alternative adsorbent for the adsorptive removal of malachite green dyes.

Background : Dyes are one of the most hazardous material in industrial effluents which can cause several health problems in bio-life. The removal of dye from colored effluents has been attracted increasing attention in the recent decay. In this study raw, beneficiated and activated waste ash was evaluated as an adsorbent for removal of methylene blue (MB) from aqueous solution by batch adsorption method. Comprehensive characterization studies were carried out on each bio-adsorbents such as proximate analyses, bulk density, specific surface area, point of zero charge, pH and Fourier-Transform Infrared (FTIR) spectroscopy (which shows functional groups on adsorbents surface). Results : The effects of pH, adsorbent dosage, initial dye concentration, and contact time were determined in order to know the optimum condition and adsorption potential of the adsorbents. The methylene blue (MB) removal efficiency of raw, beneficiated and activated bio-adsorbents from aqueous solutions was recorded to be 95.212%, 89.172%, and 84.504%, respectively. It is reported that adsorption efficiency of MB on each adsorbents was quite different due to electrostatic and dispersion interaction between the dye molecules and the surface property of the adsorbents. The obtained results were well fitted with Freundlich isotherm model and adsorption process follows the pseudo second order kinetics model for both adsorbents. Conclusions : In fact the results showed that raw, beneficiated and activated waste ash bio-adsorbents could be employed as effective and economical alternative material in the near future use. Key words : Bio-adsorption, waste ash, adsorption capacity, surface modification, basic blue dye.

Opals are naturally occurring hydrous silica materials (SiO2*nH2O), and have been largely used in jewelry and as decorative elements in artworks due to their optical properties. In this study, we present some gemological properties, a combined spectroscopic (FAAS, FTIR) and X-ray powder diffraction (XRD) identification of natural and heat treated opals obtained from the main deposits in North Wollo, Ethiopia. The gemological measurements, FTIR and XRD spectra for natural and heat treated samples are nearly identical, FAAS shows clear differences on their color this may be due to the concentration differences of metals. Both of these opals showed spectra and diffraction patterns typical of Opal-CT, with clearly defined patterns and main peaks in the 2θ range of cristobalite and tridymite, called microcrystalline opals.