Removal of cationic dye by high surface activated carbon prepared from biomass (date pits) by carbonization and activation processes

In this work,we investigated the capacity of activated carbon (AC) to adsorb Methylene Blue (MB) from aqueous solution. AC-H3PO4 and AC-ZnCl2was obtained from date pits via a one-step chemical method using H3PO4 and ZnCl2 as activating agents. The performance of AC was characterized by different analyses techniques: proximate analysis, SEM, XRD and FT- IR and TGA. The experiments results showed that the MB removal increased by increasing each of AC-H3PO4 and AC-ZnCl2 concentration, contact time and temperature. The efficiency of the adsorption tests are evaluated by the Langmuir and Freundlich isotherm models. Equilibrium data fitted well by Freundlich modelwith a maximum of the adsorption capacity of 95 mg/g at 333 K for AC-ZnCl2, However, the adsorption was well adapted to the Langmuir isotherm with a maximum of the adsorption capacity of 125 mg/g at 298 K for AC-H3PO4. The kinetics data was explained by the pseudo second-order model, and the intra-particle diffusion with some other rate controlling steps has been suggested as the adsorption mechanism. The pseudo-second-order model described better the adsorption process. The thermodynamic study suggested that MB adsorption on AC-ZnCl2 was endothermic, spontaneous and non-spontaneous for AC-H3PO4.         

Synthesis and characterization of vanadium pentoxide on different metal oxides by the sol-gel process for application in the conversion of the SO2 to SO3

Sulfuric acid is the largest volume chemical currently produced in the world. Is manufactured by the contact process, it involves three stages: combustion, conversion and absorption. The SO2 conversion reaction is the key step in the process, it uses catalysis. The objective of this work is to synthesize a series of mixed vanadium oxides X% / MO2 with M (Si, Al and Ti) by sol-gel process followed by calcination at 400 ° C, in order to study their reactivity in the catalytic oxidation of SO2 to SO3. Characterization of those materials was carried out by Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM) with energy dispersive X-ray (EDX), X-ray diffraction, thermal analysis (TDA/TGA) and N2 adsorption at 77 K. Their acid-base properties are studied by the decomposition reaction of isopropanol (propan-2-ol). In this work, we have studied the reactivity of the catalysts prepared in the conversion of SO2 to SO3 by an iodometric as dosage which consists in assaying the iode with sodium thiosulfate

The development of a New Process for Phosphate Thickening

In phosphate beneficiation process, thickening is used to concentrate the slurry or sludge in order to increase its solid content and recover the maximum of water. The addition of flocculants helps to form larger particles that can thicken out quickly. However, the high consumption of flocculant in the thickeners increases the cost of the operation. The purpose of this research is to study the effect of flocculant on sedimentation velocities of different particles size in order to develop a new thickening process which ensure the maximum thickening rate and a minimum flocculant consumption.To achieve this goal, initially the impact of flocculant on different size fraction was studied. The objective of this step is to define the cut-size from which the flocculant has no considerable effect on thickening. This granulometric slice can decant by a simple free sedimentation without needing the flocculant. After that, a hydrocyclone was dimensioned and modeled in order to eliminate this granulometric slice which will undergo free sedimentation. This allowed to design a new thickening technology that targets only fine particles overflow of the hydro-cyclone and that require the addition of flocculant. This technology will significantly reduce the flocculant consumption and ensure a better water recovery in the thickening process

Enhanced Biogas Production During Anaerobic Digestion of Steam-pretreated Lignocellulosic Biomass from Williams Cavendish Banana Plants

peer reviewedIn the context of green energy valorisation, this study reports the chemical analysis and improvement of biogas production via anaerobic digestion of treated and untreated agricultural waste lignocellulosic biomass from Williams Cavendish banana plants (WCLB). With a worldwide annual production of 26 million tons of dry matter (DM), large amounts of this waste are abandoned in plantations after fruit harvesting. Steam explosion (SE) and steam cracking (SC) pretreatments were investigated at severity factors of 3.16 and 4.29, respectively, to improve the biogas potential over 135 days under mesophilic conditions. The study revealed a carbon (C)/nitrogen (N) ratio of 27.3, indicating that WCLB has sufficient N content for successful fermentation. The proportions of liquid and solid fractions recovered after SC were 20% and 80%, respectively, whereas SE yielded 17% and 83% liquid and solids, respectively. The neutral sugar content of the studied fractions indicated that glucose and xylose constituted the highest hexose and pentose fractions, respectively, in WCLB. The highest and lowest total biogas potentials were obtained from LFSC (280 mL g-1 of DM) and untreated WCLB (240 mL g-1 of DM), respectively. The methane yield from untreated WCLB and combined solid and liquid fractions from SE and SC were 40, 42, and 51%, respectively, of the theoretical methane potential. The maximum biogas production rate (7.8 mL g-1 d-1) was obtained with SFSC. This study reveals that SC deconstructs WCLB efficiently and thereby greatly enhances methane production