The use of the local common reed (CR) biomass as a novel precursor for activated carbon (AC) production was investigated. Three activated carbons were obtained by impregnation with 50 v/v% H₃PO₄ under different activation temperatures at 400, 450 and 500^oC for 2h. Produced samples were characterized by scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR), and adsorption of N₂ at 77 K. The discharge of phenolic compounds into water-courses is a serious pollution problem which may affect the quality of water supply. Batch adsorption tests were carried out using para-nitrophenol (PNP) as a probe organic pollutant at the temperatures of 20, 40 and 60^oC to investigate the adsorption efficiency of developed carbons. Langmuir and Freundlich isotherm models were studied and the former model showed a satisfactory agreement with experimental data. Adsorption kinetic experiments were determined by pseudo-first order, pseudo-second order, and intraparticle diffusion models. The kinetic removal data of PNP agreed with the pseudo-second order and adsorption process controlled by film diffusion. Overall, the obtained results show that the activation temperature has a significant impact on textural and adsorption characteristics of developed ACs, producing an effective adsorbent for removal of organic pollutants from wastewater.

DOI: http://dx.doi.org/10.5755/j01.erem.59.1.961

Activated carbon was prepared from pre-carbonized petroleum coke. Textural properties were determined from studies of the adsorption of nitrogen at 77 K and the surface chemistry was obtained using the Fourier-transform infrared spectrometer technique and the Boehm titration process. The adsorption of three aromatic compounds, namely phenol (P), p-nitrophenol (PNP) and benzoic acid (BA) onto APC in aqueous solution was studied in a batch system with respect to contact time, pH, initial concentration of solutes and temperature. Active carbon APC obtained was found to possess a high surface area and a predominantly microporous structure; it also had an acidic surface character. The experimental data fitted the pseudo-second-order kinetic model well; also, the intraparticle diffusion was the only controlling process in determining the adsorption of the three pollutants investigated. The adsorption data fit well with the Langmuir and Freundlich models. The uptake of the three pollutants was found to be strongly dependent on the pH value and the temperature of the solution. Most of the experiments were conducted at pH 7; the pH (PZC) of the active carbon under study was 5.0; the surface of the active carbon was negatively charged. The thermodynamic parameters evaluated for APC revealed that the adsorption of P was spontaneous and exothermic in nature, while PNP and BA showed no-spontaneity of the adsorption process and that process was endothermic in nature.

Abstract:The objective of this work is to study the feasibility of two raw materials, calcite and dolomite, as adsorbent for phosphate removal from wastewater. The natural ores were characterized by using both chemical analysis and x-ray diffraction. The results indicate that the calcite sample having the chemical formula CaCO 3 (99 %Ca) and the dolomite is CaAlFeCO 3 (30 %Ca). The effects of pH, contact time and phosphate concentrations on the efficiency of removing were studied. The results indicate that the optimum conditions are : pH = 12, time of contact = 15 min, and the adsorption capacity increased as the phosphate content in the initial solution increased due to the increase of diffusion of the phosphate species. The calcite samples have a higher efficiency than that for dolomite, this may attributed to the higher content of Ca 2+ which acts the more active sites. The mechanism of removing was suggested according to the presence of cations derived from the adsorbent surface and anions loaded on the aqueous medium.

Potassium hydroxide activated carbons were prepared from Egyptian petroleum cokes with different KOH/coke ratios and at different activation temperatures and times. The textural properties were determined by adsorption of nitrogen at −196The adsorption of iodine and methylene blue was also investigated at 30 o C. The surface area and the non-micropore volume increased whereas the micropore volume decreased with the increase of the ratio KOH/coke. Also the surface area and porosity increased with the rise of activation temperature from 500 to 800 o C. Textural parameter considerably increased with the increase of activation time from 1 to 3 h. Further increasing of activation time from 3 to 4 h was associated with a less pronounced increase in textural parameters. The adsorption of iodine shows the same trend of surface area and porosity change exhibited by nitrogen adsorption, with KOH/coke ratio and temperature of activation. Adsorption of methylene blue follows pseudo-first-order kinetics and its equilibrium adsorption follows Langmuir and D-R models.