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Bromide ions (Br − ) are associated with toxic by-products that might be produced during the disinfection of drinking water. The removal of Br − from water using roasted date pits (RODPs) and activated carbon was investigated. The percentage removal capacity of Br − was studied under various experimental conditions including solution pH, adsorbent mass and particle size, and initial Br − concentration. Surface characterisation was investigated using scanning electron microscopy (SEM) and Fourier transform infrared (FTIR). SEMs images showed the presence of fine particles (debris) on the surface of the adsorbent solids. The raw date pits (RDPs) surface images showed a marked difference in pore sizes upon roasting, whilst FTIR spectra showed a slight shifting in –O–H, C O, and –C–O stretching in addition to –O–H bending for the RODPs. In addition to the Freundlich and Langmuir isotherm models, the experimental data were fitted to different adsorption kinetic models. It was found that the adsorption of Br − onto RODPs followed pseudo-second order mechanism. Removal rates of around 54% were obtained at lower pH. [ABSTRACT FROM AUTHOR]

Abstract: The treatment of wastes has become one of the most important concerns of modern society to protect the environment. Application of microemulsion modified raw local diatomite (μE-MD) and activated carbon (μE-MAC) as solid extractants for removing inorganic (iron, copper and lead ions) and organic pollutants (soot, oxidations, nitration and sulphation products) from waste lubricants (WL) at a moderate heat have been presented. The results summarised herein are also part of an investigation conducted to evaluate the adsorption removal by taking into consideration the experimental parameters such as initial pollutant concentration and temperature. The raw and modified adsorbents were effective towards all pollutants especially for the inorganic pollutants with high removal percentages (Fe: 34–68%, Cu: ∼65%, Pb: 55–80%) and (oxidation: 7–15%, nitration: 41–46%, sulphation: 5–29%, soot: 42–61%) which indicated the suitability of these new materials for extraction of organic and inorganic pollutants from non-aqueous WL medium. The removal percentages, however, varied from adsorbent to another“. The pHzpc (pH at point of zero charge) was carefully estimated for all adsorbents (raw diatomite (RD), μE-MD, activated carbon (AC), μE-MAC) and found to be (8.6, 7.8, 7.3, 9.1), respectively. The experimental results were also plotted and treated with Langmuir isotherm, uncommon isotherm shapes were obtained. Therefore, it was not fitted to the experimental results which might reflect a complex nature of adsorbing onto the adsorbents. However, this behaviour gave an indication on the complex adsorption mechanisms. Finally, the mode of interaction between the pollutants and the μE-MD and μE-MAC was characterised by comparing the changes in the position and intensity of the surface functional groups using the FTIR technique. Three mechanisms of the adsorption of organic (oxidation, nitration and sulphation) and inorganic (heavy metals) pollutants were possible: (i) adsorption by an electrostatic force of the anionic head group of the surfactant and the positive charge of the organic molecules or the cation metal, (ii) adsorption by tail groups of the surfactant and the hydrophobic character of the organic molecules. The cation heavy metals and the organic compounds have basic characteristics and therefore were expected to interact strongly with the anionic head groups of the surfactants (RCOO−). In the contrary, the cationic heavy metals were not expected to interact by the tail groups of the surfactant where the ionic radii of these ions may explain the differences between every metals removal percentage and (iii) filling the channel (pores) of the RD and the AC by dissolving in the microemulsion micelles. [Copyright &y& Elsevier]

Abstract: The removal of organosulphur compounds (ORS) from diesel fuel is an important aspect of Jordanian''s effort to reduce air pollution by sulphur oxides. The results of this work revealed that activated carbon (AC) has an excellent adsorption for the ORS from non-aqueous diesel medium. Experimental data revealed that percentage removal of the ORS was slightly affected with particle size of the adsorbent, which indicates that elimination of the ORS mainly occurred on the external surface area and the adsorption onto the pores of the adsorbent has a small effect on the entire elimination process. Removal of the ORS by the AC has an endothermic nature where percentage removal values were increased by temperature. The maximum percentage removal value was 72% which was reported at: 2.0g, 300–500μm, 25°C, and 3 days shaking. The experimental results were plotted and treated with Langmuir isotherm, uncommon isotherm shapes were obtained. Therefore, it was not fitted to the experimental results which might reflect a complex nature of adsorbing the ORS onto the AC. However, this behaviour gives an indication on the complex adsorption mechanisms. Finally, the mode of interaction between the ORS and the AC was characterised by comparing the changes in the position and intensity of the surface functional groups using FTIR technique. [Copyright &y& Elsevier]

Abstract: In order to remove the limitations originating from inefficient heat and mass transfer in adsorption refrigeration/heat pump, an innovative arrangement design was proposed. It was equipped with meshed multi-tubular involving activated carbon in a sealed cylindrical adsorber. Related aspects of adsorption refrigeration key parameters were addressed. Working pair, activated carbon–diethyl ether, is used in the above system in order to determine the optimum adsorption refrigeration parameters. In order to estimate the adsorption characteristics and the adsorption capacity of the adsorbent, the adsorption isotherms of that adsorbent, with a specific adsorbate, are carried out. The measured adsorption data were adequately described by the Langmuir equation. The adsorption capacity of the diethyl ether on activated carbon at 26, 35, and 50°C were 0.0159, 0.0220, and 0.0188mmol/g, respectively. Two kinetic adsorption models namely pseudo-first and second order kinetic models were investigated. The thermodynamic parameters, ΔH°, entropy, ΔS°, and Gibbs free energy, ΔG°, of the adsorption process were also obtained from the gas adsorption experiments at various temperatures. These values were −45.84kJ/mol, −88.87J/(molK), and −19.27kJ/mol, respectively. The pseudo-first order model was not applicable in this adsorption system, suggesting that the adsorption process and the rate-limiting step was the pseudo-second order reaction. Therefore, the dominant mechanism might be a chemisorption process between the diethyl ether molecules and the activated carbon surface. The k 2, however, decreased as the initial diethyl ether pressure increased. [Copyright &y& Elsevier]

Abstract: The efficiency of iron coated activated alumina, ferric oxihydroxide and granular activated carbon for the removal of humic substance (HS) from water and wastewater was demonstrated in batch studies. This paper investigated the use of these successful adsorption–adsorbate systems in a continuous flow mode in an effort to obtain the required design and operational data; essential for successful application in water treatment works. The adsorbents were used individually. The influence of the various molecular mass fractions on the adsorption ability of the various systems was considered. Fractionation of humic substances was carried out and low, medium and high molecular mass fractions were produced. Two different column diameters (2.5 and 1cm) were used in the experimental runs. The smaller diameter column was used for experiments dealing with the lower molecular weigh humics as these are very difficult to produce in large enough quantities to carry out continuous adsorption runs in the traditional 2.5cm diameter laboratory adsorption columns. The dissolved organic content (DOC), ultraviolet (UV) absorbance and specific ultraviolet absorbance (SUVA) values were measure and analysed under different operating conditions. Furthermore, the experimental results were modelled using the Thomas model and the empty bed contact time model (EBCT). The Mass Transfer Zone was also analysed for all cases. The results indicated strongly the influence of molecular mass in the adsorption of humic substances. In addition, two distinctive features appear from these results; GAC is able to remove high MM although lacking of mesoporosity (attributed to precipitation and alteration of HS conformation) and β-FeOOH does not show such a high adsorption capacity as previously predicted, attributed to the non-equilibrium state and to the lack of surface under the media compaction. [Copyright &y& Elsevier]