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The aim of work is the use of a cheap adsorbent; sawdust (SD), for the adsorption of anionic dye, acid red57 (AR57), and cationic dye, basic fuchsin (BF). The adsorption of AR57 and BF on SD increased by increasing contact time and adsorbent dosage, while decreased with the increase of temperature and initial dye concentration. The increase in pH decreased the adsorption of AR57 and increased the adsorption of BF. The effective pH, adsorbent dose, and contact time on the AR57 removal efficiency were found to be 3, 0.1 g and 50 min, respectively. While for BF it was found to be 6, 0.2 g and 50 min, respectively. Fitting equilibrium data to Langmuir, Freundlich and Temkin isotherms showed that Freundlich model is the most suitable to describe the acid red57 and basic fuchsin. The kinetic studies indicate that the adsorption of AR57 and BF follows a pseudo-second-order model. The adsorption of both AR57 and BF is spontaneous (ΔG = −3.97, −3.27 kJ/mol) and exothermic (ΔH = −22.9, −8.3 kJ/mol) with negative values of ΔG and ΔH. The negative values of ΔS of both AR57 and BF (ΔS = −64.6, −16.7 J/mol. K) showed that the randomness decreases through the adsorption process. SD is locally available in Egypt - Damietta, as solid residue and it is very cheap, therefore there is no need for its regeneration and reuse because of its nearly free cost and safe disposable. On the other hand, the treated waste liquids reach satisfied limits for reusing in the agriculture of palm trees. [ABSTRACT FROM AUTHOR]

Egypt is facing water shortage due to limitation in the freshwater resources and the increased population growth. Thus, there is a need for developing new water resources such as the expansion in building large-scale reverse osmosis (RO) seawater desalination plants. Oil spill in the marine environment can cause severe fouling problems and make damage to the RO membranes, which increases the operating cost. The current study focuses on oil removal from water using agricultural-based adsorbents to reduce the membrane fouling in the RO systems. Three adsorbents namely: rice husk (RH), sawdust (SD) and sugarcane bagasse (SCB) were tested to remove used motor oil (UMO) and crude oil (CO) from distilled and raw seawater. Activated carbon (AC) was included in the measurements to be used as a reference case to compare with. The oil sorption removal and adsorption capacity were determined experimentally for the four tested adsorbents. The experimental parameters included: initial oil concentration (2-40 g/L), adsorbent dose (2-30 g/L), contact time (5-120 min), agitation time (0-60 min), chemical modification (acid vs. base treatment), water salinity (up to 35 g/L). The effect of the presence of other heavy metals on oil sorption removal and adsorption capacity was also investigated. The characteristics of the adsorbents surface were studied using the Fourier-transform infrared spectroscopy, scanning electron microscopy, and Brunauer-Emmett-Teller analysis. The results demonstrated that the adsorption removal of UMO with higher viscosity is higher than CO and always the RH exhibited the highest adsorption capacity compared to SD and SCB but about 30% less than AC. Precaution should be taken when distilled water is used rather than raw seawater because the difference could reach about 50% but it depends on the type of oil and adsorbing material. Additionally, the oil sorption removal in seawater is about 20% higher in raw seawater compared to distilled water. The oil sorption removal increased with an increase in contact time, adsorbent dosage, agitation time, and salinity, and decrease in initial oil concentration. The effect of presence of metals ions concentration in raw seawater can be neglected with the adsorbent used in the current study. The adsorption isotherm models by Langmuir described the experimental data very well while the pseudo-second-order described the kinetics data very well. The small difference in performance between RH and AC indicates that RH is very promising low-cost adsorbents for oil removal in RO desalination systems. The Gibbs free energy (ΔG) was calculated and the values were negative, indicating that the sorption process was spontaneous. [ABSTRACT FROM AUTHOR]

The recovery of thorium from acidic chloride medium with amine grafted cellulose resins was studied. Mesoporous polymers were modified with ethylenediamine (R1) and diethylenetriamine (R2) after grafting with glycidyl methacrylate. The sorbents obtained were characterized by Fourier transform IR spectroscopy, thermogravimetric analysis, scanning electron microscopy, and surface area measurements. Modified cellulose resins showed high capacity with relative fast kinetics in batch sorption of Th(IV) ions from chloride aqueous solutions. The maximum uptake capacity for Th(IV) ions on R1 and R2 was found to be 80 and 94.6 mg g–1 at pH 3.0 at 25°C within 45 min. The adsorption reaction followed the pseudo-second-order model. The data were fitted well by Langmuir isotherm. The mean adsorption energy calculated using DR isotherm showed that the adsorption followed the chemisorption mechanism. The process was exothermic. The performance of the sorbents in the recovery of Th(IV) ions from a standard rock sample and a granite sample from Gattar area, Egypt, was studied. Desorption was performed using different acids. The maximum Th(IV) desorption, 95 ± 2.8%, was reached with 1 M HNO3. [ABSTRACT FROM AUTHOR]

Highlights: [•] The performance of the kaolin-based zeolites toward Pb2+ removal was studied. [•] Na-Y zeolites prepared from different Egyptian kaolins were used. [•] The zeolitic contents are proportional to the kaolinite contents in raw kaolins. [•] Pb2+ removal and Na+ release are in accordance with the zeolitic contents. [•] Loading capacities of our zeolites are higher than the commonly used adsorbents. [Copyright &y& Elsevier]

A widely distributed mineral, serpentine, obtained from Wadi Ghadir (Eastern Desert in Egypt) was studied as a potential naturally and abundantly available source for the synthesis of an efficient adsorbent for aquatic remediation applications. A novel nanocomposite was synthesized after the exfoliation of the layered structure of serpentine by hydrogen peroxide treatment (serpentine (SP)), followed by decoration with magnetic Fe3O4 nanoparticles (MNP). The goal behind the utilization of the latter phase was to increase the environmental remediation capability and to incorporate magnetic properties at the final adsorbent, toward a better separation after the use. The fabricated composite (MNP/SP) was characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and transmission electron microscopy (TEM). The composite's potential adsorption application toward the removal of two cationic dyes, methylene blue (MB) and malachite green (MG), was investigated. The observed adsorption kinetics was fast, and the highest uptake was observed at pH = 8, with the capacities to reach 162 and 176 mg g−1 for MB and MG, respectively, values significantly higher than various other materials tested against these two cationic dyes. Compared to hydrogen peroxide-treated serpentine, the removal efficiency of the composite was higher by 157 and 127% for MB and MG, respectively. The MB and MG were adsorbed because of the favorable electrostatic interactions between MNP/SP active sites and the cationic dyes. The close value capacities suggest that the difference in chemistry of the two dyes does not affect the interactions, with the later occurring via the dyes' amine functionalities. With increasing ionic strength, the adsorption of the studied basic dyes was slightly decreased, suggesting only partial antagonistic ion effect. The sorbent can be easily regenerated and reused without significant deterioration of its adsorption efficiency, which makes MNP/SP a promising adsorbent for the removal of hazardous pollutants from aquatic environments. [ABSTRACT FROM AUTHOR]