Adsorption Capacity Of Samples Research Articles

Exploring the adsorptive potential of chemically activated Nanoporous carbons derived from invasive goat weed for treatment of hospital wastewater

Nanoporous activated carbons synthesized from goat-weed (Ageratum Conyzoides) using single-step pyrolytic chemical-activation with ZnCl2 and H3PO4 at various ratios. Nano-textural properties of samples assessed through N2 adsorption/desorption, XRD, SEM, and FTIR. ZnCl2 activation led to a high microporosity and maximum surface-area of 1699 m2·g−1 and total pore-volume of 1.23 cm3·g−1 (Zn/biomass ratio 1:1), while H3PO4 activation yielded 866 m2·g−1 and 1.24 cm3·g−1, respectively (P/biomass ratio 1.5:1). The adsorption capacity of samples follows surface-area variations of samples. During treatment of hospital wastewater, ZnCl2-activated carbon removed 90–93 % of pollutants, comparable to commercial carbon, while H3PO4-activated carbon removed 85–88 %. The adsorption mechanism of carbons during interaction with HWW contaminants was discussed to explain variation in removal efficiency.

Carboxylic acid functionalized para-xylene based hypercrosslinked polymer as a novel and high performance adsorbent for heavy metal removal

In this work, hypercrosslinked polymeric adsorbent (HCP) was synthesized from para-Xylene precursor through Friedel-Crafts reaction. Additionally, heavy metal adsorption experiments from a multi component system including lead, cadmium, nickel, and copper ions were conducted. To enhance lead uptake selectivity over other metallic ions, the resulting HCP sample was functionalized through carboxylic acid incorporation into the HCP adsorbent skeleton. The adsorption process modeling was carried out by using Central Composite Design- Response Surface Methodology technique. In addition, the adsorption capability dependency of the resulting samples to the operational condition including temperature from 25 °C to 65 °C, solution pH value from 4 to 10, and solution initial concentration from 20 mg/l to 100 mg/l was investigated. Additionally, process optimization was applied aim to maximize the lead uptake selectivity, the optimal condition including a temperature of 31.8 °C, pH of 5.0, and initial concentration of 82.50 mg/l were obtained for HCP sample, also the optimal condition namely a temperature of 30 °C, pH of 5.5, and initial concentration of 100 mg/l were obtained for modified HCP sample. As a result of isotherm modeling, the Hill model was obtained as the best model, additionally, thermodynamically investigation of the process resulted in spontaneously and physically adsorption of the metallic ions by HCP samples, with respect to Gibbs free energy (ΔG0 < 0) and adsorption process enthalpy (ΔH0 < 20 kJ/mol). Finally, adsorbents regeneration were evaluated and minor losses in the adsorption capacity of samples were yielded after ten cycles.

Removal of Methylene Blue by adsorption onto natural and purified clays: Kinetic and thermodynamic study

The present work explores the optimization of experimental conditions for the adsorption of the organic cationic dye methylene blue (MB) by natural and purified clays. The adsorption capacities of samples were determinate to evaluate the efficiency of the purification process. At first, we performed mineralogical and textural analysis of the clay minerals, namely, smooth clay (SC), rigorous clay (RC) and bentonite clay (BC), using various techniques, particularly, X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and X-ray fluorescence (XRF). The characterizations data showed that SC and RC are mainly composed of smectite associated with kaolinite, illite and chlorite. While BC is considered a mesoporous and swelling clay with smectite as the major component. The cation exchange capacity (CEC) was determinate as a 6.30 meq/100 g, 10.69 meq/100 g and 32.64 meq/100 g for SC, RC and RC natural samples respectively. It was noticed that the CEC as well as the specific surface area increase once the impurities associated with the clay are removed. A preliminary study was carried out to elucidate the influence of different parameters; such as contact time, exchangeable cation, solute concentration, temperature and pH on MB adsorption in aqueous solution by clays. The adsorption equilibrium data were analyzed by the linear and nonlinear forms of the Langmuir and Freundlich isotherm models. The Langmuir isotherm fitted well with the experimental data, and the pseudo-second-order kinetic model represented appropriately the adsorption kinetics of MB dye. Moreover, purified clays showed improved adsorption capacity for MB compared to pristine ones: 147.64; 257.69 and 1383 mg/g versus 128.75; 193.4 and 681.85 mg/g for SC, RC and BC respectively. This is attributed to a suitable specific surface, ion exchange capacity and electrostatic interactions as result of a more adequate texture and composition of our treated clays. The thermodynamic studies reveled negative Gibbs free energy change (ΔG) values (from -6.293 to -18.608 KJ.mol−1), positive enthalpy change (ΔH) values, exceeding 40 kJ/mol and positive entropy change (ΔS) values confirming the spontaneous, endothermic and chemisorption nature of the MB adsorption process. The results show that the tested purified clays are efficient in MB removal and can be used as an alternative to the commercial adsorbents, which are often relatively expensive.

Performance of Sweet Potato’s Leaf-Derived Activated Carbon for Hydrogen Sulphide Removal from Biogas

In this study, sweet potato leaf activated carbon (SpLAC) was prepared by the chemical activation method using KOH and applied as an adsorbent for H2S removal from biogas. The study focused on the understanding of the effect of carbonization temperature (Tc), varying KOH : C activation ratio, flow rate (FR) of biogas, and mass of SpLAC on sample adsorption capacity. The BET analysis was performed for both fresh and spent activated carbons as well as for carbonized samples, which were not activated; also, the activated carbon was characterized by XRF and CHNS techniques. The results showed that removal efficiency (RE) of the SpLAC increased with increase carbonization temperature from 600 to 800°C and the mass of sorbent from 0.4 g to 1.0 g. The optimal test conditions were determined: 1.0 g of sorbent with a KOH : C ratio of 1 : 1, Tc=800°C, and FR=0.02 m3/h which resulted in a sorption capacity of about 3.7 g S/100 g of the SpLAC. Our findings corroborated that H2S removal was contributed not only by the adsorption process with the pore available but also by the presence of iron in the sample that reacted with H2S. Therefore, upon successful H2S sorption, SpLAC is suggested as a viable adsorbent for H2S removal from biogas.

Characterization of graphene oxide supported porous silica for effectively enhancing adsorption of dyes

ABSTRACTThis paper reported the synthesis of graphene oxide (GO)/mesoporous SBA-15 nanocomposite with excellent adsorption properties. The samples were characterized by XRD, FESEM, TEM, FTIR, Raman spectrometer, and surface area analyzer. The adsorption study implied that incorporating GO into SBA-15 frameworks displayed much higher adsorption capacity levels than did pure SBA-15. The composite displayed uniform pore size (6.50 nm), large pore volume (1.035 cm3/g), and high surface area (891 m2/g). The adsorption capacity of samples decreased with increasing sample dosage and adsorption temperature, and increasing initial concentration of dye. The maximum adsorption capacity of the composite for methylene blue was found to be 242 mg/g. The removal efficiency reached 100%. The proposed method was simple and suitable for mass production.

Investigation of Cs(I) and Sr(II) removal using nanoporous bentonite

ABSTRACTBentonites are types of clays made up the dominant constituent of montmorillonite. Four types of nano-porous and nano-structured commercial bentonite clays were studied in detail for their physicochemical and mineralogical properties vs. Cs and Sr adsorption. The instrumental analyses to study samples were X-ray diffraction (XRD), X-ray fluorescence (XRF), Brunauer–Emmett–Teller (BET) surface area measurements, Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and thermogravimetry (TG). The XRF and peaks of XRD patterns at 2θ = 8, 19.9, 35, 55, and 62 clearly indicated that the main component of the bentonite samples was montmorillonite. The BET analysis showed that B1 has the highest specific surface area among the other samples which its single and multiple point BET surface area were equal to 84.85 and 85.94 m2 g−1, respectively. These values represents the amount of montmorillonite and adsorption capacity of samples. The physicochemical, structural and morphological characteristics of different samples were investigated through instrumental analysis. The results of separation processes of Cs(I) and Sr(II) showed 59.75 and 45.5% adsorption capacities for B3 and B2 which were the highest values among the others. The results lead to the conclusion that samples B3 had a good adsorption capacity to remove Cs(I) and Sr(II).

Synthesis of magnetic graphene oxide grafted polymaleicamide dendrimer nanohybrids for adsorption of Pb(II) in aqueous solution

In this paper, using maleic anhydride and ethylenediamine as functional monomers, graphene oxide (GO) loaded magnetic Fe3O4 nanoparticles modified by (3-Aminopropyl) triethoxysilane as support, magnetic graphene oxide grafted polymaleicamide dendrimer (GO/Fe3O4-g-PMAAM) nanohybrids were fabricated by divergent method and magnetic separation technology. The obtained samples were characterized by transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, elementary analyzer and vibrating sample magnetometer. The effects of PMAAM generations, solution pH, Pb(II) initial concentration, temperature and contact time on the adsorption property of the samples for Pb(II) in aqueous solution were studied. The results demonstrated that nitrogen content and adsorption capacity of the as-synthesized samples with amino terminal groups were all higher than their adjacent generations PMAAM with carboxyl terminal groups. Moreover, with increasing generations of PMAAM grafted on to the GO/Fe3O4, the nitrogen content and the adsorption capacity of the samples with the same terminal groups gradually increased. The maximum adsorption capacity of GO/Fe3O4-g-G3.0 for Pb(II) was 181.4mgg−1 at 298K. The rising of temperature was beneficial for the adsorption. The adsorption kinetics had a better agreement with pseudo-second-order equation, and equilibrium data followed the Langmuir model.

Sorption of Lead(II) Ions on Natural Coals and Activated Carbon: Mechanistic, Kinetic, and Thermodynamic Aspects

A sample of activated carbon and two natural coals were studied with respect to the sorption of lead(II) ions from aqueous solutions. Each sample was found to be governed by another immobilization mechanism for lead(II) ions. For activated carbon (AC), interactions of Pb(II) with Cπ electrons of graphene layers were mainly supposed to manifest a strong exothermic effect (−40 kJ mol–1) and a relatively low degree of reversibility (ca. 30%). Both natural coals were practically of the same acidity, ca. 3 mmol g–1. However, only the subbituminous coal (sample H) proved the ion exchange/complexation mechanism as a principal type of lead(II) immobilization. For such adsorption, full reversibility was experimentally confirmed with adsorption heat of −7 kJ mol–1. The adsorption capacity of sample H was found to be the lowest, representing only 0.08 mmol g–1. Contrary to this, oxidative altered bituminous coal (A) confirmed it had the highest sorption ability to lead(II) ions (ca. 0.7 mmol g–1). Its immobilization...

Effect of cobalt and manganese on radionuclides adsorption by modified clay sorbents

The process of decontamination of liquid radioactive wastes, containing Cs-137 and Sr-90, by the sorption method using clay sor­bents, modified by copper and copper-potassium ferrocyanides, and also antimony hydroxide was studied in the paper. The adsorption capacity of samples of the modified clay in the presence of equipment corrosion products, ions of cobalt and manganese, was studied. It was found that the modified clay sorbents are effective in the process of decontamination of liquid radioactive wastes since Cs-137 is re­moved by 99-100 % and Sr-90 - by 70-97 %. Ions of cobalt and man­ganese do not inhibit the adsorption of Cs-137 while the adsorption of strontium is reduced by 5-10 %. Based on the analysis of results of adsorption of Cs-137 in the presence of cobalt, the hypothesis on a significant adsorption capacity of modified clay samples on cobalt was stated.

Silkworms’ feces-based activated carbons as cheap adsorbents for removal of cadmium and methylene blue from aqueous solutions

Activated carbon samples, ACs, were obtained from silkworms’ feces via chemical activation method. Many activating agents including the new ones KCl, CrCl3 and TiCl4 were compared. Acidic and basic oxidic groups in addition to aromatic tertiary and secondary amines have been detected on the surface of produced ACs. Furthermore, microporous solids furnishing high internal specific surface area, ranging between 1000 and 2000m2/g, and total pore volume up to 0.85cm3/g were obtained. TiCl4 resulted in the solid possessing the highest area and pore volume. The obtained solids showed high efficiency in removing methylene blue and cadmium from their aqueous solutions. Adsorption capacity of sample AC/TiCl4 is 461mg/g of MB at pH=10, and 62.6mg/g of Cd2+ at pH=8. The nature of the formed microporous texture and the prevailing surface oxidic groups are the main controlling parameters for the observed high efficiency toward both adsorbates.

Investigation of behaviour of Rh deposited onto polycrystalline SnO 2 by means of TPD, AES and EELS

Rh films deposited onto a SnO 2 polycrystalline substrate were used to study CO adsorption in dependence on the amount of deposited rhodium. The sample purity and composition were investigated by means of Auger electron spectroscopy, the development of a surface electronic structure by electron energy loss spectroscopy. Temperature programmed desorption (TPD) was used to follow the adsorption of CO. The behaviour of Rh deposit stimulated by the annealing and CO adsorption was monitored by a variation of CO desorption energy and an area of the TPD peak. The CO adsorption capacity of sample and stimulation energy of CO desorption decrease if the TPD experiments are repeated. During these experiments the Auger spectra exhibited the presence of a metallic Sn on the surface.

Studies of the adsorbed water layers on solid surfaces by means of the thermal analysis special technique

The paper presents the thermogravimetric studies of water film properties on the solid surfaces using the programmed desorption under the quasi-isothermal conditions. The samples wetted in a different way before the measurements were heated under the suitable quasi-isothermal conditions of temperature increase in the derivatograph using a platinum labyrinth crucible in order to evaporate water films from the surface. During the measurements, the mass loss Q-TG and the differential Q-DTG curves were registered as a function of temperature and/or time which are characterized by the inflections showing individual stages of water desorption from the samples. On the basis of experimental data, the surface wetting mechanism and kinetics of the thermodesorption of water films, discontinuous properties of adsorbed water layers on porous surfaces, adsorption capacity of samples and nature of active sites (e.g. hydroxyl groups) have been presented. It was stated that this method could be successfully applied in the studies of adsorbed water films and surface wetting phenomena.