Adsorption of dyes onto carbonaceous materials produced from coffee grounds by microwave treatment

Organic wastes have been burned for reclamation. However, they have to be recycled and reused for industrial sustainable development. Carbonaceous materials were produced from coffee grounds by microwave treatment. There are many phenolic hydroxyl and carboxyl groups on the surface of carbonaceous materials. The base consumption of the carbonaceous materials was larger than that of the commercially activated carbon. The carbonaceous materials produced from coffee grounds were applied to the adsorbates for the removal of basic dyes (methylene blue and gentian violet) in wastewater. This result indicated that the adsorption of dyes depended upon the surface polar groups on the carbonaceous materials. Moreover, the Freundlich constants of isotherms for the adsorption of methylene blue and gentian violet onto the carbonaceous materials produced from coffee grounds were greater than those for adsorption onto activated carbon or ceramic activated carbon. The interaction was greatest between the surface or porosity of the carbonaceous materials and methylene blue and gentian violet. The microwave treatment would be useful for the carbonization of organic wastes to save energy.     

Adsorption of fluoride ions onto carbonaceous materials

The characteristics of fluoride ion adsorption onto carbonaceous materials were derived as adsorption isotherms at different temperatures and in different pH solutions. The fluoride ion was adsorbed into pores in carbonaceous materials produced from wood; the larger the specific surface area, the more fluoride ions adsorbed. Bone char was the most effective adsorbent. The composition of bone char includes calcium phosphate, calcium carbonate, and so on. This suggests that the phosphate ion in bone char was exchanged with a fluoride ion. Moreover, the mechanism of fluoride ion adsorption onto bone char is clearly chemical in nature because the amount of fluoride ion adsorbed onto bone char increased with increasing temperature and decreasing pH. The amount of fluoride ion adsorbed onto bone char was also shown to depend on the concentration of sodium chloride in solution because of the "salting-out" effect. The adsorption of fluoride ion onto bone char is endothermic. Bone char can be utilized to remove fluoride ions from drinking water.     

Characterization of water adsorption onto carbonaceous materials produced from food wastes

The recycling of organic wastes has become very important and the development of technology for recycling organic wastes needs to sustain industrial development. In this study, techniques for producing carbonaceous materials from organic wastes are described and water adsorption is characterized. The organic wastes used are coffee grounds and oolong tea leaves carbonized at 673 to 1073 K. The iodine adsorption capacity of the carbonaceous materials increased with increased carbonization temperature. The amount of water adsorbed onto the carbonization materials produced from oolong tea leaves at 873 K for 2 h was the highest. The Freundlich constant 1/n and the differential heat of adsorption of the carbonaceous materials produced from oolong tea leaves were greater than that of the carbonaceous materials produced from coffee grounds. The ability to humidity control can be estimated by the difference between the amount of water adsorbed relative pressure 0.90 and that at relative pressure 0.55. The ability to humidity control was the greatest for the carbonaceous materials produced from the oolong tea leaves at 873 K for 2 h and did not depend upon the adsorption temperature. These results indicated that the carbonaceous materials produced from oolong tea leaves at 873 K for 2 h could have more humidity control.     

Adsorption of organic compounds onto activated carbons from recycled vegetables biomass

The removal of organic species from aqueous solution by activated carbons is investigated. The latter ones are prepared from olive husks and almond shells. A wide range of surface area values are obtained varying temperature and duration of both carbonization and activation steps. The adsorption isotherm of phenol, catechol and 2,6-dichlorophenol involving the activated carbons prepared are obtained at 25 degrees C. The corresponding behavior is quantitatively correlated using classical isotherm, whose parameters are estimated by fitting the equilibrium data. A two component isotherm (phenol/2,6-dichlorophenol) is determined in order to test activated carbon behavior during competitive adsorption.     

Adsorption of humic acid onto carbonaceous surfaces: atomic force microscopy study

The adsorption of humic acid (HA) onto highly ordered pyrolytic graphite (HOPG) surfaces at different concentrations has been studied by atomic force microscopy. When HA concentration was increased from 10 to 1,000 mg/L, HA can sequentially form spherical particles, layered structures, and connected blocks on HOPG surfaces. The findings of the layer structures and small amount of fine chains have been verified and discussed. When HA was acidified by addition of acetic acid, it changed into small rigid particles. These results indicated that HA can be considered as supramolecular associations of self-assembling heterogeneous and relatively small molecules, and a small amount of polymers. The present results are important for understanding HA molecular structures and their adsorption characteristic on carbonaceous surfaces.     

Synthesis of porous carbon materials from wood waste pre-treated with water

The possibility of producing porous carbon materials from birch sawdust exposed to natural decomposition in water was demonstrated. It was established that the carbon material carbonized at 800°C was of a specific surface area nearly by one order of magnitude higher than that of a product produced using ordinary sawdust under the same conditions. It was suggested that developing porous structure of the carbon product was due to structural changes in wood mainly by reducing an amount of α-cellulose and its interaction with water.     

Adsorption characteristics of metal-EDTA complexes onto hydrous oxides

The adsorption characteristics of a variety of metal-EDTA complexes onto hydrous oxides, principally aluminum oxide (γ-Al₂O₃), were examined in aqueous solution. Adsorption of these complexes increased with increasing proton concentration due to the formation of surface complexes between EDTA and the surface hydroxo groups, specifically the AlOH₂⁺ surface groups. The pH-dependent adsorptive behavior and the magnitude of adsorption of the “free” EDTA species were similar to those of the metal complexes. The results also showed that the adsorption of “free” EDTA was exothermic, while the adsorption of Ni(II)-EDTA complexes was endothermic in the lower pH region (3.5) and exothermic at higher pH values (6.0). This implied that the surface preferred the NiHEDTA⁻¹ species rather than the NiEDTA⁻² species. Specific adsorption of the metal complexes was evidenced by the charge reversal exhibited by the γ-Al₂O₃ particles at the highest surface loadings. A quantitative model was formulated based on the pH-dependent speciation of the oxide surface, speciation of the metal complexes in solution, and ζ potential measurements. This model proved valid over a wide range of pH (3–10) and for both high (>50% coverage) and low (<10% coverage) surface loadings.     

Adsorption of pyridine onto the metal organic framework MIL-101

The adsorption of pyridine onto the metal organic framework MIL-101 was investigated by experimental and theoretical methods. The amount of pyridine adsorbed on MIL-101 was extraordinarily large at 20 °C, corresponding to about 950 mg/g of dried MIL-101 and approximately half of the voids being filled. Most of the pyridine that had filled the voids was rapidly removed by evacuation at room temperature, but some of the pyridine was so strongly adsorbed that it was retained even under evacuation at 150 °C. Although IR spectra of the adsorbed pyridine indicated the adsorption of pyridine as pyridinium ions and coordinated pyridine at low temperatures, increasing the adsorption temperature induced partial cleavage of the pyridine rings. The high stabilization energy of pyridine on the coordinative unsaturated sites (CUS) of MIL-101, obtained by theoretical calculation, -103 kJ/mol, supported the strong adsorption of pyridine on the CUS.     

Structural and sorption characteristics of carbon adsorbents from waste formed in wood processing

The structural and sorption characteristics of microporous sorbents from industrial lignin with respect to some toxic substances, Pb²⁺, Cd²⁺, Cu²⁺, and NH⁺ ₄ ions, and also the possibility of accumulation of methane on these carbons were studied. Simple procedures for modification of the carbon surface to improve the sorption power of the carbons were suggested.     

Adsorption of Sb(V) from radioactive organic waste solutions on different adsorbents

The adsorption of radioantimony (¹²²Sb and¹²⁴Sb) on pyrolysis residue, bentonite and fly ash from its solutions in benzene, toluene and xylene was investigated. The radioactivity of the isotopes was measured in the organic solution above the adsorbents as a function of time. After 24 h, the sequence of uptake of Sb(V) in benzene and toluene is: pyrolysis residue>bentonite>fly ash, while in xylene it is bentonite>pyrolysis residue>fly ash. The maximum lg k_D value was 3.37 for the toluene-pyrolysis residue system. Desorption of Sb(V) from the loaded material was studied using both tap water and 1M HCl. The latter has more desorption power, evidently, due to hydrolysis and production of insoluble species in the neutral medium.     

Adsorption of organic compounds onto polyelectrolyte immobilized-surfactant aggregates on cellulosic fibers

The adsorption of anionic surfactants with different hydrophobic chain lengths onto cellulose fibers pretreated with a cationic polyelectrolyte has been investigated. Five steps are involved in the adsorption process, which was ascribed to the formation of monolayer and bilayer surfactant aggregates. Electrostatic interaction between the residual surface charges followed by hydrophobic interaction among the alkyl chains are considered the main factors in the adsorption process. The adsorption of the anionic surfactant was found to greatly enhance the retention of organic compounds onto the polyelectrolyte-treated cellulose. The coadsorption phenomenon, which was dependent on the saturation level of the adsorbed surfactant, has been explained in terms of the accumulation of the organic solute on the hydrophobic core generated by the adsorbed layer.     

Effect of wood flour content on surface properties of 3D printed materials produced from wood flour/PLA filament

Amount of wood flour was gradually increased from 0 to 50?wt% in the production of polylactic acid (PLA) based filaments with 1.75?mm diameter using twin screw extruder. Surface roughness and wettability were measured of the specimens. Surface roughness of the specimens significantly increased with incorporation of wood flour into PLA filament. Wettability of the specimens significantly decreased with increasing wood flour content. This was mainly attributed to the higher surface free energy of PLA than the beech wood. Contact angle values of the 3D printed wood/PLA specimens having wood flour content up to 30?wt% were less than 90°.     

Adsorption characteristics of organosilica based mesoporous materials

Hybrid organosilica mesoporous materials with pores of ordered three-dimensional hexagonal structure were prepared by the hydrolysis and co-condensation of 1,2-bis(triethoxysilyl)ethane with various concentrations of a surfactant as structure directing agents. The materials had high pore volume of 1-1.5 mL/g and high surface area from 1057 to 1445 m(2)/g. Adsorption measurement and adsorption calorimetry revealed that the prepared materials exhibited high hydrophobicity and high affinity toward nonpolar organic vapor such as n-hexane. The dynamic adsorption properties of the materials for n-hexane in the presence of water vapor showed that these hybrid organosilica materials preferentially adsorbed n-hexane vapor and were stable in the presence of water compared to the siliceous MCM48.     

Chemical properties of the surface of nanofibrous carbonaceous materials produced by catalytic methane decomposition

The chemical behavior of nanofibrous carbonaceous materials prepared by the catalytic decomposition of methane was studied by IR spectroscopy, X-ray photoelectron spectroscopy, and titration. Initial carbon was shown to be virtually devoid of functional groups on its surface. Treatment of carbonaceous samples with alkali, ammonia, or nitric acid modified the surface of carbon and increased the number of functional groups.     

Adsorption of dissolved organic compounds on porous polymeric materials

The structure and the adsorption characteristics of porous polymeric materials were studied by the methods of X-ray diffraction analysis and adsorption from solutions. The values of the adsorption capacity, the mean pore size, standard decrease in the molar free energy of adsorption, internal diffusion coefficients of nitrobenzene and p-nitroaniline in the primary and secondary porous structures were calculated.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 21, No. 3, pp. 378–381, May–June, 1985.     

纳米TiO-2对模型病毒-f2噬菌体的吸附特性

为了提高饮用水处理系统对病毒的去除效果,本研究采用静态实验,研究纳米TiO2对模型病毒—f2噬菌体的吸附去除特性,系统考察TiO2投加浓度、病毒浓度、温度及pH值等因素对吸附效果的影响.实验结果表明：f2噬菌体在纳米TiO2表面的吸附符合准二级吸附动力学模型,遵循化学吸附机理,颗粒内扩散为该吸附过程中的速率控制步骤,但不是唯一控制步骤;纳米TiO2对f2噬菌体的吸附符合Freundlich等温吸附模型（qe=27.4Ce1.24）,属于多层吸附类型;在20~40℃范围内,温度对纳米TiO2的吸附性能影响不大,而酸性条件下更有利于纳米TiO2对f2噬菌体的吸附.     

Adsorption characteristics of tributyltin on municipal solid waste compost

The sorption behaviour of tributyltin (TBT) from reconstituted seawater onto municipal solid waste (MSW) compost was investigated to give first insights into the equilibrium and kinetic behaviour of this process. The rate of adsorption, the influence of pH, and the adsorbate hydrophobicity on the partitioning process were investigated. Adsorption kinetics indicated an initial fast rate of adsorption of TBT followed by a slower rate. The similarity of Freundlich sorption and desorption coefficients for TBT showed that the sorption process is also reversible, similar to that for the adsorption of TBT onto marine sediments. It was found that the adsorption capacity for TBT onto compost was highest at pH 6.7, and for other organotins it increased with increasing adsorbate hydrophobicity, following the trend tripropyltin < TBT < tripentyltin. The use of washed MSW compost as a sorbent for the purification of TBT‐contaminated wash waters as generated in large quantities during hull cleaning in dry docks is suggested as a mitigatory measure against pollution of the marine environment by TBT. Calculations suggest that modest amounts of compost will likely be required to treat the contaminated wastewaters generated from the Malta dry docks if a multiple batch system is adopted. Copyright © 2005 John Wiley & Sons, Ltd.     

Adsorption of cationic surfactants and subsequent adsolubilization of organic compounds onto cellulose fibers

Cationic surfactants with different hydrophobic chain length were adsorbed onto cellulose fibers in an aqueous medium. The adsorption isotherms exhibited three characteristic regions which were interpreted in terms of the mode of aggregation of the surfactant molecules at the solid–liquid interface. The hydrophobic layers were used as a reservoir to trap various slightly water soluble organic molecules. A quantitative study of these phenomena suggested typical partition behavior of the organic solutes between the aqueous phase and the surfactant layer. The surfactant chain length (from C12 to C18) was shown to play an important role in terms of the capacity to retain the organic solute and the capacity increased with the number of carbon atoms.     

Adsorption of CTAB onto perlite samples from aqueous solutions

In this study, the adsorption properties of unexpanded and expanded perlite samples in aqueous cetyltrimethylammonium bromide (CTAB) solutions were investigated as a function of ionic strength, pH, and temperature. It was found that the amount of cetyltrimethylammonium bromide adsorbed onto unexpanded perlite was greater than that onto expanded perlite. For both perlite samples, the sorption capacity increased with increasing ionic strength and pH and decreasing temperature. Experimental data were analyzed by Langmuir and Freundlich isotherms and it was found that the experimental data were correlated reasonably well by the Freundlich adsorption isotherm. Furthermore, the isotherm parameters (KF and n) were also calculated. The adsorption enthalpy was determined from experimental data at different temperatures. Results have shown that the interaction between the perlite surface and CTAB is a physical interaction, and the adsorption process is an exothermic one.     

Catalytic pyrolysis of waste wood chip over mesoporous materials using Py-GC/MS

Research on Chemical Intermediates - Pyrolysis Gas Chromatography/Mass Spectroscopy (Py-GC/MS) was used to investigate the catalytic pyrolysis of waste wood chip. Two different mesoporous...