A quantitive microscale dynamic column breakthrough apparatus for measurement of unary and binary adsorption equilibrium on milligram quantities of adsorbent

A microscale dynamic column breakthrough (μDCB) apparatus with the ability to measure unary and binary adsorption equilibrium on a milligram-scale quantity of adsorbent is described. The μDCB is a low cost system that can be constructed through minor modifications of a commercial gas chromatograph and uses a thermal conductivity detector. The small scale of the apparatus allows for the rapid collection of dynamic column breakthrough experiments. The mass balances for adsorption and desorption experiments were derived along with a description of the blank. The μDCB apparatus was tested with 238.9 mg of zeolite 13X and 180.2 mg of activated carbon with single-component N2/He and CH4/He adsorption and desorption measurements. The measured equilibrium data agreed well with volumetrically collected data. These measurements are both accurate and precise. Multicomponent adsorption was also studied on zeolite 13X and activated carbon for CH4/N2 and CO2/CH4 mixtures. This data was compared with ideal and adsorbed solution theory, extended dual-site Langmuir calculations and the literature.

Study on the treatment of phenol-containing wastewater by doping coal char

The single blending of biomass and S-TiO2 and the mixed modification of coal char were obtained by the method of coking with coal pyrolysis furnace. The adsorption performance of biomass and S-TiO2 was investigated by the adsorption experiment of phenol solution. The results show that under the optimal conditions the best performance of MCC-2 can achieve 94% removal efficiency of phenol. The adsorption efficiency is 20% higher than that reported in the literature, and the adsorption equilibrium time is several times shorter than that reported in the literature. The modified coal char has broad prospects as a substitute for activated carbon in practical application.

Kinetics and Mechanism of Aniline and Chloroanilines Degradation Photocatalyzed by Halloysite-TiO2 and Halloysite-Fe2O3 Nanocomposites

The kinetics of photocatalytic degradation of aniline, 2-chloroaniline, and 2,6-dichloroaniline in the presence of halloysite-TiO2 and halloysite-Fe2O3 nanocomposites, halloysite containing naturally dispersed TiO2, Fe2O3, commercial TiO2, P25, and α-Fe2O3 photocatalysts, were investigated with two approaches: the Langmuir–Hinshelwood and first-order equations. Adsorption equilibrium constants and adsorption enthalpies, photodegradation rate constants, and activation energies for photocatalytic degradation were calculated for all studied amines photodegradation. The photodegradation mechanism was proposed according to organic intermediates identified by mass spectrometry and electrophoresis methods. Based on experimental results, it can be concluded that after 300 min of irradiation, aniline, 2-chloro-, and 2,6-dichloroaniline were completely degraded in the presence of used photocatalysts. Research results allowed us to conclude that higher adsorption capacity and immobilization of TiO2 and Fe2O3 on the halloysite surface in the case of halloysite-TiO2 and halloysite-Fe2O3 nanocomposites significantly increases photocatalytic activity of these materials in comparison to the commercial photocatalyst: TiO2, Fe2O3, and P25.

The study of phosphate ions sorption from silicon dioxide solutions obtained by using acid decomposition of nepheline

The process of sorption of phosphate ion by silicon dioxide obtained by acid decomposition of nepheline is studied. The experimental data were processed using the Freundlich and Langmuir sorption equations, which showed that the sorption process is fairly accurately described by both equations, while the use of the Langmuir monomolecular adsorption equation is preferable in the calculations. The capacity of the adsorption monolayer of the synthesized sample relative to the РО43–-ion and the adsorption equilibrium constant are calculated. Based on the obtained data, various options for sorption treatment of municipal wastewater from РО43--ion to normalized MPC values were evaluated.

Adsorption of phosphate ions from aqueous solutions by layered magnesium and aluminum double hydroxide obtained by solid-phase synthesis

A layered double hydroxide of magnesium and aluminum was obtained by solid-phase synthesis.It was found that it has a predominantly mesoporous structure with cylindrical and wedge-shaped pores, as well as a specific surface area of 50 m2/g. The process of phosphate ion sorption by a synthesized sample is studied. Processing of experimental data on the Freundlich and Langmuir sorption equations showed that the process is described fairly accurately by the Langmuir monomolecular adsorption equation. The capacity of the adsorption monolayer of the synthesized sample with respect to the РО43--ion and the adsorption equilibrium constant are calculated.

Recovery of Waste Polyurethane from E-Waste. Part II. Investigation of the Adsorption Potential for Wastewater Treatment

This study explored the performances of waste polyurethane foam (PUF) derived from the shredding of end-of-life refrigerators as an adsorbent for wastewater treatment. The waste PUF underwent a basic pre-treatment (e.g., sieving and washing) prior the adsorption tests. Three target pollutants were considered: methylene blue, phenol, and mercury. Adsorption batch tests were performed putting in contact waste PUF with aqueous solutions of the three pollutants at a solid/liquid ratio equal to 25 g/L. A commercial activated carbon (AC) was considered for comparison. The contact time necessary to reach the adsorption equilibrium was in the range of 60–140 min for waste PUF, while AC needed about 30 min. The results of the adsorption tests showed a better fit of the Freundlich isotherm model (R2 = 0.93 for all pollutants) compared to the Langmuir model. The adsorption capacity of waste PUF was limited for methylene blue and mercury (Kf = 0.02), and much lower for phenol (Kf = 0.001). The removal efficiency achieved by waste PUF was lower (phenol 12% and methylene blue and mercury 37–38%) compared to AC (64–99%). The preliminary results obtained in this study can support the application of additional pre-treatments aimed to overcome the adsorption limits of the waste PUF, and it could be applied for “rough-cut” wastewater treatment.

COMPARISON OF STINGING NETTLE ADSORPTION PERFORMANCE TOWARDS ANIONIC AND CATIONIC DYES

Stinging nettle was used as lignocellulosic adsorbent for the removal of cationic dye – malachite green (MG), and anionic dye – Congo red (CR), from aqueous solution, without any chemical pretreatment. The adsorption equilibrium data fitted well with the Langmuir model for the adsorption of both dyes, with the calculated maximum adsorption capacity of 270.27 mgg-1 and 172.14 mgg-1 for MG and CR, respectively. The adsorption process was controlled by the pseudo-second-order model in the adsorption of MG and by the pseudo-first-order model in the adsorption of CR. The thermodynamics modelling displayed that the process was spontaneous and endothermic. The π–π electron–donor interaction, hydrogen bonds and pore diffusion may also be effective, besides electrostatic interaction between the adsorbate and the adsorbent in the mechanism of MG and CR uptake.

EFFICIENT ADSORPTION OF Ce (III) ONTO POROUS CELLULOSE/GRAPHENE OXIDE COMPOSITE MICROSPHERES PREPARED IN IONIC LIQUID

A novel adsorbent made of porous cellulose/graphene oxide composite microspheres (PCGCM) was synthesized in [Bmim]Cl ionic liquid. The as-prepared PCGCM was evaluated for the removal of Ce (III) via static adsorption experiments. The results showed that the adsorption equilibrium of Ce (III) onto PCGCM was achieved within 50 min and the adsorption was highly pH dependent. An excellent adsorption capacity as high as 415.1 mg•g-1 was obtained at a pH of 4.9, which was much higher than most adsorbents reported in the literature. The pseudo-second order kinetic model and Langmuir isotherm model were found to fit the adsorption behavior of PCGCM well. The XPS analysis confirmed that the adsorption was based on the ion exchange mechanism. Meanwhile, PCGCM could be regenerated with 1 mol•L-1 HCl for repetitious adsorption of Ce (III). This work provides an attractive approach for the removal of rare earth ions as pollutants.