Research On the Fractal Dimensions of the Organic-Rich Shale Pores Via Different Models

Fractal dimension can be used to the pore surface characterize. For pore structures in different sizes, the calculation models of fractal theory should be distinguished due to the different principles of the gas adsorption experiments. To further study the adaptability of the fractal model for gas adsorption experimental data, the author collected shale samples of Longmaxi formation from Well JY1, then CO2 and N2 adsorption provided the PSD curves. In addition, the fractal dimensions of micropore and mesopore were calculated by the Jaroniec fractal model and Frenkel–Halsey–Hill (FHH) fractal model respectively. The research shows that the Jaroniec model may be suitable to calculate CO2 adsorption data and could characterize the fractal dimension of micropore, while the FHH model may be suitable to calculate N2 adsorption data in the high relative pressure region. It suggests that the micropore and mesopore could have different dimensions and the evaluation of the structure in shale pores should consider both of them.

Determination of rice husk activated Carbon capacity in adsorption of Cu Metal from Sasirangan liquid waste based on isotherm model

The process of manufacturing Sasirangan - a traditional fabric of South Kalimantan - has an impact that affects environmental pollution, namely the dyeing process of the fabric. The synthetic dyes used contain heavy metals and one of those toxic metals is copper (Cu). This study aims to determine the adsorption capacity of rice husk activated carbon adsorbent by adjusting the adsorption pattern based on isotherm models as the treatment to sasirangan liquid waste. The method consists of three stages: preparation of adsorbent by carbonization process, chemical and physical activation, then continued by adsorption process of Cu metal with carbon from rice husks with variations of adsorbent dose (2, 4, and 6 grams). This treatment was conducted by batch process. In this reseach, the adsorption capacity of rice husk adsorbent towards heavy metal Cu in sasirangan liquid waste was determined from the equilibrium state with the Langmuir isotherm equation and Freundlich isotherm equation. Based on isothermal studies of adsorption data, the correlation coefficient values obtained from the isotherm model approaches are: for dose of 2 grams adsorbent, Langmuir R2 = 0.9991 and Freundlich R2 = 0.9981; for dose of 4 grams adsorbent, Langmuir R2 = 0.9992 and Freundlich R2 = 0.9989; for dose of 6 grams adsorbent, Langmuir R2 = 0.9990 and Freundlich R2 = 0.9986. The results of investigation indicate that adsorption data correlated well with Langmuir isotherm model.

Adsorption of Flagyl on Prepared Ash from Rice Husk

In recent years, it has been evident that searching for alternative methods with low-price and eco-friendly features that produce high-quality adsorbents is in high demand. In the present work, Rice husk from Iraqi rice named (Amber) had been used as the primary source to produce rice husk ash (RHA) for the removal of the antibiotic metronidazole (Flagyl) from water. After optimum drying of rice husk, rice husk ash (RHA) was obtained at 600 °C using an electric oven. RHA has been investigated for properties using X-ray diffraction (XRD), porosity, and surface area (SA). The experimental work adsorption data were optimized to evaluate Langmuir and Freundlich constants. The thermodynamic parameters likely a change in Gipp's energy (ΔG), enthalpy (ΔH), and entropy (ΔS). The impacts of increasing temperature on adsorption capacity were investigated, and the results indicate that the pseudo-second-order kinetics model could be presented the dynamic adsorption data that it has. The resultant values for the heat of adsorption and the free energy indicated that adsorption of Flagyl is preferred at low temperatures.

Anti-microbial and methylene blue dye adsorption properties of cotton fabrics modified with TiO2, Fe, Ag-doped TiO2, and graphene oxide nanomaterials

Nanoparticle materials have received increasing attention in the functional modification of textiles. In this work, pure TiO2, Ag-doped TiO2, Fe-doped TiO2, and graphene oxide nanoparticles were used to impart the anti-bacterial and adsorptive properties of nanoparticles to cotton fabric. The treated fabric materials were investigated by X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy. The obtained treated fabrics were used as adsorbents for the removal of methylene blue from aqueous solution. The functionalized cotton fabrics were tested for their anti-microbial capability against Escherichia coli, Bacillus cereus, and Candida albicans. All the functionalized fabrics have higher anti-microbial activity compared to untreated cotton, especially the fabrics containing silver and Fe-doped TiO2. The optimum conditions of the adsorption process are determined via the study of the effect of the initial concentration of dye, pH, and contact time on the removal efficiency. Langmuir, Freundlich, and Temkin isotherms are applied for the equilibrium adsorption data. GO-Cot and Ag-Ti@GO-Cot samples showed the highest adsorption removal activity. The linear correlation coefficient ( R2) showed that the Temkin model well fitted the data of adsorption in the GO-Cot sample. The analysis of experimental data with different kinetic models showed that the pseudo-second-order kinetic model well fitted the adsorption data better than the other kinetic models of the pseudo-first-order, Elovich, and intra-particle diffusion.

Development of Pectin-Based Aerogels with Several Excellent Properties for the Adsorption of Pb2+

Traditional aerogels lack specific functional groups for the adsorption of Pb2+, which results in a low adsorption capacity and limits the application scope. Novel porous pectin-based aerogels (PPEAs) were prepared by incorporating polyethylenimine (PEI) using ethylene glycol diglycidyl ether (EGDE) as a cross-linker for the removal of Pb2+ from water. The cross-linking mechanism, morphology, mechanical strength, thermal stability, adsorption properties, and mechanism of the aerogels were investigated. The aerogels possessed several desirable features, such as a large maximum Pb2+ adsorption capacity (373.7 mg/g, tested at pH 5.0), ultralight (as low as 63.4 mg/cm3), high mechanical strength (stress above 0.24 MPa at 50% strain), and easy recyclability. Meanwhile, the equilibrium adsorption data was well described by the Langmuir–Freundlich (Sips) model and the kinetic adsorption process was well fitted using the pseudo-second-order model. The donor groups, such as -NH2, and oxygen-containing functional groups were responsible for the Pb2+ adsorption, which was confirmed by the FTIR and XPS analysis. The excellent characteristics mean that PPEAs are highly effective adsorbents in the remediation of lead-containing wastewater.

Nonlinear regression for analysis of the uptake of KMnO4 from aqueous solutions onto natural marl

The present work aims to evaluate the performance of raw marl collected from the region of Oum El Bouaghi on the elimination of KMnO4 from aqueous solution. The adsorption capacities were studied using the batch technique as a function of pH, initial concentration and temperature. The maximum adsorption for KMnO4 was found to be 83.517% at pH 3.0. When the pH is low (pH<3.0), the uptake of KMnO4 occurs with an electrostatic attraction between the MnO4-ions and the surface proton groups, while at pH ≥3.0-8.0, the formation of complexes with the surface functional groups during the adsorption process and/or cation exchange are responsible for retention of Mn(II) ions onto marl. Experimental adsorption data were modeled with different nonlinear isotherms and kinetic models. Furthermore, statistical errors (SSE, SD, ARE, χ 2, R2 and R2 adj) were calculated to choose the suitable model. Langmuir isotherm was found to be best for fitting the experimental data. The calculated thermodynamic parameters indicated that adsorption process was physical, spontaneous and endothermic in nature. From this work, it was concluded that the natural marl can be used for effective elimination of KMnO4 from aqueous solution and wastewater.

Removal of mercury ion from wastewater using natural zeolite: effect of humic acid to adsorption isotherm

As Indonesia possessed a considerable amount of gold deposit, many golds mining activities, including the small-scale one, is commonly found. A simple mining technique (amalgamation) that utilizes mercury (Hg) will generate mercury-containing wastewater. One of the prospective Hg removal methods from wastewater is adsorption. In addition, it is also possible that metal contained in the wastewater interacts with other substances, such as humic acid. This experiment was aimed to examine the adsorption process of Hg2+ ions in the wastewater using natural zeolite. The effect of the presence of humic acid, which might be found in sewage, toward the adsorption capacity of Hg2+ onto natural zeolite was investigated. The natural zeolite, which contained several types of minerals, was obtained from Klaten, Central Java. The experiment was conducted using ten mg/L HgCl2 as the initial concentration and ten mg/L humic acids. A comprehensive study that includes isotherm and the kinetic study was carried out. Experimental results showed that the presence of humic acid was found to reduce the capacity of Hg2+ adsorption on natural zeolite. Freundlich isotherm model was found to be more suitable to represent equilibrium adsorption data. Kinetic examination revealed that the pseudo-second-order model was able to produce a better agreement with experimental data.

High Removal Efficiency of Diatomite-Based X Zeolite for Cu2+ and Zn2+

Diatomite-based X zeolite was obtained and its crystallinity, morphology, and interface properties were investigated by XRD, BET, SEM, EDS, and XRF. The obtained X zeolite possessed a unique meso-microporous structure and showed good ion exchange properties for Cu2+ and Zn2+. The pseudo-second-order model and Langmuir isotherm model can best describe the adsorption kinetics and isotherms of Cu2+ and Zn2+, respectively. The maximal adsorption capacities of X zeolite for Cu2+ and Zn2+ were 146 and 195 mg/g at 323 K, respectively. Meanwhile, the adsorption process for Cu2+ and Zn2+ were chemical adsorption and ion exchange, respectively. Furthermore, the adsorption data turned out to be an endothermic and spontaneous process. Compared with other reported materials, the adsorption capacity of X zeolite synthesized from diatomite was among the highest. Therefore, it could be a promising adsorbent for the disposal of wastewater that contains metal ions.

Modelling of pure CO2 and flue gas sorption data on South African coals using Langmuir, Freundlich, Temkin, and Extended Langmuir isotherm models

Greenhouse gases (GHGs) have sharply increased over the past four decades due to intensifying industrial activities; as a result, the earth has been faced with global warming in which the major contributor is the anthropogenic carbon dioxide (CO 2 ) emissions. Carbon sequestration in unmineable coal seams has been proposed as one of the most attractive technologies to mitigate CO 2 emissions in which CO 2 is stored in the microporous structure of the coal matrix in an adsorbed state. The CO 2 adsorption process is hence considered one of the more effective methodologies in environmental sciences. Thus, adsorption isotherm measurements and modelling are key important scientific measures required in understanding the adsorption system, mechanism, and process optimization in coalbeds. In this paper, three renowned adsorption isotherm models were employed including Langmuir, Freundlich, and Temkin for pure CO 2 adsorption data, and the Extended-Langmuir model for multicomponent, such as flue gas mixture-adsorption data as investigated in this research work. The adsorption data was acquired from a high-pressure volumetric sorption system (HPVSS) experiment involving two South African coal samples from Ermelo and Somkhele coalfields with pure CO 2 and synthetic industrial flue gas to simulate emissions that are representative of a typical coal-fired power plant (12% CO 2 , 5.5% O 2 , 82% N 2 , 0.38% SO 2 , and 0.12% NO 2 ). The adsorption data was measured on 10 g samples with a mean size of 2 mm at temperatures ranging from 30 ºC to 60 ºC and pressure up to 9.0 MPa using the HPVSS. The statistical evaluation of the goodness-of-fit was done using three (3) statistical data analysis methods including correlation coefficient (R 2 ), standard deviation ( σ ), and standard error (SE). The Langmuir isotherm model conventionally fits the pure CO 2 gas experimental data better than Freundlich and Temkin. The Extended Langmuir gives best experimental data fit for the flue gas.

Synthesis and Characterization of Methionine-Functionalized Boehmite with Enhanced Removal of Methyl Orange

Methionine, an amino acid with thioether, carboxyl, and amino functional groups, was used to enhance the adsorption capacity of boehmite toward methyl orange (MO). An environmentally friendly synthesis method was performed to prepare the methionine-functionalized boehmite (MFB) at 70°C using water as the solvent. The MFB has prominent XRD characteristic peaks at 2θ = 14.5°, 28.6°, 38.4°, and 48.4°. The addition of functional groups from methionine was indicated by the appearance of FTIR bands at 2094, 1424, and 1220 cm-1 corresponding to carboxyl, amino, and thioether groups, respectively. The N2 isotherm curve indicates the mesoporous structure of MFB, with surface area, pore-volume, and mean pore width of 287 m2 g-1, 0.996 cm3 g-1, 13.85 nm, respectively. The kinetic adsorption data showed a good fitting with the pseudo-first-order model, where the equilibrium can be achieved within 50 min. The adsorption of MO by MFB was better correlated with the Langmuir model with a maximum adsorption capacity of 167.4075 mg g-1, which was achieved at 323 K. The thermodynamic study reveals that the adsorption of MO on MFB was an endothermic and spontaneous process.