Comparison of CO2 Separation Efficiency from Flue Gases Based on Commonly Used Methods and Materials

The comparison study of CO2 removal efficiency from flue gases at low pressures and temperatures is presented, based on commonly used methods and materials. Our own experimental results were compared and analyzed for different methods of CO2 removal from flue gases: absorption in a packed column, adsorption in a packed column and membrane separation on polymeric and ceramic membranes, as well as on the developed supported ionic liquid membranes (SILMs). The efficiency and competitiveness comparison of the investigated methods showed that SILMs obtained by coating of the polydimethylsiloxane (PDMS) membrane with 1-ethyl-3-methylimidazolium acetate ([Emim][Ac]) exhibit a high ideal CO2/N2 selectivity of 152, permeability of 2400 barrer and long term stability. Inexpensive and selective SILMs were prepared applying commercial membranes. Under similar experimental conditions, the absorption in aqueous Monoethanolamine (MEA) solutions is much faster than in ionic liquids (ILs), but gas and liquid flow rates in packed column sprayed with IL are limited due to the much higher viscosity and lower diffusion coefficient of IL. For CO2 adsorption on activated carbons impregnated with amine or IL, only a small improvement in the adsorption properties was achieved. The experimental research was compared with the literature data to find a feasible solution based on commercially available methods and materials.

Highly Effective Cow Bone Based Biocomposite for the Sequestration of Organic Pollutant Parameter from Palm Oil Mill Effluent in a Fixed Bed Column Adsorption System

The reduction of chemical oxygen demand (COD) from palm oil mill effluent (POME) is very significant to ensure aquatic protection and the environment. Continuous adsorption of COD in a fixed bed column can be an effective treatment process for its reduction prior to discharge. Adsorption capacity of bone derived biocomposite synthesized from fresh cow bones, zeolite, and coconut shells for the reduction in the organic pollutant parameter was investigated in this study in a fixed bed column. The effect of influent flow rate (1.4, 2.0, and 2.6 mL/min) was determined at an influent pH 7. The optimum bed capacity on the fabricated composite of surface area of 251.9669 m2/g was obtained at 1.4 mL/min at breakthrough time of 5.15 h influent POME concentration. The experimental data were fitted to Thomas, Adams–Bohart, and Yoon–Nelson models fixed bed adsorption models. It was revealed that the results fitted well to the Adams Bohart model with a correlation coefficient of R2 > 0.96 at different influent concentration. Adsorption rate constant was observed to increase at lower flow rate influent concentration, resulting in longer empty bed contact time (EBCT) for the mass transfer zone of the column to reach the outlet of the effluent concentration. In general, the overall kinetics of adsorption indicated that the reduction in COD from POME using a bone-biocomposite was effective at the initial stage of adsorption. The pore diffusion model better described the breakthrough characteristics for COD reduction with high correlation coefficient. Shorter breakthrough time compared to EBCT before regeneration indicated that the bone composite was suitable and effective for the reduction in COD from POME using fixed bed column adsorption.

Cobalt–Carbon Nanoparticles with Silica Support for Uptake of Cationic and Anionic Dyes from Polluted Water

Silica-supported hierarchical graphitic carbon sheltering cobalt nanoparticles Co-HGC@SiO2 (1) were prepared by pyrolysis at 850 °C of [Co(phen)(H2O)4]SO4.2H2O complex with silica in the presence of pyrene as a carbon source under nitrogen atmosphere. Nanocomposites (2) and (3) were obtained by acid treatment of (1) with HCl and HF acid, respectively. The nanocomposites showed rough hierarchical carbon microstructures over silica support decorated with irregular cobalt nanospheres and nanorods 50 to 200 nm in diameter. The nanoparticles consist of graphitic shells and cobalt cores. SEM, EDAX and TEM elemental mapping indicate a noticeable loss of cobalt in the case of (2) and loss of cobalt and silica in the case of (3) with an increase in porosity. Nanocomposite (3) showed the highest BET surface area 217.5 m2g−1. Raman spectrum shows defect D-band and graphitic G-band as expected in carbon nanostructures. PXRD reveals the presence of cobalt(0) nanoparticles. XPS indicates the presence of Co(II) oxides and the successful doping of nitrogen in the nanocomposites. Moreover, TEM elemental mapping provides information about the abundance of Si, Co, C, N and S elements in zones. Nanocomposite (1) showed maximum uptake capacity of 192.3 and 224.5 mg/g for crystal violet CV and methyl orange MO dyes, respectively. Nanocomposite (2) showed a capacity of 94.1 and 225.5 mg/g for CV and MO dyes, respectively. Nanocomposite (4) obtained after treatment of (1) with crystal violet proved successful adsorption of CV. Co-HGC (5) prepared without addition of silica has a capacity for CV equal to 192 mg/g, while it is 769.2 mg/g with MO. Electrostatics and π–π interactions of graphite and cobalt species in the nanocomposites with aromatic rings of cationic and anionic dyes are responsible for the adsorption. Yan et al. was the best model to describe column kinetics. The thomas column adsorption model showed that the maximum uptake capacity of (1) was 44.42 mg/g for CV and 32.62 mg/g for MO. for a column packed with 0.5 gm of (1) and dye concentration of 100 mg/L at a flow rate of 1 mL/min. The column was recycled three times with no noticeable clogging or degradation of nanocomposites. Thus, Co-HGC@SiO2 adsorbents can be used efficiently to treat water contaminated with cationic and anionic dyes.

Humulus scandens-Derived Biochars for the Effective Removal of Heavy Metal Ions: Isotherm/Kinetic Study, Column Adsorption and Mechanism Investigation

Humulus scandens was first adopted as a biomass precursor to prepare biochars by means of a facile molten salt method. The optimized biochar exhibits a high specific surface area of ~450 m2/g−1, a rich porous structure and abundant oxygen functional groups, which demonstrate excellent adsorption performance for heavy metal ions. The isotherm curves fit well with the Langmuir models, indicating that the process is governed by the chemical adsorption, and that the maximum adsorption capacity can reach 748 and 221 mg/g−1 for Pb2+ and Cu2+, respectively. In addition, the optimized biochar demonstrates good anti-interference ability and outstanding removal efficiency for Cu2+ and Pb2+ in simulated wastewater. The mechanism investigation and DFT calculation suggest that the oxygen functional groups play dominant roles in the adsorption process by enhancing the binding energy towards the heavy metal ions. Meanwhile, ion exchange also serves as the main reason for the effective removal.

Optimization of Fluoride Adsorption on Acid Modified Bentonite Clay Using Fixed-Bed Column by Response Surface Method

Using small-scale batch tests, various researchers investigated the adsorptive removal of fluoride using low-cost clay minerals, such as Bentonite. In this study, Column adsorption studies were used to investigate the removal of fluoride from aqueous solution using acid-treated Bentonite (ATB). The effects of initial fluoride concentration, flow rates, and bed depth on fluoride removal efficiency (R) and adsorption capability (qe) in continuous settings were investigated, and the optimal operating condition was determined using central composite design (CCD). The model’s suitability was determined by examining the relationship between experimental and expected response values. The analysis of variance was used to determine the importance of independent variables and their interactions. The optimal values were determined as the initial concentration of 5.51 mg/L, volumetric flow rate of 17.2 mL/min and adsorbent packed-bed depth of 8.88 cm, with % removal of 100, adsorptive capacity of 2.46 mg/g and desirability of 1.0. This output reveals that an acid activation of Bentonite has made the adsorbent successful for field application.

Evaluation of a novel direct capture method for virus concentration n wastewater from COVID-19 infectious ward and correlation analysis with the number of inpatients.

The global outbreak of the SARS-CoV-2 pandemic has increased the focus of Wastewater-based epidemiology (WBE) studies as a tool for understanding the epidemic and risk management. A highly sensitive and rapid method for the virus concentration from wastewater is needed to obtain the accurate information for early detection of SARS-CoV-2 outbreak and epidemic. In this study, we evaluated the efficiency of the direct capture method provided from Promega, based on column adsorption using the wastewater from actual infectious diseases ward. The efficiency of the nucleic acid extraction-purification process was also evaluated by Maxwell RSC instrument (fully automated extraction) and QIAamp Viral RNA mini kit (manual extraction). The obtained SARS-CoV-2 data from wastewater were analyzed with the number of inpatients which is the consideration of the severity and the days of onset. The combination of direct capture and Maxwell's method (DC-MW) was suggested to be a highly sensitive and simple method with better concentration efficiency and quantification than other methods. Moreover, the inpatient conditions (severity and days of after onset) should be considered to accurately understand the actual status of the correlation between the number of inpatients and SARS-CoV-2 concentration in wastewater. The highly sensitive method of DC-MW was suggested to assess more actual situation of SARS-CoV-2 shedding into the wastewater.

ADSORPTION LIQUID CHROMATOGRAPHY OF ETHANOL ELUATE OF ETHANOL EXTRACT OF GREEN WALNUTS+LEAVES (LUGLANS REGIA L., NUT FAMILY - LUGLANDACEAC) (Message VI)

The aim of the study was to perform column adsorption liquid chromatography in order to obtain ethanol eluate, after preliminary sequential elution of ethanol extract with solvents in the order of their polarity: n–hexane, toluene, chloroform, acetone; to study in detail the chemical composition of this eluate by chromatography-mass spectrometry and X-ray fluorescence spectroscopy, with the intensification of compounds determining the composition of eluate, obtaining their masses -spectra, structural formulas, determination of the nature of trace elements. Materials and methods of research. A detailed study of the chemical composition of acetone eluate of ethanol extract of walnuts+ leaves was carried out using column adsorption liquid chromatography, chromato-mass spectrometry and X-ray fluorescence analysis. The results and their discussion. The features of the chemical composition of ethanol eluate of the product of column adsorption liquid chromatography of ethanol extract were studied, the qualitative composition and quantitative content of compounds identified in the first one were established by chromatography-mass spectrometry. Mass spectra and structural formulas were obtained for 31 individual eluate compounds. Ethanol eluate is characterized by the following indicators of structural and group composition (mass. % of eluate): esters of phthalic acid - 52.14, silicon and sulfur-containing compounds, respectively - 20.19 and 6.43, hydrocarbons - 15.38, glycosides - 2.21, alcohols - 1.92, carboxylic acids - 1.07, sterols - 0.89. It is assumed that the pharmacological effect of ethanol eluate is mainly determined by a set of free carboxylic acids, as well as phthalic acid, formed as a result of biochemical and hydrological transesterification of its esters containing compounds, alcohols, glycosides and sterols. Organosilicon compounds during hydrolysis give silica in the size of nanoparticles, which play the role of carriers of the above compounds to various organs of a living organism, as well as drainage of blood vessels from the products of cell metabolism, for example, cholesterol, various fats, etc. A comparative characteristic of the chemical composition of all ethanol extract eluates was carried out, the effectiveness of column adsorption liquid chromatography was shown.

Anionic Dye Removal by Polypyrrole-Modified Red Mud and Its Application to a Lab-Scale Column: Adsorption Performance and Phytotoxicity Assessment

In this study, polypyrrole-modified red mud (PRM) was prepared for the efficient removal of anionic dyes (methyl orange and Congo red) from aqueous solutions. The phytotoxicity (bean sprouts) of the dye solution before and after dye removal was investigated. Adsorption kinetics confirmed that the adsorption of methyl orange (MO) and Congo red (CR) on PRM was controlled by chemical reactions between the functional groups of polypyrrole and dyes. From Langmuir isotherm fitting, we found the theoretical adsorption capacities of MO and CR on PRM were 194.1 and 314.9 mg/g, respectively. The adsorption progress of MO and CR on PRM was found to be spontaneous and endothermic. The column studies demonstrated that, under dynamic flow, the PRM can efficiently remove MO and CR from aqueous solution, with adsorption capacities of 31.08 and 55.04 mg/g, respectively. In the toxicity test, the phytotoxicity of the column effluents (after dye removal) was significantly lowered compared to the initial dye influents. After the removal of MO and CR, the average root length of bean sprouts was increased from 3.30 cm to 5.18 cm and from 3.01 cm to 7.00 cm, respectively. These findings highlighted the efficient removal of dyes by PRM from aqueous solution, demonstrating the possible application of PRM for the removal of dye from dye-contaminated wastewaters.