scholarly journals Alternative Materials for the Enrichment of Biogas with Methane

Materials ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 7759
Author(s):  
Mieczysław Bałys ◽  
Ewelina Brodawka ◽  
Grzegorz Stefan Jodłowski ◽  
Jakub Szczurowski ◽  
Marta Wójcik

Carbonaceous adsorbents have been pointed out as promising adsorbents for the recovery of methane from its mixture with carbon dioxide, including biogas. This is because of the fact that CO2 is more strongly adsorbed and also diffuses faster compared to methane in these materials. Therefore, the present study aimed to test alternative carbonaceous materials for the gas separation process with the purpose of enriching biogas in biomethane and to compare them with the commercial one. Among them was coconut shell activated carbon (AC) as the adsorbent derived from bio-waste, rubber tire pyrolysis char (RPC) as a by-product of waste utilization technology, and carbon molecular sieve (CMS) as the commercial material. The breakthrough experiments were conducted using two mixtures, a methane-rich mixture (consisting of 75% CH4 and 25% CO2) and a carbon dioxide-rich mixture (containing 25% CH4 and 75% CO2). This investigation showed that the AC sample would be a better candidate material for the CH4/CO2 separation using a fixed-bed adsorption column than the commercial CMS sample. It is worth mentioning that due to its poorly developed micropore structure, the RPC sample exhibited limited adsorption capacity for both compounds, particularly for CO2. However, it was observed that for the methane-rich mixture, it was possible to obtain an instantaneous concentration of around 93% CH4. This indicates that there is still much potential for the use of the RPC, but this raw material needs further treatment. The Yoon–Nelson model was used to predict breakthrough curves for the experimental data. The results show that the data for the AC were best fitted with this model.

Author(s):  
Hua Chang ◽  
Tao Ma ◽  
Ling Liu ◽  
Hua-Qiang Yin ◽  
Xue-Dong He

The adsorption capability of carbon dioxide on 13X molecular sieve (13XMS) was investigated in a fixed-bed apparatus with two-road gas mixing system by dynamic column breakthrough method with helium as carrier gas at helium purification conditions of high-temperature gas-cooled reactor (HTGR). Experiments were performed at temperatures of 5°C ∼35 °C and low carbon dioxide partial pressure range of 10∼150Pa. By analyzing the breakthrough curve, both equilibrium adsorption capacity and kinetic adsorption capacity at breakthrough point were determined. Based on mass-transfer zone model, the experimental breakthrough curves at different operation conditions were analyzed. The carbon dioxide isotherm on 13XMS was fitted well by Langmuir model and the enthalpy of adsorption of carbon dioxide was estimated.


Author(s):  
Andressa Regina Vasques ◽  
Selene Maria Arruda Guelli Ulson de Souza ◽  
José Alexandre Borges Valle ◽  
Antônio Augusto Ulson de Souza

The capacity and mechanism of mono and bi-functional reactive dye adsorption utilizing a new adsorbent obtained from the dried residual sludge (~10% w.w.) of a textile wastewater treatment system was studied. With the focus on determining the efficiency of the adsorbent in the dye removal, the adsorption isotherms were determined for the reactive dyes RR2 and RR141, at different temperatures and salt concentrations. The experiments were carried out in fixed bed adsorption columns, which were defined as the best adsorption experimental condition for both of the dyes through the parameter qm (mg/g), obtained by the adjustment of Langmuir isotherms. Breakthrough curves for the dyes RR2 and RR141 were obtained varying the height to which the fixed bed columns were packed with adsorbent (15, 30 and 45 cm) and varying the adsorbate feed rate in the column (8, 12 and 16 ml/min). For the dye RR2 the maximum adsorption capacity was 53.48 mg/g and for the dye RR141 it was 78.74 mg/g.


Author(s):  
Mohammad Akbari Zadeh ◽  
Allahyar Daghbandan ◽  
Behrouz Abbasi Souraki

Abstract Background The presence of iron (Fe) and manganese (Mn) ions in rocky beds leads to groundwater pollution. Moreover, their excessive concentration causes bad taste and color stains of water. Methods Tea leaves-derived char (TLC), rice straw-derived char (RSC), and nanosilica (NS) were used to adsorb Fe and Mn ions from water sources. The effects of parameters such as contact time, composition percentage, and particle size of biosorbents in a fixed-bed adsorption column were investigated. Results The study on the adsorption of Fe and Mn ions showed that the amount of adsorption increased significantly by decreasing the particle size. Furthermore, the combination of nano-biosorbents with nanosilica improved the adsorption. The Thomas and Adams–Bohart models adequately indicated the adsorption of Fe and Mn ions onto nano-biosorbents in the column mode. The TLC and RSC with NS are applicable for the removal of Fe and Mn ions from groundwater. Conclusions According to the BET analysis results, with more crushing of biosorbents by ball mill and placing them in the furnace, specific surface area of tea leaves and rice straw increased from 0.29 to 3.45 and from 3.70 to 10.99 m2/g, respectively. The absorption of iron and manganese from the aqueous solution increased with the percentage of nano-silica. According to breakthrough curves, under best conditions (the seventh mode), nano-biosorbents could remove 98.05% and 97.92% of iron and manganese ions, respectively. The maximum equilibrium capacity of the adsorption column (mg/g) was 256.56 for iron and 244.79 for manganese. Graphical abstract


Energies ◽  
2022 ◽  
Vol 15 (1) ◽  
pp. 347
Author(s):  
Cong Yang ◽  
Yifei Wang ◽  
Abdullatif Alfutimie

To support a sustainable energy development, CO2 reduction for carbon neutralization and water-splitting for hydrogen economy are two feasible technical routes, both of which require a significant input of renewable energies. To efficiently store renewable energies, secondary batteries will be applied in great quantity, so that a considerable amount of energy needs to be invested to eliminate the waste battery electrolyte pollution caused by heavy metals including Cu2+, Zn2+ and Pb2+. To reduce this energy consumption, the removal behaviors of these ions by using clinoptilolite and zeolite A under 5, 7 and 10 BV h−1 in a fixed-bed reactor were investigated. The used zeolites were then regenerated by a novel NH4Cl solution soaking, coupled with the ultrasonication method. Further characterizations were carried out using scanning electron microscopy, N2 adsorption and desorption test, and wide-angle X-ray diffraction. The adsorption breakthrough curves revealed that the leaching preference of clinoptilolite was Pb2+ > Cu2+ > Zn2+, while the removal sequence for zeolite A was Zn2+ > Cu2+ > Pb2+. The maximum removal percentage of Zn2+ ions for clinoptilolite under 5 BV h−1 was 21.55%, while it was 83.45% for zeolite A. The leaching ability difference was also discussed combining with the characterization results. The fact that unit cell stayed the same before and after the regeneration treatment approved the efficacy of the regeneration method, which detached most of the ions while doing little change to both morphology and crystallinity of the zeolites. By evaluating the pH and conductivity changes, the leaching mechanisms by adsorption and ion exchange were further studied.


2013 ◽  
Vol 2013 ◽  
pp. 1-5 ◽  
Author(s):  
Nan Li ◽  
Jing Ren ◽  
Lin Zhao ◽  
Zhong-liang Wang

Removal of phosphate from solution using nanosized FeOOH-modified anion resin was studied in fixed bed column. Effect of bed height and flow rate on the breakthrough curves were investigated. Longer breakthrough time was obtained by increasing the bed height and decreasing the flow rate. Bed service depth time (BDST) model was applied to recount the relationship between bed service time and bed height. The value ofN0was calculated to be 21.4 g/L. Yoon-Nelson model, which fitted well with the experimental data, is allowable to estimate the breakthrough curves and characteristic parameters for phosphate adsorption in the column filled with nanosized FeOOH-modified anion resin.


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