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Records with Keyword: Adsorption
Showing records 1 to 25 of 56. [First] Page: 1 2 3 Last
Nano-Intermediate of Magnetite Nanoparticles Supported on Activated Carbon from Spent Coffee Grounds for Treatment of Wastewater from Oil Industry and Energy Production
Laura Acosta, Dahiana Galeano-Caro, Oscar E. Medina, Farid B. Cortés, Camilo A. Franco
October 14, 2021 (v1)
Keywords: activated carbon, Adsorption, Catalysis, coffee residue, crude oil, magnetite nanoparticles
This work focused on evaluating the adsorptive removal of crude oil using a nano-intermediate based on magnetite nanoparticles supported on activated carbon synthesized from spent coffee grounds and the subsequent catalytic oil decomposition to recover by-products and regenerate the support material. The magnetite nanoparticles were synthesized by the co-precipitation method and were used as active phases on prepared activated carbon. The amount of crude oil adsorbed was determined by adsorption isotherms. In addition, dynamic tests were performed on a packed bed to evaluate the efficiency of the removal process. Thermogravimetric analysis and mass spectrometry were used to evaluate the catalytic powder and the quantification of by-products. Contrasting the results with commercial carbon, the one synthesized from the coffee residue showed a greater affinity for the oil. Likewise, the adsorption capacity increased by doping activated carbon with magnetite nanoparticles, obtaining an eff... [more]
Adsorption as a Process for Produced Water Treatment: A Review
Roghayeh Yousef, Hazim Qiblawey, Muftah H. El-Naas
July 29, 2021 (v1)
Keywords: Adsorption, oil water, produced water, separation, water treatment
Produced water (PW) is a by-product of oil and gas operations, and its production is foreseen to increase in the upcoming years. Such an increase is justified by various entities through their projection of the expected increase in the demand of oil and gas. The treatment of produced water is a significantly growing challenge for the oil and gas industry that requires serious attention. The first part of this review will present the underlying issue of produced water and relevant practices. With adsorption being defined as the least expensive treatment method, the second part will introduce general adsorption principals. The third part will describe the recent applications of adsorption for the treatment of PW with more focus of categorizing the adsorbents as natural and non-natural adsorbents. The main aim of this review is to shed light on the recent research related to PW treatment using adsorption. This is performed to highlight the shortcomings in PW adsorption research and recomm... [more]
Current State of Porous Carbon for Wastewater Treatment
Mongi ben Mosbah, Lassaad Mechi, Ramzi Khiari, Younes Moussaoui
July 29, 2021 (v1)
Subject: Materials
Keywords: activated carbon, activating agent, Adsorption, applications, Biomass, pollutants, porous materials
Porous materials constitute an attractive research field due to their high specific surfaces; high chemical stabilities; abundant pores; special electrical, optical, thermal, and mechanical properties; and their often higher reactivities. These materials are currently generating a great deal of enthusiasm, and they have been used in large and diverse applications, such as those relating to sensors and biosensors, catalysis and biocatalysis, separation and purification techniques, acoustic and electrical insulation, transport gas or charged species, drug delivery, and electrochemistry. Porous carbons are an important class of porous materials that have grown rapidly in recent years. They have the advantages of a tunable pore structure, good physical and chemical stability, a variable specific surface, and the possibility of easy functionalization. This gives them new properties and allows them to improve their performance for a given application. This review paper intends to understand... [more]
Improving Ammonium Sorption of Bayah Natural Zeolites by Hydrothermal Method
Teguh Kurniawan, Saiful Bahri, Anita Diyanah, Natasya D. Milenia, Nuryoto Nuryoto, Kajornsak Faungnawakij, Sutarat Thongratkaew, Muhammad Roil Bilad, Nurul Huda
June 29, 2021 (v1)
Subject: Materials
Keywords: Adsorption, clinoptilolite, crystallinity, Freundlich, intraparticle, ion-exchange, isotherm, kinetic, mordenite, surface area
Natural zeolites are easily found and abundant in Indonesia. The natural zeolites are low-cost minerals; however, their ammonium sorption is poor. A hydrothermal method was applied to improve the ammonium sorption. Hydrothermal treatment times were varied 8, 24, and 32 h. The parent and hydrothermal treated samples were characterized by using X-ray diffraction (XRD), Field Emission Scanning Electron Microscopes (FE-SEM), Fourier-transform infrared spectroscopy (FTIR), and nitrogen physisorption. Ammonium adsorption was performed using a batch reactor to evaluate the adsorption performance of the prepared zeolite samples. The 8 h hydrothermal (HT 8 h) treated zeolites showed the highest ammonium removal percentage among others. The XRD analysis of HT 8 h shows a higher crystallinity of mordenite and the Brunauer−Emmett−Teller (BET) model shows a surface area of 105 m2/g, much larger as compared to the parent with a surface area of 19 m2/g. Various kinetic and isotherms models were also... [more]
Preparation and Characterization of Activated Carbon Obtained from Water Treatment Plant Sludge for Removal of Cationic Dye from Wastewater
Alaor Valério Filho, Raíssa Xavaré Kulman, Luana Vaz Tholozan, André Ricardo Felkl de Almeida, Gabriela Silveira da Rosa
June 21, 2021 (v1)
Subject: Materials
Keywords: activated sludge carbon, Adsorption, dye removal, methylene blue, wastewater treatment
The proposal of this work was the preparation and characterization of activated carbons obtained from water treatment plant sludge (WTS) to apply as adsorbents in the removal of organic dye contaminants from wastewater. The activated carbons were produced with a combination of chemical activation and pyrolysis processes. The textural characteristics of both adsorbents presented a satisfactory superficial area and mesoporous structure. The presence of phenolic and carboxylic groups in the surface indicated a better adsorption of cationic adsorbates. When applied as adsorbents in the removal of methylene blue (MB) from wastewater, the maximum removal values obtained were up to 96%. The adsorption results showed that the adsorption was faster in the beginning and reached maximum around 30 min. The Elovich kinetic model and the Sips isotherm model presented the best fit to experimental data, which was checked by analysis of variance (ANOVA). The production of activated carbons from WTS is... [more]
Adsorption of CO2 on Amine-Modified Silica Particles in a Confined-Fluidized Bed
Rossella Girimonte, Flaviano Testa, Marta Gallo, Rocco Buscieti, Giuseppe Leone, Brunello Formisani
June 21, 2021 (v1)
Keywords: Adsorption, amine-based adsorbents, Carbon Dioxide Capture, confined-fluidized bed, mesoporous silica gel, packed-fluidized bed
To reduce the anthropogenic CO2 emissions produced from fossil fuel burning plants, the application of carbon capture and storage (CCS) is necessary and development of a more efficient and economically feasible CO2 capture process is essential as an alternative to the conventional amine scrubbing process which uses aqueous amine solutions. CO2 capture can be enhanced by improving both the gas−solid contact efficiency and by tuning a specific high-performance sorbent. The aim of this research is to investigate the adsorption of CO2 using impregnated mesoporous silica in a “confined-fluidized bed”. This non-conventional fluidized bed (sometimes also termed the “packed-fluidized bed”) seems suitable for improving the efficiency of gas−solid processes for which the bypass effect of the gas−solid contact caused by bubbling represents a major drawback. Results, expressed as grams of CO2 adsorbed per kilogram of material, are discussed in terms of amine load in the sorbent, breakthrough time... [more]
New Porous Silicon-Containing Organic Polymers: Synthesis and Carbon Dioxide Uptake
Safaa H. Mohamed, Ayad S. Hameed, Emad Yousif, Mohammad Hayal Alotaibi, Dina S. Ahmed, Gamal A. El-Hiti
June 2, 2021 (v1)
Subject: Materials
Keywords: Adsorption, carbon dioxide storage, polysilicates, porous organic polymers, Schiff base
The design and synthesis of new multifunctional organic porous polymers has attracted significant attention over the years due to their favorable properties, which make them suitable for carbon dioxide storage. In this study, 2-, 3-, and 4-hydroxybenzaldehyde reacted with phenyltrichlorosilane in the presence of a base, affording the corresponding organosilicons 1−3, which further reacted with benzidine in the presence of glacial acetic acid, yielding the organic polymers 4−6. The synthesized polymers exhibited microporous structures with a surface area of 8.174−18.012 m2 g−1, while their pore volume and total average pore diameter ranged from 0.015−0.035 cm3 g−1 and 1.947−1.952 nm, respectively. In addition, among the synthesized organic polymers, the one with the meta-arrangement structure 5 showed the highest carbon dioxide adsorption capacity at 323 K and 40 bar due to its relatively high surface area and pore volume.
Tetracycline and Sulfonamide Antibiotics in Soils: Presence, Fate and Environmental Risks
Manuel Conde-Cid, Avelino Núñez-Delgado, María José Fernández-Sanjurjo, Esperanza Álvarez-Rodríguez, David Fernández-Calviño, Manuel Arias-Estévez
May 27, 2021 (v1)
Keywords: Adsorption, crops, degradation, desorption, food chain, microorganisms, transport, veterinary antibiotics, water bodies
Veterinary antibiotics are widely used worldwide to treat and prevent infectious diseases, as well as (in countries where allowed) to promote growth and improve feeding efficiency of food-producing animals in livestock activities. Among the different antibiotic classes, tetracyclines and sulfonamides are two of the most used for veterinary proposals. Due to the fact that these compounds are poorly absorbed in the gut of animals, a significant proportion (up to ~90%) of them are excreted unchanged, thus reaching the environment mainly through the application of manures and slurries as fertilizers in agricultural fields. Once in the soil, antibiotics are subjected to a series of physicochemical and biological processes, which depend both on the antibiotic nature and soil characteristics. Adsorption/desorption to soil particles and degradation are the main processes that will affect the persistence, bioavailability, and environmental fate of these pollutants, thus determining their potent... [more]
A Methodology to Estimate the Sorption Parameters from Batch and Column Tests: The Case Study of Methylene Blue Sorption onto Banana Peels
Anastasia Stavrinou, Christos A. Aggelopoulos, Christos D. Tsakiroglou
May 27, 2021 (v1)
Keywords: Adsorption, banana peels, breakthrough curve, methylene blue, sorption models, thermodynamics
In the present work, a methodology is presented where batch and fixed-bed column tests of dye sorption onto granular biosorbents are analyzed with properly selected models to estimate the parameters required for the rational design of pilot-scale units. The sorption of methylene blue (MB) onto banana peels (BP) was investigated as a case study. To identify the mechanisms of MB sorption onto BP, the pore structure and surface of BP were characterized with mercury intrusion porosimetry (MIP), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). Batch tests were performed over the temperature range of 15−45 °C, and three models (Langmuir, Freundlich, Langmuir−Freundlich) were fitted to equilibrium and kinetic data for (i) estimating thermodynamic/kinetic parameters and (ii) choosing the model with the best goodness-of-fit. Sorption tests on fixed-bed columns were combined with a one-dimensional macroscopic convection/dispersion/sorption model to estimate... [more]
Carbon Dioxide Capture in Homogeneous and Heterogeneous Surfaces of Porous Silica Glass
Chontira Boonfung, Chaiyot Tangsathitkulchai, Atichat Wongkoblap
April 27, 2021 (v1)
Subject: Materials
Keywords: Adsorption, Carbon Dioxide Capture, defective surface, Grand Canonical Monte Carlo, porous silica glass, surface functional groups
Experimental and simulation studies for carbon dioxide (CO2) adsorption on porous silica glass were performed to reveal how surface heterogeneity can affect the adsorption mechanism of CO2. In performing the simulation, the structure of porous silica glass was modeled as a slit pore consisting of parallel walls of connected SiO4 units. The adsorption isotherms of CO2 at 283 K were generated for a series of pore widths using a Monte Carlo ensemble. The defective surfaces created by random removal of surface atoms and the surfaces containing hydroxyl functional groups were chosen to represent the surface heterogeneity for the simulation tasks. The isotherms derived for the defective surfaces showed a rapid adsorption at low pressures because of the stronger interaction between the rough nonuniform surfaces and CO2 molecules. For the role of surface functional groups, the adsorption isotherms dramatically increased with an increasing number of functional groups. The amount of CO2 adsorbed... [more]
Biocarbon Derived from Opuntia ficus indica for p-Nitrophenol Retention
Hanedi Elhleli, Faten Mannai, Mongi ben Mosbah, Ramzi Khiari, Younes Moussaoui
April 27, 2021 (v1)
Keywords: activated carbon, Adsorption, Opuntia ficus indica, p-nitrophenol, porous carbon
Activated carbon obtained from Opuntia ficus indica by sodium hydroxide activation was employed for the adsorption of p-nitrophenol from water. The activated carbons obtained were characterized by Fourier transforms infrared spectroscopy, sorption of nitrogen, scanning electron microscopy, and Boehm titration. Effects of pH, contact time, amount of adsorbent, and temperature on the adsorption of p-nitrophenol were studied. Adsorption isotherms were analyzed using Freundlich, Langmuir, Temkin, and Dubinin-Radushkevich models, and the thermodynamic parameters have been determined. The adsorption of p-nitrophenol was spontaneous, exothermic, and propitious at 15 °C and adopted the pseudo-second order model, and the most credible isotherm was Langmuir’s one. The activated carbon used in this work has good p-nitrophenol adsorption characteristics, and the study of the desorption and reuse of this carbon shows that it retains a removal rate greater than 94% after five cycles of adsorption-de... [more]
Effect of Hydration Layer on the Adsorption of Dodecane Collector on Low-Rank Coal: A Molecular Dynamics Simulation Study
Lingyun Liu, Erle Qiao, Liang Shen, Fanfei Min, Changguo Xue
April 16, 2021 (v1)
Keywords: Adsorption, hydration layer, low-rank coal, molecular dynamics simulation
The hydration layer has a significant effect on the adsorption behavior of reagents during the flotation process of low-rank coal. Understanding the effect of hydration layer on the adsorption of common collectors on low-rank coal is a prerequisite for proposing a new enhanced coal floatation method. In this study, a smooth low-rank coal surface model with a density of 1.2 g/cm3 was constructed and compared with the XPS results. Three different systems, coal-water, coal-collector, and coal-water-collector, were constructed. Molecular dynamics method was applied to study the adsorption behaviors of water and dodecane molecules. Simulation results revealed that a stable hydration layer with a thickness of about 5 Å was formed due to the strong attraction of coal surface. The negative value of interaction energy (IE) indicated that dodecane molecules could spontaneously adsorb on the coal surface. Dodecane molecules were successfully adsorbed on the coal surface when it was located inside... [more]
Cu(II) and As(V) Adsorption Kinetic Characteristic of the Multifunctional Amino Groups in Chitosan
Byungryul An
April 16, 2021 (v1)
Keywords: Adsorption, amino group, anion, cation, kinetic, multifunction
Amino groups in the chitosan polymer play as a functional group for the removal of cations and anions depending on the degree of protonation, which is determined by the solution pH. A hydrogel beadlike porous adsorbent was used to investigate the functions and adsorption mechanism of the amino groups by removal of Cu(II) as a cation and As(V) as an anion for a single and mixed solution. The uptakes of Cu(II) and As(V) were 5.2 and 5.6 μmol/g for the single solution and 5.9 and 3.6 μmol/g for the mixed solution, respectively. The increased total capacity in the presence of both the cation and anion indicated that the amino group (NH2 or NH3+) species was directly associated for adsorption. The application of a pseudo second-order (PSO) kinetic model was more suitable and resulted in an accurate correlation coefficient (R2) compared with the pseudo first-order (PFO) kinetic model for all experimental conditions. Due to poor linearization of the PFO reaction model, we attempted to divide... [more]
Degradation of Direct Blue 1 through Heterogeneous Photocatalysis with TiO2 Irradiated with E-Beam
Elvia Gallegos, Florinella Muñoz Bisesti, Katherine Vaca-Escobar, Cristian Santacruz, Lenys Fernández, Alexis Debut, Patricio J. Espinoza-Montero
April 16, 2021 (v1)
Keywords: Adsorption, Direct Blue 1, electron-beam, heterogeneous photocatalysis, irradiated TiO2
Most dyes used in the textile industry are chemically stable and poorly biodegradable, therefore, they are persistent in the environment and difficult to degrade by conventional methods. An alternative treatment for this kind of substance is heterogeneous photocatalysis using TiO2, so, in this work, it is proposed to degrade Direct Blue 1 (DB1) using microparticulate TiO2 irradiated with e-beam at three different doses: 5, 10 and 20 kGy (J/kg). The DB1 degradation was implemented in a batch reactor (DB1 initial concentration = 50 mg L−1, pH 2.5, TiO2 concentration = 200 mg L−1). We have demonstrated that the photocatalytic power of TiO2, when irradiated with e-beam (5, 10, 20 kGy), varies slightly, with minor effects on photodegradation performance. However, the dose of 10 kGy showed a slightly better result, according to the DB1 photodegradation rate constant. Adsorption process was not affected by irradiation; its isotherm was fitted to Freundlich’s mathematical model. The DB1 photod... [more]
Scale-Up of Self-Regenerating Semi-Batch Adsorption Cycles through Concurrent Adsorption and Reduction of Cr(VI) on Sheep Wool
Mohamed Badrelzaman, Mustafa I. Khamis, Taleb H. Ibrahim, Fawwaz H. Jumean
March 1, 2021 (v1)
Keywords: Adsorption, hexavalent chromium, industrial wastewater, semi-batch adsorption cycles, wool
A previous publication by our group reported that adsorption of Cr(VI) on sheep wool reached 99% when allowed a long residence time, with concurrent reduction to Cr(III). In this study, the process was scaled up by optimizing a pilot plant based on semi-batch adsorption cycles. This yielded Cr(III), which is about 300 times less toxic than Cr(VI), and can be precipitated using lime at high pH. Since the reduction step is slower than the adsorption one, an adsorption column was designed to perform semi-batch operation cycles, whereby the extended “off cycle” allows reduction to take place. Since reduction of Cr(VI) frees active sites on wool, the plant acts in lieu of in situ regeneration, accompanied by additional adsorption of Cr(VI). The results show that 97% of the column efficiency can be recovered within 24 h of “off cycle”. Wastewater from a local electroplating industry was treated by this method with high removal of Cr(VI), reaching the limit permitted by environmental standard... [more]
Study of H2S Removal Capability from Simulated Biogas by Using Waste-Derived Adsorbent Materials
Hua Lun Zhu, Davide Papurello, Marta Gandiglio, Andrea Lanzini, Isil Akpinar, Paul R. Shearing, George Manos, Dan J.L. Brett, Ye Shui Zhang
February 3, 2021 (v1)
Keywords: activated carbon, Adsorption, biochar, Catalysis, circular economy, H2S, waste
Three waste-derived adsorbent materials (wood-derived biochar, sludge-derived activated carbon and activated ash) were pre-activated at the laboratory scale to apply them for the removal of H2S from a biogas stream. The H2S removal capabilities of each material were measured by a mass spectrometer, to detect the H2S concentration after the adsorption in an ambient environment. The activated ash adsorbent has the highest removal capacity at 3.22 mgH2S g−1, while wood-derived biochar has slightly lower H2S removal capability (2.2 mgH2S g−1). The physicochemical properties of pristine and spent materials were characterized by the thermogravimetric analyzer, elemental analysis, X-ray fluorescence spectroscopy and N2 adsorption and desorption. Wood-derived biochar is a highly porous material that adsorbs H2S by physical adsorption of the mesoporous structure. Activated ash is a non-porous material which adsorbs H2S by the reaction between the alkaline compositions and H2S. This study shows... [more]
Efficient Removal of Ni(II) from Aqueous Solution by Date Seeds Powder Biosorbent: Adsorption Kinetics, Isotherm and Thermodynamics
Abubakr Elkhaleefa, Ismat H. Ali, Eid I. Brima, A. B. Elhag, Babiker Karama
December 22, 2020 (v1)
Keywords: Adsorption, date seeds, isotherm, kinetics, thermodynamics
Adsorption investigations in batch approaches were performed to explore the biosorption of Ni(II) ions from aqueous solutions on date seeds powder. The effects of pH, particle size, initial concentration of Ni(II) ions, adsorbent mass, temperature, and contact on the adsorption efficacy were studied. The maximum removal obtained was 90% for an original Ni(II) ion solution concentration of 50 ppm was attained at pH 7 after 30 min and with 0.30 g of an added adsorbent. The four adsorption models, namely Freundlich, Langmuir, Dubinin−Radushkevich (D−R), and Temkin were examined to fit the experimental findings. The adsorption system obeys the Freundlich model. The system was found to follow the pseudo-second order kinetic model. Thermodynamic factors; entropy (ΔS°), enthalpy (ΔH°), and Gibbs free energy (ΔG°) changes were also assessed. Results proved that adsorption of Ni(II) ions is exothermic and spontaneous. Sticking probability value was found to be less than unity, concluding that t... [more]
Magnetic Multiwall Carbon Nanotube Decorated with Novel Functionalities: Synthesis and Application as Adsorbents for Lead Removal from Aqueous Medium
Ghadir Hanbali, Shehdeh Jodeh, Othman Hamed, Roland Bol, Bayan Khalaf, Asma Qdemat, Subhi Samhan, Omar Dagdag
December 22, 2020 (v1)
Subject: Materials
Keywords: Adsorption, isotherm, kinetics, lead, magnetic multiwall carbon nanotube, thermodynamic
Water pollution is one of the major challenges facing modern society because of industrial development and urban growth. This study is directed towards assessing the use of multiwall carbon nanotube, after derivatization and magnetization, as a new and renewable absorbent, to remove toxic metal ions from waste streams. The adsorbents were prepared by, first oxidation of multiwall carbon nanotube, then derivatizing the oxidized product with hydroxyl amine, hydrazine and amino acid. The adsorbents were characterized by various techniques. The adsorption efficiency of the multiwall carbon nanotube adsorbents toward Pb(II) was investigated. The effect of adsorbent’s dose, temperature, pH, and time on the adsorption efficiency were studied and the adsorption parameters that gave the highest efficiency were determined. The derivatives have unique coordination sites that included amine, hydroxyl, and carboxyl groups, which are excellent chelating agents for metal ions. The thermodynamic and k... [more]
Residue Char Derived from Microwave-Assisted Pyrolysis of Sludge as Adsorbent for the Removal of Methylene Blue from Aqueous Solutions
Gong Cheng, Yazhuo Li, Liming Sun, Siyi Luo, George Z. Kyzas, Jie Fu
December 22, 2020 (v1)
Keywords: Adsorption, methylene blue, microwave pyrolysis, residue char, sewage sludge
Residue char is the main by-product of the microwave-assisted pyrolysis of activated sludge and it has a high content of fixed carbon and porous structure, but little is known about its character as an absorbent. In this study, residue char of activated sludge with microwave-assisted pyrolysis was used as an adsorbent to absorb methylene blue. The effects of pyrolysis temperature, pyrolysis holding time, contact time, and adsorption temperature on the adsorption ability of residue char were investigated. Kinetics, isotherm, and thermodynamic models were also included to study the adsorption behavior. The results showed that the optimal pyrolysis condition was 15 min and 603 °C, and the adsorption capacity reached up to 80.01 mg/g. The kinetics analyses indicated the adsorption behavior followed the pseudo-second-order kinetics model and the adsorption process was mainly due to chemical interaction. The adsorption isotherm was described by Freundlich model and thus, its process was mult... [more]
Mechanism of Permeability and Oil Recovery during Fracturing in Tight Oil Reservoirs
Yujie Bai, Guangsheng Cao, Guanglei Wei, Xiaohan Nan, Qingchao Cheng, Tong Du, Hongxin An
December 22, 2020 (v1)
Subject: Other
Keywords: Adsorption, enhanced oil recovery, imbibition, surfactant, tight oil
In this study, the effect of fracturing fluid on the permeability of tight oil reservoirs is analyzed through oil absorption. The mechanism of permeation and absorption in tight oil reservoirs was studied using the molecular dynamics simulation of fluid flow through fractures in porous media containing crude oil. The influence of surfactants on the adsorption characteristics of crude oil formations on rock walls was also examined. The research results show that the introduction of the appropriate surfactant to the fracturing fluid could accelerate the rate of percolation and recovery as well as improve the recovery rate of absorption. The optimal concentration of polyoxyethylene octyl phenol ether-10 (OP-10) surfactant in the fracturing fluid was 0.9%. When the percolation reached a certain stage, the capillary forces in the crude oil and percolation medium in the pore stabilized; accordingly, the crude oil from the pore roar should be discharged at the earliest. The fluid flow through... [more]
Upgrading of Biogas to Methane Based on Adsorption
Jun Liu, Qiang Chen, Peng Qi
December 17, 2020 (v1)
Subject: Materials
Keywords: 13X zeolite, Adsorption, biogas, carbon molecular sieve, methane
Upgrading raw biogas to methane (CH4) is a vital prerequisite for the utilization of biogas as a vehicle fuel or the similar field as well. In this work, biogas yield from the anaerobic fermentation of food waste containing methane (CH4, 60.4%), carbon dioxide (CO2, 29.1%), hydrogen sulfide (H2S, 1.5%), nitrogen (N2, 7.35%) and oxygen (O2, 1.6%) was upgraded by dynamic adsorption. The hydrogen sulfide was removed from the biogas in advance by iron oxide (Fe2O3) because of its corrosion of the equipment. Commercial 13X zeolite and carbon molecular sieve (CMS) were used to remove the other impurity gases from wet or dry biogas. It was found that neither 13X zeolite nor CMS could effectively remove each of the impurities in the wet biogas for the effect of water vapor. However, 13X zeolite could effectively remove CO2 after the biogas was dried with silica and showed a CO2 adsorption capacity of 78 mg/g at the condition of 0.2 MPa and 25 °C. Additionally, 13X zeolite almost did not adsorb... [more]
Study of the Digestate as an Innovative and Low-Cost Adsorbent for the Removal of Dyes in Wastewater
Sicong Yao, Massimiliano Fabbricino, Marco Race, Alberto Ferraro, Ludovico Pontoni, Oriella Aimone, Yao Chen
November 9, 2020 (v1)
Keywords: adsorbent, Adsorption, digestate, dye, isotherm model, kinetic model
Digestate, as an urban solid waste, was considered as an innovative adsorbent for colorant polluted wastewater. Batch adsorption experiments were carried out using digestate as an adsorbent material to remove various dyes belonging to different categories. The removal rate and adsorption capacity of dyes were evaluated and the dose of digestate, contact time, and initial dye concentration were studied. The maximum removal rate was approximately 96% for Methylene Blue. The equilibrium time for the Methylene Blue was 4 h, while for other dyes, a longer contact time was required to reach the equilibrium. The suspicion of colloidal matter release into the solution from solid fraction of the digestate led to the investigation of the consequence of a washing step of the digestate adsorbent upstream the adsorption experiment. Washed and not washed adsorbents were tested and the differences between them in terms of dye removal were compared. Moreover, experimental data were fitted by pseudo-fi... [more]
A Fractal-Based Correlation for Time-Dependent Surface Diffusivity in Porous Adsorbents
Vassilis J. Inglezakis, Marco Balsamo, Fabio Montagnaro
September 15, 2020 (v1)
Keywords: Adsorption, fractal-like dynamics, hindered diffusion, hopping, surface diffusivity, zeolites
Fluid−solid adsorption processes are mostly governed by the adsorbate transport in the solid phase and surface diffusion is often the limiting step of the overall process in microporous materials such as zeolites. This work starts from a concise review of concepts and models for surface transport and variable surface diffusivity. It emerges that the phenomenon of hindered surface diffusion for monolayer adsorption, which is common in zeolites, and models able to fit a non-monotonic trend of surface diffusivity against adsorbate solid phase concentration, have received limited attention. This work contributes to the literature of hindered diffusion by formulating a time-dependent equation for surface diffusivity based on fractal dynamics concepts. The proposed equation takes into account the contributions of both fractal-like diffusion (a time-decreasing term) and hopping diffusion (a time-increasing term). The equation is discussed and numerically analyzed to testify its ability to rep... [more]
Kinetics, Isotherms, and Thermodynamic Modeling of the Adsorption of Phosphates from Model Wastewater Using Recycled Brick Waste
Uduakobong A. Edet, Augustine O. Ifelebuegu
August 29, 2020 (v1)
Keywords: Adsorption, brick particles, phosphates, recycle, Wastewater
Phosphates in wastewater at elevated concentrations cause eutrophication of water bodies and their removal from treated wastewater is essential before effluents are discharged to the environment. Phosphates are predominately removed during wastewater treatment by chemical precipitation which is usually expensive and has a significant environmental footprint. The purpose of this study was to investigate the effectiveness of waste recycled bricks as adsorbent for phosphate removal during wastewater treatment. The kinetics, isotherms, and thermodynamics of adsorption were investigated to establish the mechanisms of adsorption. The results showed that adsorption capacities increased with an increase in contact time, adsorbent dosage, and initial phosphate concentration. The kinetic study indicated that adsorption was governed by several mechanisms with various processes dominating different stages of the adsorption. The adsorption process was better represented by the pseudo-second-order k... [more]
Efficacies of Carbon-Based Adsorbents for Carbon Dioxide Capture
Tasmina Khandaker, Muhammad Sarwar Hossain, Palash Kumar Dhar, Md. Saifur Rahman, Md. Ashraf Hossain, Mohammad Boshir Ahmed
August 29, 2020 (v1)
Subject: Materials
Keywords: activated carbon, Adsorption, Carbon Dioxide Capture, carbon nanomaterials, surface area
Carbon dioxide (CO2), a major greenhouse gas, capture has recently become a crucial technological solution to reduce atmospheric emissions from fossil fuel burning. Thereafter, many efforts have been put forwarded to reduce the burden on climate change by capturing and separating CO2, especially from larger power plants and from the air through the utilization of different technologies (e.g., membrane, absorption, microbial, cryogenic, chemical looping, and so on). Those technologies have often suffered from high operating costs and huge energy consumption. On the right side, physical process, such as adsorption, is a cost-effective process, which has been widely used to adsorb different contaminants, including CO2. Henceforth, this review covered the overall efficacies of CO2 adsorption from air at 196 K to 343 K and different pressures by the carbon-based materials (CBMs). Subsequently, we also addressed the associated challenges and future opportunities for CBMs. According to this r... [more]
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