Browse
Keywords
Records with Keyword: Adsorption
Showing records 174 to 198 of 214. [First] Page: 1 4 5 6 7 8 9 Last
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]
Molecular Interpretation of Pharmaceuticals’ Adsorption on Carbon Nanomaterials: Theory Meets Experiments
Daniele Veclani, Marilena Tolazzi, Andrea Melchior
August 5, 2020 (v1)
Keywords: ab initio calculations, Adsorption, carbon nanomaterials, DFT, drugs, isotherms, molecular dynamics, water treatment
The ability of carbon-based nanomaterials (CNM) to interact with a variety of pharmaceutical drugs can be exploited in many applications. In particular, they have been studied both as carriers for in vivo drug delivery and as sorbents for the treatment of water polluted by pharmaceuticals. In recent years, the large number of experimental studies was also assisted by computational work as a tool to provide understanding at molecular level of structural and thermodynamic aspects of adsorption processes. Quantum mechanical methods, especially based on density functional theory (DFT) and classical molecular dynamics (MD) simulations were mainly applied to study adsorption/release of various drugs. This review aims to compare results obtained by theory and experiments, focusing on the adsorption of three classes of compounds: (i) simple organic model molecules; (ii) antimicrobials; (iii) cytostatics. Generally, a good agreement between experimental data (e.g. energies of adsorption, spectr... [more]
MOF-Based Adsorbents for Atmospheric Emission Control: A Review
Nicola Gargiulo, Antonio Peluso, Domenico Caputo
July 17, 2020 (v1)
Subject: Materials
Keywords: Adsorption, atmospheric environment, climate change, greenhouse gases, metal–organic frameworks
This review focuses on the use of metal−organic frameworks (MOFs) for adsorbing gas species that are known to weaken the thermal self-regulation capacities of Earth’s atmosphere. A large section is dedicated to the adsorption of carbon dioxide, while another section is dedicated to the adsorption of other different gas typologies, whose emissions, for various reasons, represent a “wound” for Earth’s atmosphere. High emphasis is given to MOFs that have moved enough ahead in their development process to be currently considered as potentially usable in “real-world” (i.e., out-of-lab) adsorption processes. As a result, there is strong evidence of a wide gap between laboratory results and the industrial implementation of MOF-based adsorbents. Indeed, when a MOF that performs well in a specific process is commercially available in large quantities, economic observations still make designers tend toward more traditional adsorbents. Moreover, there are cases in which a specific MOF remarkably... [more]
Fabrication of Ultrathin MoS2 Nanosheets and Application on Adsorption of Organic Pollutants and Heavy Metals
Siyi Huang, Ziyun You, Yanting Jiang, Fuxiang Zhang, Kaiyang Liu, Yifan Liu, Xiaochen Chen, Yuancai Lv
July 2, 2020 (v1)
Subject: Materials
Keywords: Adsorption, liquid exfoliation, quenching, transition metal dichalcogenides
Owing to their peculiar structural characteristics and potential applications in various fields, the ultrathin MoS2 nanosheets, a typical two-dimensional material, have attracted numerous attentions. In this paper, a hybrid strategy with combination of quenching process and liquid-based exfoliation was employed to fabricate the ultrathin MoS2 nanosheets (MoS2 NS). The obtained MoS2 NS still maintained hexagonal phase (2H-MoS2) and exhibited evident thin layer-structure (1−2 layers) with inconspicuous wrinkle. Besides, the MoS2 NS dispersion showed excellent stability (over 60 days) and high concentration (0.65 ± 0.04 mg mL−1). The MoS2 NS dispersion also displayed evident optical properties, with two characteristic peaks at 615 and 670 nm, and could be quantitatively analyzed with the absorbance at 615 nm in the range of 0.01−0.5 mg mL−1. The adsorption experiments showed that the as-prepared MoS2 NS also exhibited remarkable adsorption performance on the dyes (344.8 and 123.5 mg g−1 o... [more]
Petroleum Hydrocarbon Removal from Wastewaters: A Review
Leili Mohammadi, Abbas Rahdar, Edris Bazrafshan, Hamid Dahmardeh, Md. Abu Bin Hasan Susan, George Z. Kyzas
June 22, 2020 (v1)
Keywords: Adsorption, advanced oxidation, coagulation, oil compounds, removal methods
Oil pollutants, due to their toxicity, mutagenicity, and carcinogenicity, are considered a serious threat to human health and the environment. Petroleum hydrocarbons compounds, for instance, benzene, toluene, ethylbenzene, xylene, are among the natural compounds of crude oil and petrol and are often found in surface and underground water as a result of industrial activities, especially the handling of petrochemicals, reservoir leakage or inappropriate waste disposal processes. Methods based on the conventional wastewater treatment processes are not able to effectively eliminate oil compounds, and the high concentrations of these pollutants, as well as active sludge, may affect the activities and normal efficiency of the refinery. The methods of removal should not involve the production of harmful secondary pollutants in addition to wastewater at the level allowed for discharge into the environment. The output of sewage filtration by coagulation and dissolved air flotation (DAF) floccul... [more]
Simultaneous Adsorption of 4,6-Dimethyldibenzothiophene and Quinoline over Nickel and Boron Modified Gamma-Al2O3 Adsorbent
Esteban Camu, Barbara Pasten, Camila Matus, Fernanda Ramirez, Juan Ojeda, Gonzalo Aguila, Patricio Baeza
June 10, 2020 (v1)
Subject: Materials
Keywords: 4,6-dimethyldibenzothiophene, Adsorption, alumina, boron, nickel, quinoline
The simultaneous adsorption of quinoline and 4,6-dimethyldibenzothiophene over adsorbents, based on alumina modified with boron and nickel under ambient temperature and pressure, was studied. The adsorbents were characterized by BET specific surface area, a potentiometric method for the determination of acid strength, electrophoretic migration, and X-ray diffraction. The results showed that the adsorbent containing nickel had better adsorption capacity than the adsorbent modified with nickel and boron, which was attributed to its greater acidity and ability to generate π-complexation between the adsorbent and the molecules. In terms of selectivity, quinoline was more adsorbed than 4,6-dimethyldibenzothiophene in all systems, due to the basic nature of quinoline. The experimental data in all cases were adjusted by three kinetic models (Yoon−Nelson, Yan and Thomas), and the regression coefficients in all models were close to one. Finally, the values of the kinetic constant obtained by th... [more]
Preparation of Nano-Porous Carbon-Silica Composites and Its Adsorption Capacity to Volatile Organic Compounds
Lipei Fu, Jiahui Zhu, Weiqiu Huang, Jie Fang, Xianhang Sun, Xinya Wang, Kaili Liao
May 22, 2020 (v1)
Subject: Materials
Keywords: Adsorption, carbon-silica composites, dynamic adsorption, regenerating property, volatile organic compounds (VOCs)
Carbon-silica composites with nanoporous structures were synthesized for the adsorption of volatile organic compounds (VOCs), taking tetraethyl orthosilicate (TEOS) as the silicon source and activated carbon powder as the carbon source. The preparation conditions were as follows: the pH of the reaction system was 5.5, the hydrophobic modification time was 50 h, and the dosage of activated carbon was 2 wt%. Infrared spectrum analysis showed that the activated carbon was dispersed in the pores of aerogel to form the carbon-silica composites material. The static adsorption experiments, dynamic adsorption-desorption experiments, and regeneration experiments show that the prepared carbon-silica composites have microporous and mesoporous structures, the adsorption capacity for n-hexane is better than that of conventional hydrophobic silica gel, and the desorption performance is better than that of activated carbon. It still has a high retention rate of adsorption capacity after multiple adso... [more]
Process Parameters Optimization of Gallic Acid Removal from Water by MIEX Resin Based on Response Surface Methodology
Qiang Zhou, Lei Ding, Yunhua Zhu, Meiying Zhong, Chuchu Yang
May 2, 2020 (v1)
Keywords: Adsorption, gallic acid, MIEX resin, process parameters optimization, response surface methodology
In this work, the response surface methodology was used to optimize the process parameters of gallic acid adsorption on magnetic ion exchange (MIEX) resin. Based on Box-Behnken Design, a quadratic polynomial model equation including solution pH, gallic acid concentration, MIEX resin dosage and adsorption time was established. The reliability of the established regression equation was tested by variance analysis. Based on the regression equation, the technical parameters for gallic acid adsorption on MIEX resin were optimized and the effects of interaction between variables on the removal of gallic acid were analyzed. The results showed that the established regression equation was reliable and could effectively predict the removal of gallic acid. The optimal technical parameters were determined to be a pH of 9.17, a gallic acid concentration of 8.07 mg/L, a resin dosage of 0.98 mL/L and an adsorption time of 46.43 min. The removal efficiency of gallic acid was 97.93% under the optimal p... [more]
Improved Removal of Quinoline from Wastewater Using Coke Powder with Inorganic Ions
Lei Wang, Qieyuan Gao, Zhipeng Li, Yongtian Wang
March 25, 2020 (v1)
Subject: Materials
Keywords: Adsorption, coke powder, inorganic ions, quinoline, wastewater treatment
In this paper, laboratory batch adsorption tests were performed to study the adsorption behavior of coke powder in a quinoline aqueous solution with the absence and presence of inorganic ions (K+ and Ca2+). Adsorption isotherms, thermodynamic parameters, and kinetic models were used to understand the sorption mechanism, and zeta potential measurements were performed to elucidate the effect of the inorganic ions on the adsorption. The results showed that coke powder exhibited a reasonably good adsorption performance due to its pore structure and surface characteristics, and the presence of K+ and Ca2+ could further improve the adsorption. Without inorganic ions, the adsorption capacity of coke powder for quinoline and the removal efficiency of quinoline were 1.27 mg/g and 84.90%, respectively. At the ion concentration of 15 mmol, the adsorption capacity of coke powder and quinoline removal efficiency in the presence of K+ reached 1.38 mg/g and 92.02%, respectively, whereas those in the... [more]
Removal of Agrochemicals from Waters by Adsorption: A Critical Comparison among Humic-Like Substances, Zeolites, Porous Oxides, and Magnetic Nanocomposites
Antonello Marocco, Gianfranco Dell’Agli, Filomena Sannino, Serena Esposito, Barbara Bonelli, Paolo Allia, Paola Tiberto, Gabriele Barrera, Michele Pansini
March 12, 2020 (v1)
Subject: Materials
Keywords: Adsorption, agrochemicals, humic-like substances, magnetic nanocomposites, porous oxides, zeolites
The use of humic-like substances, zeolites, various porous oxides (i.e., Al, Fe, or Si oxides), and magnetic nanocomposites in the adsorption of agrochemicals from water was critically reviewed. Firstly, the adsorbents were characterized from the structural, textural, and physico-chemical points of view. Secondly, the fundamental aspects of the adsorption of various agrochemicals on the solids (dependence on pH, kinetics, and isotherm of adsorption) were studied and interpreted on the basis of the adsorbent features. Thirdly, iterative processes of agrochemical removal from water by adsorption on the reported solids were described. In particular, in some cases the residual concentration of agrochemicals in water was lower than the maximum concentration of agrochemicals that the Italian regulations allow to be released in wastewater, surface waters, or sink water.
Enhancing the Removal of Sb (III) from Water: A Fe3O4@HCO Composite Adsorbent Caged in Sodium Alginate Microbeads
Jun Zhang, Renjian Deng, Bozhi Ren, Mohammed Yaseen, Andrew Hursthouse
February 12, 2020 (v1)
Subject: Materials
Keywords: Adsorption, antimony-containing wastewater, ferriferous oxide polishing sludge, microbeads, sodium alginate
To remove antimony (Sb) ions from water, a novel composite adsorbent was fabricated from ferriferous oxide and waste sludge from a chemical polishing process (Fe3O4@HCO) and encapsulated in sodium alginate (SAB). The SAB adsorbent performed well with 80%−96% removal of Sb (III) ions within a concentration range of 5−60 mg/L. The adsorption mechanism of Sb (III) was revealed to be the synergy of chemisorption (ion exchange) and physisorption (diffusion reaction). The adsorption isotherms and kinetics conformed to the Langmuir isotherm and the pesudo-second-order kinetic model. Both initial pH and temperature influenced the adsorption performance with no collapse of microbeads within solution pH range 3−7. Most importantly for practical applications, these microspheres can be separated and recovered from aqueous solution by a magnetic separation technology to facilitate large-scale treatment of antimony-containing wastewater.
Preparation of KOH and H3PO4 Modified Biochar and Its Application in Methylene Blue Removal from Aqueous Solution
Li Liu, Yang Li, Shisuo Fan
January 6, 2020 (v1)
Subject: Materials
Keywords: Adsorption, corn stalk biochar, H3PO4 modification, KOH modification, Methylene blue
Improperly treated or directly discharged into the environment, wastewater containing dyes can destroy the quality of water bodies and pollute the ecological environment. The removal of dye wastewater is urgent and essential. In this study, corn stalk was pyrolyzed to pristine biochar (CSBC) in a limited oxygen atmosphere and modified using KOH and H3PO4 (KOH-CSBC, H3PO4-CSBC, respectively). The biochars were characterized by surface area and pore size, X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), as well as their behavior in adsorbing methylene blue (MB). Results indicated that the pore structure of CSBC became more developed after modification by KOH. Meanwhile, H3PO4-CSBC contained more functional groups after activation treatment. The pseudo-second-order kinetic and the Langmuir adsorption isotherm represented the adsorption process well. The maximum MB adsorption capacity of CSBC, KOH-CSBC, and H3PO4-CSBC was 43.1... [more]
Modifying Nanoporous Carbon through Hydrogen Peroxide Oxidation for Removal of Metronidazole Antibiotics from Simulated Wastewater
Teguh Ariyanto, Rut Aprillia Galuh Sarwendah, Yove Maulana Novirdaus Amimmal, William Teja Laksmana, Imam Prasetyo
December 16, 2019 (v1)
Subject: Materials
Keywords: Adsorption, metronidazole, porous carbon, surface modification, wastewater treatment
This study examined change in pore structure and microstructure of nanoporous carbon after surface oxidation and how it affects the adsorption performance of metronidazole antibiotics. The surface oxidation was performed by hydrogen peroxide at 60 °C. The properties of porous carbon were investigated by N2-sorption analysis (pore structure), scanning electron microscopy (surface morphology), the Boehm titration method (quantification of surface functional group), and Fourier transform infrared spectroscopy (type of surface functional group). The results showed that the oxidation of porous carbon by hydrogen peroxide has a minor defect in the carbon pore structure. Only a slight decrease in specific surface area (8%) from its original value (973 m2g−1) was seen but more mesoporosity was introduced. The oxidation of porous carbon with hydrogen peroxide modified the amount of oxide groups i.e., phenol, carboxylic acid and lactone. Moreover, in the application the oxidized carbon exhibited... [more]
Chromium VI and Fluoride Competitive Adsorption on Different Soils and By-Products
Ana Quintáns-Fondo, Gustavo Ferreira-Coelho, Manuel Arias-Estévez, Juan Carlos Nóvoa-Muñoz, David Fernández-Calviño, Esperanza Álvarez-Rodríguez, María J. Fernández-Sanjurjo, Avelino Núñez-Delgado
December 10, 2019 (v1)
Subject: Materials
Keywords: Adsorption, chromium, competition, fluoride, soil and water pollution
Chromium (as Cr(VI)) and fluoride (F−) are frequently found in effluents from different industrial activities. In cases where these effluents reach soil, it can play an important role in retaining those pollutants. Similarly, different byproducts could act as bio-adsorbents to directly treat polluted waters or to enhance the purging potential of soil. In this work, we used batch-type experiments to study competitive Cr(VI) and F− adsorption in two different soils and several kinds of byproducts. Both soils, as well as mussel shell, oak ash, and hemp waste showed higher adsorption for F−, while pyritic material, pine bark, and sawdust had a higher affinity for Cr(VI). Considering the binary competitive system, a clear competition between both elements in anionic form is shown, with decreases in adsorption of up to 90% for Cr(VI), and of up to 30% for F−. Adsorption results showed better fitting to Freundlich’s than to Langmuir’s model. None of the individual soils or byproducts were abl... [more]
Simulation and Experimental Study of a Single Fixed-Bed Model of Nitrogen Gas Generator Working by Pressure Swing Adsorption
Pham Van Chinh, Nguyen Tuan Hieu, Vu Dinh Tien, Tan-Y Nguyen, Hoang Nam Nguyen, Ngo Thi Anh, Do Van Thom
December 3, 2019 (v1)
Keywords: Adsorption, carbon molecular sieve (CMS), nitrogen, nitrogen generator, pressure swing adsorption (PSA)
Nitrogen is an inert gas available in the air and is widely used in industry and food storage technology. Commonly, it is separated by air refrigerant liquefaction and fractional distillation techniques based on different boiling temperatures of components in the mixed air. Currently, selective adsorption techniques by molecular sieve materials are studied and applied to separate gases based on their molecular size. In this paper, we simulate and investigate the effect parameters in a single fixed-bed model of a nitrogen gas generator using carbon molecular sieves, following pressure swing adsorption. This study aims to identify the effect of changing parameters so as to select the optimal working conditions of a single fixed-bed model, used as a basis for equipment optimization. This equipment was designed, manufactured, and installed at the Institute of Technology, General Department of Defense Industry, Vietnam to investigate, simulate, and optimize the industrial scale-up.
The Removal of Silicate(IV) by Adsorption onto Hydrocalumite from the Sodium Hydroxide Leaching Solution of Black Dross
Thi Thuy Nhi Nguyen, Man Seung Lee
November 24, 2019 (v1)
Subject: Materials
Keywords: Adsorption, alumina, black dross, hydrocalumite, silicate
Alkaline leaching of mechanically activated black dross resulted in an aluminate(III) solution with a small amount of silicate(IV). To obtain pure aluminate(III) solution, the removal of silicate(IV) from the alkaline leaching solution was investigated by adsorption with hydrocalumite (Ca2Al(OH)6Cl·2H2O). The hydrocalumite was synthesized by the coprecipitation method. The characterization of the synthesized hydrocalumite was analyzed via X-ray diffraction (XRD), scanning electron microscopy (SEM) images and Fourier-transform infrared spectroscopy (FTIR). In our experimental conditions, silicate(IV) was selectively adsorbed onto hydrocalumite over aluminate(III). The reaction time greatly affected the removal percentage of aluminate(III) owing to mass action effect. When the reaction time was longer than 2 h, no aluminate(III) was adsorbed onto hydrocalumite and thus it was possible to selectively remove silicate(IV). When the dosage of hydrocalumite was in excess, the removal percenta... [more]
Showing records 174 to 198 of 214. [First] Page: 1 4 5 6 7 8 9 Last
[Show All Keywords]