scholarly journals Synthesis and characterization of adsorbents for the elimination of nitrates and bromates from water aiming to develop a continuous oxyanion water elimination system

Author(s):  
M. Azaro ◽  
F. M. Flores ◽  
M. Casella ◽  
C. Rodríguez ◽  
R. M. Torres Sánchez ◽  
...  

Abstract It is known that the excess of oxyanions such as NO3- and BrO3- in drinking water affects its quality. In this work, three adsorbents (montmorillonite (Mt), silica (Si), and diatomaceous earth) loaded with hexadecyl- (H) and octadecyl-trimethylammonium (O) were used to remove these oxyanions from aqueous solutions by adsorption. In batch systems, the highest NO3- removal was obtained with Mt modified with H and O (Mt-H and Mt-O), attaining 33 and 50%, respectively, while for BrO3- removal Si modified with H and O, Si-H and Si-O samples, reached 38 and 42%, respectively. A direct relationship between the adsorption capacity of NO3- and BrO3- and the mass of the adsorbent was found in column filtration tests with Mt-O and Mt-H samples in standard solution and real groundwater samples. The adsorption capacity of the column, in the groundwater sample, remained constant after two reuses.The results obtained are promising for the development of a continuous oxyanion removal system containing the low-cost clay Mt modified with either H or O.

2019 ◽  
Vol 41 (1) ◽  
pp. 62-62
Author(s):  
Farida Bouremmad Farida Bouremmad ◽  
Abdennour Bouchair Abdennour Bouchair ◽  
Sorour Semsari Parapari Sorour Semsari Parapari ◽  
Shalima Shawuti and Mehmet Ali Gulgun Shalima Shawuti and Mehmet Ali Gulgun

Biosorbents can be an alternative to activated carbon. They are derived from agricultural by-products or aquatic biomass. They are low cost and they may have comparable performances to those of activated carbon. The present study focuses on the characterization of the Corallina Elongata (CE) alga and its adsorption performance for Methylene Blue (MB), this alga is found in abundance at the Mediterranean coast of the city of Jijel in eastern Algeria. The dried alga was characterized using various characterization techniques such as DTA, TG, FTIR, XRD, SEM and EDX, which showed that the material consists essentially of a calcite containing magnesium. Batch adsorption studies were carried out and the effect of experimental parameters Such as pH, initial dye concentration, temperature, adsorbent dose and contact time, on the adsorption of MB was studied. The kinetic experimental data were found to conform to the pseudo-second-order model with good correlation and equilibrium data were best fitted to The Langmuir model, with a maximum adsorption capacity of 34.4 mg/g. The adsorption isotherms at various temperatures allowed the determination of certain thermodynamic parameters (ΔG, ΔH and ΔS). Finally, the adsorption results showed a good affinity between CE and MB with a high adsorption capacity.


2021 ◽  
Vol 406 ◽  
pp. 457-472
Author(s):  
Aicha Kourim ◽  
Moulay Abderrahmane Malouki ◽  
Aicha Ziouche ◽  
Mouna Boulahbal ◽  
Madjda Mokhtari

In this study, the adsorption of copper Cu (II) from aqueous solution, on Tamanrasset’s clay which is low cost adsorbent, was studied using batch experiments. The adsorption study includes both equilibrium adsorption isotherms and kinetics. The characterization of the adsorbent necessitated several methods such as X-Ray Diffraction, Scanning Electron Microscopy coupled with Energy Dispersive X-ray, BET for specific surface area determination, Fourier transform infrared spectroscopy and thermogravimetric analysis. Indeed, various parameters were investigated such as contact time, initial metal ion concentration, mass of solid, pH of the solution and temperature. The adsorption process as batch study was investigated under the previews experimental parameters. The results revealed that the adsorption capacity of Cu2+ is maximized at naturel pH of metal 5.5. Removal of copper by the clay of Tamanrasset (kaolinite) achieved equilibrium within 50 minutes; the results obtained were found to be fitted by the pseudo-second order kinetics model. The equilibrium process was well described by the Langmuir model and the maximum adsorption capacity was found to be 26.59 mg/g.


Author(s):  
Joshua O. Ighalo ◽  
Ibrahim O. Tijani ◽  
Oluwaseun J. Ajala ◽  
Fisayo O. Ayandele ◽  
Omodele A. Eletta ◽  
...  

Background: Modified bio-based adsorbents from plant sources can be used for pollution remediation by adsorption due to their low cost and availability in large quantities. Objective: In this study, the competitive biosorption of Pb(II) and Cu(II) by Micropogonias undulates functionalised fish scales (FFS) was conducted. The functionalisation was done by wet impregnation with Fe2+. Method: The biosorbent was characterised by Fourier Transform Infrared Spectroscopy (FT-IR), Scanning Electron Microscopy with Energy-Dispersive X-ray Spectroscopy (SEM-EDS) and Branueur–Emmett–Teller (BET) analyses. Results: The major constituents in the FFS were calcium and phosphorus from the collagen and apatite on the scales. Optimum removal efficiency for both metals was >99% at 10 g/l dosage. It was observed that the Langmuir isotherm model and the pseudo second order kinetics model were the best fit for the experimental data. The monolayer adsorption capacity of FFS for Pb(II) and Cu(II) was observed to be 96.15 mg/g and 100 mg/g respectively. Conclusion: The study revealed that the competitive biosorption of heavy metals can be achieved (at a good adsorption capacity) using functionalised Micropogonias undulates fish scales.


2016 ◽  
Vol 1133 ◽  
pp. 547-551 ◽  
Author(s):  
Ali E.I. Elkhalifah ◽  
Mohammad Azmi Bustam ◽  
Azmi Mohd Shariff ◽  
Sami Ullah ◽  
Nadia Riaz ◽  
...  

The present work aims at a better understanding of the influences of the intercalated mono-, di- and triethanolamines on the characteristics and CO2 adsorption ability of sodium form of bentonite (Na-bentonite). The results revealed that the molar mass of intercalated amines significantly influenced the structural and surface properties as well as the CO2 adsorption capacity of Na-bentonite. In this respect, a stepwise increase in the d-spacing of Na-bentonite with the molar mass of amine was recorded by XRD technique. However, an inverse effect of the molar mass of amine on the surface area was confirmed by BET method. CO2 adsorption experiments on amine-bentonite hybrid adsorbents showed that the CO2 adsorption capacity inversly related to the molar mass of amine at 25 ͦC and 101 kPa. Accordingly, Na-bentonite modified by monoethanolammonium cations adsorbed as high as 0.475 mmol CO2/g compared to 0.148 and 0.087 mmol CO2/g for that one treated with di- and triethanolammonium cations, respectively.


Electronics ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 140
Author(s):  
Lichen Liu ◽  
Ziping Cao ◽  
Min Chen ◽  
Jun Jiang

This paper reports the fabrication and characterization of (Bi0.48Sb1.52)Te3 thick films using a tape casting process on glass substrates. A slurry of thermoelectric (Bi0.48Sb1.52)Te3 was developed and cured thick films were annealed in a vacuum chamber at 500–600 °C. The microstructure of these films was analyzed, and the Seebeck coefficient and electric conductivity were tested. It was found that the subsequent annealing process must be carefully designed to achieve good thermoelectric properties of these samples. Conductive films were obtained after annealing and led to acceptable thermoelectric performance. While the properties of these initial materials are not at the level of bulk materials, this work demonstrates that the low-cost tape casting technology is promising for fabricating thermoelectric modules for energy conversion.


Molecules ◽  
2021 ◽  
Vol 26 (12) ◽  
pp. 3718
Author(s):  
Mohammad Azam ◽  
Saikh Mohammad Wabaidur ◽  
Mohammad Rizwan Khan ◽  
Saud I. Al-Resayes ◽  
Mohammad Shahidul Islam

The aim of the research was to prepare low-cost adsorbents, including raw date pits and chemically treated date pits, and to apply these materials to investigate the adsorption behavior of Cr(III) and Cd(II) ions from wastewater. The prepared materials were characterized using SEM, FT-IR and BET surface analysis techniques for investigating the surface morphology, particle size, pore size and surface functionalities of the materials. A series of adsorption processes was conducted in a batch system and optimized by investigating various parameters such as solution pH, contact time, initial metal concentrations and adsorbent dosage. The optimum pH for achieving maximum adsorption capacity was found to be approximately 7.8. The determination of metal ions was conducted using atomic adsorption spectrometry. The experimental results were fitted using isotherm Langmuir and Freundlich equations, and maximum monolayer adsorption capacities for Cr(III) and Cd(II) at 323 K were 1428.5 and 1302.0 mg/g (treated majdool date pits adsorbent) and 1228.5 and 1182.0 mg/g (treated sagai date pits adsorbent), respectively. It was found that the adsorption capacity of H2O2-treated date pits was higher than that of untreated DP. Recovery studies showed maximal metal elution with 0.1 M HCl for all the adsorbents. An 83.3–88.2% and 81.8–86.8% drop in Cr(III) and Cd(II) adsorption, respectively, were found after the five regeneration cycles. The results showed that the Langmuir model gave slightly better results than the Freundlich model for the untreated and treated date pits. Hence, the results demonstrated that the prepared materials could be a low-cost and eco-friendly choice for the remediation of Cr(III) and Cd(II) contaminants from an aqueous solution.


Water ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 459
Author(s):  
Ignacio Cazcarro ◽  
Albert E. Steenge

This article originates from the theoretical and empirical characterization of factors in the World Trade Model (WTM). It first illustrates the usefulness of this type of model for water research to address policy questions related to virtual water trade, water constraints and water scarcity. It also illustrates the importance of certain key decisions regarding the heterogeneity of water and its relation to the technologies being employed and the prices obtained. With regard to WTM, the global economic input–output model in which multiple technologies can produce a “homogeneous output”, it was recently shown that two different mechanisms should be distinguished by which multiple technologies can arise, i.e., from “technology-specific” or from “shared” factors, which implies a mechanism-specific set of prices, quantities and rents. We discuss and extend these characterizations, notably in relation to the real-world characterization of water as a factor (for which we use the terms technology specific, fully shared and “mixed”). We propose that the presence of these separate mechanisms results in the models being sensitive to relatively small variations in specific numerical values. To address this sensitivity, we suggest a specific role for specific (sub)models or key choices to counter unrealistic model outcomes. To support our proposal we present a selection of simulations for aggregated world regions, and show how key results concerning quantities, prices and rents can be subject to considerable change depending on the precise definitions of resource endowments and the technology-specificity of the factors. For instance, depending on the adopted water heterogeneity level, outcomes can vary from relatively low-cost solutions to higher cost ones and can even reach infeasibility. In the main model discussed here (WTM) factor prices are exogenous, which also contributes to the overall numerical sensitivity of the model. All this affects to a large extent our interpretation of the water challenges, which preferably need to be assessed in integrated frameworks, to account for the main socioeconomic variables, technologies and resources.


Author(s):  
Dorota Zając ◽  
Dariusz Przybylski ◽  
Jadwiga Sołoducho

AbstractDeveloping effective and low‐cost organic semiconductors is an opportunity for the development of organic solar cells (OPV). Herein, we report the molecular design, synthesis and characterization of two molecules with D–A–D–A configuration: 2-cyano-3-(5-(8-(3,4-ethylenodioxythiophen-5-yl)-2,3-diphenylquinoxalin-5-yl)thiophen-2-yl)acrylic acid (6) and 2-cyano-3-(5-(2,3-diphenyl-8-(thiophen-2-yl)quinoxalin-5-yl)thiophen-2-yl)acrylic acid (7). Moreover, we investigated the structural, theoretical and optical properties. The distribution of HOMO/LUMO orbitals and the values of the ionization potential indicate good semiconducting properties of the compounds and that they can be a bipolar material. Also, the optical study show good absorption in visible light (λabs 380–550 nm). We investigate the theoretical optoelectronic properties of obtained compounds as potential materials for solar cells.


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