scholarly journals The Manufacture and Characterisation of Rosid Angiosperm-Derived Biochars Applied to Water Treatment

2019 ◽  
Vol 13 (1) ◽  
pp. 387-396 ◽  
Author(s):  
Gideon A. Idowu ◽  
Ashleigh J. Fletcher

AbstractMarabu (Dichrostachys cinerea) from Cuba and aspen (Populus tremula) from Britain are two rosid angiosperms that grow easily, as a weed and as a phytoremediator, respectively. As part of scientific efforts to valorise these species, their barks and woods were pyrolysed at 350, 450, 550 and 650 °C, and the resulting biochars were characterised to determine the potential of the products for particular applications. Percentage carbon composition of the biochars generally increased with pyrolysis temperature, giving biochars with highest carbon contents at 650 °C. Biochars produced from the core marabu and aspen wood sections had higher carbon contents (up to 85%) and BET surface areas (up to 381 m2 g−1) than those produced from the barks. The biochar porous structures were predominantly mesoporous, while micropores were developed in marabu biochars produced at 650 °C and aspen biochars produced above 550 °C. Chemical and thermal activation of marabu carbon greatly enhanced its adsorption capacity for metaldehyde, a molluscicide that has been detected frequently in UK natural waters above the recommended EU limit.

1998 ◽  
Vol 37 (12) ◽  
pp. 263-267 ◽  
Author(s):  
Henry O. Edwards

The development of a sensor to measure colour and turbidity of natural waters is described. Filtration of the water is not required, so maintenance intervals and costs will be reduced. A four-beam intensity compensation technique is used for robust measurement and resistance to fouling. Results of the operation of a prototype at a water treatment works are presented.


J ◽  
2021 ◽  
Vol 4 (2) ◽  
pp. 193-205
Author(s):  
Opeyemi A. Oyewo ◽  
Sam Ramaila ◽  
Lydia Mavuru ◽  
Taile Leswifi ◽  
Maurice S. Onyango

The presence of toxic metals in surface and natural waters, even at trace levels, poses a great danger to humans and the ecosystem. Although the combination of adsorption and coagulation techniques has the potential to eradicate this problem, the use of inappropriate media remains a major drawback. This study reports on the application of NaNO2/NaHCO3 modified sawdust-based cellulose nanocrystals (MCNC) as both coagulant and adsorbent for the removal of Cu, Fe and Pb from aqueous solution. The surface modified coagulants, prepared by electrostatic interactions, were characterized using Fourier transform infrared, X-ray diffraction (XRD), and scanning electron microscopy/energy-dispersive spectrometry (SEM/EDS). The amount of coagulated/adsorbed trace metals was then analysed using inductively coupled plasma atomic emission spectroscopy (ICP-AES). SEM analysis revealed the patchy and distributed floccules on Fe-flocs, which was an indication of multiple mechanisms responsible for Fe removal onto MCNC. A shift in the peak position attributed to C2H192N64O16 from 2θ = 30 to 24.5° occurred in the XRD pattern of both Pb- and Cu-flocs. Different process variables, including initial metal ions concentration (10–200 mg/L), solution pH (2–10), and temperature (25–45 °C) were studied in order to investigate how they affect the reaction process. Both Cu and Pb adsorption followed the Langmuir isotherm with a maximum adsorption capacity of 111.1 and 2.82 mg/g, respectively, whereas the adsorption of Fe was suggestive of a multilayer adsorption process; however, Fe Langmuir maximum adsorption capacity was found to be 81.96 mg/g. The sequence of trace metals removal followed the order: Cu > Fe > Pb. The utilization of this product in different water matrices is an effective way to establish their robustness.


2021 ◽  
Vol 15 (2) ◽  
pp. 131-144
Author(s):  
Chunjiang Jin ◽  
Huimin Chen ◽  
Luyuan Wang ◽  
Xingxing Cheng ◽  
Donghai An ◽  
...  

In this study, aspen wood sawdust was used as the raw material, and Fe(NO3)3 and CO2 were used as activators. Activated carbon powder (ACP) was produced by the one-step physicochemical activation method in an open vacuum tube furnace. The effects of different mass ratios of Fe(NO3)3 and aspen wood sawdust on the pore structure of ACP were examined under single-variable experimental conditions. The mass ratio was 0–0.4. The detailed characteristics of ACP were examined by nitrogen adsorption, scanning electron microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy. The adsorption capacity of ACP was established by simulating volatile organic compounds (VOCs) using ethyl acetate. The results showed that ACP has a good nanostructure with a large pore volume, specific surface area, and surface functional groups. The pore volume and specific surface area of Fe-AC-0.3 were 0.26 cm3/g and 455.36 m2/g, respectively. The activator played an important role in the formation of the pore structure and morphology of ACP. When the mass ratio was 0–0.3, the porosity increased linearly, but when it was higher than 0.3, the porosity decreased. For example, the pore volume and specific surface area of Fe-AC-0.4 reached 0.24 cm3/g and 430.87 m2/g, respectively. ACP presented good VOC adsorption performance. The Fe-AC-0.3 sample, which contained the most micropore structures, presented the best adsorption capacity for ethyl acetate at 712.58 mg/g. Under the action of the specific reaction products nitrogen dioxide (NO2) and oxygen, the surface of modified ACP samples showed different rich C/O/N surface functional groups, including C-H, C=C, C=O, C-O-C, and C-N.


DYNA ◽  
2016 ◽  
Vol 83 (196) ◽  
pp. 223-228 ◽  
Author(s):  
Jhonnathan Machado-Infante ◽  
Gustavo Ramírez-Caballero ◽  
Martha Juliana Barajas Meneses

<p>In Colombia, a mineral rich in MnO<sub>2</sub> is extracted from the mines of Mallama, Nariño. In this work we studied the adsorption capacity of this mineral for Fe(II) dissolved in aqueous solution of open systems. The characterization was done through ICP-AES, XRF and Raman spectroscopy. The effect of different pretreatments on the mineral with oxidizing agents such as KMnO<sub>4</sub> and NaClO was evaluated. Studies of equilibrium and kinetics of adsorption showed that the mechanism fits well to the Langmuir isotherm and its kinetics to a model of pseudo-second order. At the conditions studied was found that the adsorption capacity for the mineral modified with KMnO<sub>4</sub> and NaOCl were 59.209 and 51.279 mg/g respectively. It is concluded that the mineral is a potential alternative in water treatment.</p>


2017 ◽  
Vol 82 (4) ◽  
pp. 449-463 ◽  
Author(s):  
Sanja Marinovic ◽  
Marija Ajdukovic ◽  
Natasa Jovic-Jovicic ◽  
Tihana Mudrinic ◽  
Bojana Nedic-Vasiljevic ◽  
...  

Bentonites from three different deposits (Wyoming, TX, USA and Bogovina, Serbia) with similar cation exchange capacities were sodium enriched and tested as adsorbents for Sr2+ in aqueous solutions. X-Ray diffraction analysis confirmed successful Na-exchange. The textural properties of the bentonite samples were determined using low-temperature the nitrogen physisorption method. Significant differences in the textural properties between the different sodium enriched bentonites were found. Adsorption was investigated with respect to adsorbent dosage, pH, contact time and the initial concentration of Sr2+. The adsorption capacity increased with pH. In the pH range from 4.0?8.5, the amount of adsorbed Sr2+ was almost constant but 2?3 times smaller than at pH ?11. Further experiments were performed at the unadjusted pH since extreme alkaline conditions are environmentally hostile and inapplicable in real systems. The adsorption capacity of all the investigated adsorbents toward Sr2+ was similar under the investigated conditions, regardless of significant differences in the specific surface areas. It was shown and confirmed by the Dubinin?Radushkevich model that the cation exchange mechanism was the dominant mechanism of Sr2+ adsorption. Their developed microporous structures contributed to the Sr2+ adsorption process. The adsorption kinetics obeyed the pseudo-second-order model. The isotherm data were best fitted with the Langmuir isotherm model.


Author(s):  
Sоfiia Haidash ◽  
◽  
Viktor Kostenko ◽  

Introduction. In the process of coal mining and beneficiation, a large amount of wastewater is formed at enterprises. Sewage has a variety of origins, which can be classified into: natural (mine, quarry, drainage); technological (water for carrying out technological process, water for cooling of cars and devices); surface (water from rain, snow and maintenance of the enterprise); household (water is formed from showers, bathrooms, dining rooms). Wastewater from mines and factories is highly polluted and can have toxic effects on the environment. Problem Statement. Natural waters have a high rate of mineralization, salts of heavy metals, iron. Waters are polluted with organic matter, large and small particles of coal and rock. Surface and process effluents are contaminated with coal dust and petroleum products. Domestic waters are contaminated with surfactants, fats, animal and plant food residues, alkali, cadmium, nickel. Purpose. The aim is to study in detail the sources of pollution of mine effluents, to determine their composition and properties. Identify the seasonality of sources. Describe the method of water treatment and suggest possible improvements to existing technology. Materials and methods. The water must undergo some purification before it enters the environment. One of the main processes of wastewater treatment is filtration. This process is the most common and effective, so it should be part of the cleaning technology. The filter element can be a thin partition with pores or three-dimensional elements with a porous filler. This paper presents a technology with a granular filter, also called fast. The fast filter works on the principle of volume filtration, impurities are retained in the entire volume of the filter medium, in the pores and on the surface of the grains. Before filtration, the water is treated with coagulants. Types of granular materials: quartz sand, anthracite, expanded clay, expanded polystyrene, ceramic sand, mesoporous coal. Mesoporous coal is a promising material for filtration. Results. In the result of consideration of the composition and properties of wastewater, the appropriate technological scheme of mine wastewater treatment is selected and described. The technology provides purification from large impurities in open hydrocyclones, water treatment with flocculant, provides a filter and clarifier, enhanced purification from petroleum products in the oil trap and carbon filter. Filling the filter is sent to the coal warehouse, which is a cost-effective solution. Conclusions. The effluents of mining enterprises are saturated with pollutants and have a very aggressive composition, so it is unacceptable to release them into the environment without prior lighting. Should attention be paid to the purification of petroleum products that fall into the water as a result of the operation of machines and devices. As one of the possible methods, the technological scheme, improved by the department with oil trap and filter, is presented. Filter backfill is mesoporous coal, which is a very promising sorbent. Water treated with this technology can be used for recirculating water supply. This is justified not only by the economic aspect, but also by the environmental one. Keywords: mine drains, mining, pollution, petroleum products, filtration, technological scheme.


1992 ◽  
Vol 35 (1-2) ◽  
pp. 87-92
Author(s):  
Alfredo Donati ◽  
Manfred Sietz ◽  
Luciano Morselli ◽  
Sergio Zappoli ◽  
Andrea Gheduzzi

2008 ◽  
Vol 368-372 ◽  
pp. 1541-1544 ◽  
Author(s):  
Hua Lei Zhou ◽  
Dong Yan Li ◽  
Guo Zhuo Gong ◽  
Ya Jun Tian ◽  
Yun Fa Chen

Activated carbon was employed as the adsorption carrier for the metal ions in HCl solution of red mud, a solid waste produced in alumina industry. To improve the adsorption capacity to valuable metal ions, the activated carbon was modified by chemicals including HNO3, H2O2, H2SO4, H3PO4, NH3, Na2CO3, and tri-butyl phosphate (TBP). It was found that the modifications contributed the high adsorption capacity to almost all metal ions we focused on. In the case of TBP, remarkably higher adsorption capacity and selectivity of Sc3+ was observed. The correlation between the surface areas, IR spectra of those chemically modified activated carbons and adsorption was schemed.


2011 ◽  
Vol 410 ◽  
pp. 220-223
Author(s):  
Kwannate Sombatsompop ◽  
Thun Jeensawak ◽  
Pongsachan Sonpai ◽  
Adithep Wangbooncong ◽  
Jeatana Wongwichien ◽  
...  

This work studied an adsorption of ammonium sulfate (NH4)2SO4 from synthesized zeolite, with 3M NaOH at temperature of 90°C for 9 h, from waste sludge of water treatment plant. The scanning electron microscopic analysis revealed that the synthesized zeolite was observed to be cubic in shape. For adsorption capacity, the pH was varied at 4, 5, 6, 7 and 8, the contact times used were 0, 5, 10, 15, 30, 45 and 60 min, and the initial (NH4)2SO4 concentrations used ranged from 60-120 mg/L. The recommended pH and contact time were 8 and 15 min, respectively. Adsorption isotherm for synthesized zeolite was fitted to Langmuir model more effectively than Freundlich model. The K values for Langmuir and Freundlich isotherm was 0.061 and 1.751 L/mg with R2 values of 0.989 and 0.965, respectively. The maximum adsorption capacity was 9.597 mg/g obtained by the Langmuir isotherm. The work has concluded that the fabricated zeolite could successfully be used for adsorption of ammonium sulfate.


2019 ◽  
Vol 5 (3) ◽  
pp. 609-617 ◽  
Author(s):  
Yifeng Huang ◽  
Zhijie Nie ◽  
Jie Yuan ◽  
Audrey Murray ◽  
Yi Li ◽  
...  

A test was developed to measure the present-day adsorptive capacity of granular activated to help drinking water treatment professionals to determine when the GAC needs replacement.


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