Surface decoration and characterization of solar driven biochar for the removal of toxic aromatic pollutant (original) (raw)
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Lead sorptive removal using magnetic and nonmagnetic fast pyrolysis energy cane biochars
Journal of Colloid and Interface Science, 2014
Energy cane biochar (ECBC) was prepared in a 72 s fast pyrolysis at 425°C in an auger-fed reactor and ground into 250-600 lm diameter particles. This biochar was magnetized by fusing an iron oxide phase to the particles by mixing aqueous biochar suspensions with aqueous Fe 3+ /Fe 2+ solutions, followed by NaOH treatment (MECBC). These biochars were characterized by Raman, FT-IR, X-ray, SEM, SEM-EDX, TEM, EDXRF, pHzpc, elemental analyses, S BET , and magnetic moment determinations. The S BET of energy cane biochar was negligible and increased to 37.13 m 2 /g after Fe 3+ /Fe 2+ /NaOH magnetization. The dry biochar contains 18.4% oxygen. This allows swelling in water and permits sorption inside the solid as well as on its pore surfaces, leading to high capacities at low surface areas. Maximum lead removal occurred at pH 4-5. Sorption isotherms exhibited increasing lead removal (Q 0 , mg/g) as temperature increased for nonmagnetic [Q 0 25°C = 45.70; Q 0 35°C = 52.01 and Q 0 45°C = 69.37] and magnetic [Q 0 25°C = 40.56; Q 0 35°C = 51.17 and Q 0 45°C = 51.75] biochars. Second order kinetics best fit the lead removal data. Furthermore, magnetic energy cane biochar was easily manipulated by low external magnetic field, thereby, allowing its easy recovery for further recycling and replacement from water. ECBC and MECBC were also successfully applied for Pb 2+ removal from contaminated ground water. Therefore, both chars can be used as potential green low cost sorbents for lead remediation to replace commercial activated carbon.
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Bioresource technology, 2011
The user has requested enhancement of the downloaded file. All in-text references underlined in blue are added to the original document and are linked to publications on ResearchGate, letting you access and read them immediately. This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues.
Journal of Nanomaterials
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DESALINATION AND WATER TREATMENT
In this study, engineered (chemically modified) biochars (pyrolyzed bamboo biomass) were used for the removal of oxidized and reduced nitrogen species from an aqueous solution. The physicochemical properties of the prepared materials, such as surface functional groups, elemental composition, morphology, and specific surface area were investigated. The biochar surfaces were covered with Mg and Fe particles. The particles containing Mg and Fe species were observed in the form of nanoflakes within the biochar matrix. The efficiency of nitrate and ammonium removal was examined by sorption studies. The experimental data were fitted with sorption isotherms (Langmuir, Freundlich, and Dubinin-Raduskievich) and with kinetic models. The obtained data presented a higher sorption capacity for nitrate removal in the case of the engineered Fe-biochar and the engineered Mg-biochar compared to unmodified bamboo-based biochar. The maximum sorption capacity of modified samples decreased in the order Fe-biochar (Q e = 10.35 mg g-1), Mg-biochar (Q e = 9.13 mg g-1), and the lowest capacity was found in the unmodified biochar (Q e = 4.41 mg g-1). In the case of ammonium removal, unmodified biochar with maximum sorption capacity (Q e = 12.60 mg g-1), was more efficient than Fe-(Q e = 5.66 mg g-1), and Mg-engineered biochars (Q e = 3.23 mg g-1). The pseudosecond-order kinetic model and Langmuir isotherm model proved to be the most appropriate for the experimental sorption data. In addition, engineered Fe-biochar presented magnetic properties due to the presence of Fe 2 O 3 and therefore, may be easily separated from the reaction mixtures.
Research article, 2019
Water purification is slowly becoming a problem worldwide due to population growth. Lack of proper wastewater disposal from domestic and industrial sources has escalated water pollution in developing countries. Continuous pollution of water sources has made water purification for domestic supplies very expensive. Modern and cost-effective ways of water purification are urgently needed. One of the modern emerging technologies is adsorption using nano-materials. The aim of the study was to prepare an engineered iron oxide-biochar (Fe 2 O 3-BC), a nano-composite using pyrolysis and microwave activation. The efficiency of the nano-composite was evaluated in the removal of the heavy metal lead (Pb) and the dye methyl orange (MO) in aqueous solutions. Infrared spectroscopy was used to identify the functional groups present in the synthesized biochars before and after adsorption. The adsorption properties of the synthesised Original Research Article Shumba et al.; JMSRR, 4(3): 1-12, 2019; Article no.JMSRR.52734 2 Fe 2 O 3-BC and biochar (BC) were determined by application in lead metal and methyl orange aqueous solutions on known concentrations. FAAS and UV/VIS Spectrophotometry were used for Lead and Methyl Orange concentrations measurements respectively. Batch adsorption experiments were conducted to investigate the capacity of Fe 2 O 3-BC and BC to remove MO and Pb in aqueous solutions. A dose of 50 mg Fe 2 O 3-BC had the highest percentage MO removal of 89.81% at pH 2 while 50 mg of BC had a highest of 11.55% at pH 12. A dosage of 100 mg of Fe 2 O 3-BC had 100% MO removal and 250 mg BC achieved a maximum of 30.61% removal in 30 minutes. Maximum MO removal concentrations were 70 mg/L and 55 mg/L respectively for Fe 2 O 3-BC and BC adsorbents. Both Fe 2 O 3-BC and BC had Pb 2+ removal of 97% in 30 minutes. A dose of 65 mg for both Fe 2 O 3-BC and BC adsorbents had 100% removal of Pb 2+. The adsorption studies of both MO dye and Pb 2+ on Fe 2 O 3-BC nano-composite fit the Langmuir isotherm (R 2 value of 0.999) and Temkin isotherm (R 2 value of 0.919). The Fe 2 O 3-BC nano-composite adsorbs Pb and MO dye better than biochar. The Fe 2 O 3-BC nano-composite could be a good adsorbent for other cations and anions. More work need to be done in order to investigate the adsorption potential of other cations and anions using Fe 2 O 3-BC nano-composite.
Bioresource technology, 2016
Modified biochar (BC) is reviewed in its preparation, functionality, applications and regeneration. The nature of precursor materials, preparatory conditions and modification methods are key factors influencing BC properties. Steam activation is unsuitable for improving BC surface functionality compared with chemical modifications. Alkali-treated BC possesses the highest surface functionality. Both alkali modified BC and nanomaterial impregnated BC composites are highly favorable for enhancing the adsorption of different contaminants from wastewater. Acidic treatment provides more oxygenated functional groups on BC surfaces. The Langmuir isotherm model provides the best fit for sorption equilibria of heavy metals and anionic contaminants, while the Freundlich isotherm model is the best fit for emerging contaminants. The pseudo 2(nd) order is the most appropriate model of sorption kinetics for all contaminants. Future research should focus on industry-scale applications and hybrid sy...
One-step microwave synthesis of magnetic biochars with sorption properties
Carbon letters, 2018
Copyright © Korean Carbon Society http://carbonlett.org Abstract Adsorption is one of the best methods for wastewater purification. The fact that water quality is continuously decreasing requires the development of novel, effective and cost available adsorbents. Herein, a simple procedure for the preparation of a magnetic adsorbent from agricultural waste biomass and ferrofluid has been introduced. Specifically, ferrofluid mixed with wheat straw was directly pyrolyzed either by microwave irradiation (900 W, 30 min) or by conventional heating (550°C, 90 min). Magnetic biochars were characterized by X-ray powder diffraction, Mössbauer spectroscopy, textural analysis and tested as adsorbents of As(V) oxyanion and cationic methylene blue, respectively. Results showed that microwave pyrolysis produced char with high adsorption capacity of As(V) (Qm= 25.6 mg g–1 at pH 4), whereas conventional pyrolysis was not so effective. In comparison to conventional pyrolysis, one-step microwave pyrol...
Investigations of Heavy Metal Ion Sorption Using Nanocomposites of Iron-Modified Biochar
Magnetic biochar nanocomposites were obtained by modification of biochar by zero-valent iron. The article provides information on the impact of contact time, initial Cd(II), Co(II), Zn(II), and Pb(II) ion concentrations, dose of the sorbents, solution pH and temperature on the adsorption capacity. On the basis of experiments, it was found that the optimum parameters for the sorption process are phase contact time 360 min (after this time, the equilibrium of all concentrations is reached), the dose of sorbent equal to 5 g/dm 3 , pH 5 and the temperature 295 K. The values of parameters calculated from the kinetic models and isotherms present the best match to the pseudo second order and Langmuir isotherm models. The calculated thermodynamic parameters ΔH 0 , ΔS 0 and ΔG 0 indicate that the sorption of heavy metal ions is an exothermic and spontaneous process as well as favoured at lower temperatures, suggesting the physical character of sorption. The solution of nitric acid(V) at the concentration 0.1 mol/dm 3 was the best acidic desorbing agent used for regeneration of metal-loaded magnetic sorbents. The physicochemical properties of synthesized composites were characterized by FTIR, SEM, XRD, XPS and TG analyses. The point characteristics of the double layer for biochar pH PZC and pH IEP were designated.
A Humins-Derived Magnetic Biochar for Water Purification by Adsorption and Magnetic Separation
Waste and Biomass Valorization, 2021
In this study, the use of magnetic biochar particles recovered from biorefinery by-products (humins) for adsorption of hydrophilic organic pollutants was investigated. The biochar was prepared by thermal treatment of crude humins followed by a grinding step after which a magnetic iron oxide was co-precipitated on the biochar surface. The resulting iron oxide content of the biochar composite was found to be 9 % by volume, and the presence of a characteristic Fe-O vibrational band was observed by FTIR-ATR. XPS analysis of Fe2p spectrum enabled the nature of iron oxide to be identified as maghemite. Finally, magnetometry measurements demonstrated the superparamagnetic properties of maghemite. The adsorption of methylene blue on the biochar composite was found to be fast (less than 1 hour at pH 6 with an initial concentration of methylene blue of 2•10-5 mol.L-1). Kinetics data were satisfactorily modelled by both first and second order models. Freundlich and Langmuir models were applied to adsorption isotherms data. Maximum adsorption capacity (3.35•10-5 mol.g-1), and Langmuir and Freundlich constants (2.33•10 4 L.mol-1 and 5.70•10-5 mol 0.913 .L 0.087 .g-1 respectively) were found to be comparable to the average of those found in the literature. Electrostatic attraction between oppositely charged methylene blue and magnetic biochar was presumed to be the dominant interaction governing adsorption at environmental pH values. Lastly, a laboratory-scale experimental device with magnetic filtration under flow allowed the complete separation of the magnetic biochar composite from the liquid phase. This study shows that this magnetic biochar composite is a promising and economically interesting recovery route for biorefinery by-products and could be used for adsorption purposes.