A novel magnetic biochar efficiently sorbs organic pollutants and phosphate (original) (raw)
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Modified Biochar—A Tool for Wastewater Treatment
Energies
Global deposits of concentrated phosphates, which are a necessary source for the production of phosphate fertilizers, are limited. These reserves keep getting thinner, and every day, large amounts of phosphorus end up in watercourses. In this study, we verified that modified biochar (saturated with FeCl3 solution and then neutralized with NaOH solution) can adsorb significant amounts of phosphorus from wastewater. Moreover, the agrochemical qualities of sludge water from a municipal wastewater treatment plant, struvite, phosphorus-saturated biochar, and iron(III) phosphate from a reused biochar filter were tested in this study. We determined the amount of mobile phosphorus as well as the amount of extractable phosphorus and its five fractions. It was found that modified biochar can hold one-third of the phosphorus amount contained in the commonly used agricultural fertilizer simple superphosphate (1 × 105 g of modified biochar captures up to 2.79 × 103 g of P). Moreover, plants can ...
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.
Magnetically modified biochar for organic xenobiotics removal
Water Science and Technology, 2016
Large amounts of biochar are produced worldwide for potential agricultural applications. However, this material can also be used as an efficient biosorbent for xenobiotics removal. In this work, biochar was magnetically modified using microwave-synthesized magnetic iron oxide particles. This new type of a magnetically responsive biocomposite material can be easily separated by means of strong permanent magnets. Magnetic biochar has been used as an inexpensive magnetic adsorbent for the removal of water-soluble dyes. Five dyes (malachite green, methyl green, Bismarck brown Y, acridine orange and Nile blue A) were used to study the adsorption process. The dyes adsorption could be usually described with the Langmuir isotherm. The maximum adsorption capacities reached the value 137 mg of dye per g of dried magnetically modified biochar for Bismarck brown Y. The adsorption processes followed the pseudo-second-order kinetic model and the thermodynamic studies indicated spontaneous and end...
Reactivity of Fe-amended biochar for phosphorus removal and recycling from wastewater
PLOS Water
Using biochar to remove phosphorus (P) from wastewater has the potential to improve surface water quality and recycle recovered P as a fertilizer. In this research, effects of iron modification on P sorption behavior and molecular characterization on two different biochars and an activated carbon were studied. A biochar produced from cow manure anaerobic digest fibers (AD) pyrolyzed under NH3 gas had the greatest phosphate sorption capacity (2300 mg/kg), followed by the activated carbon (AC) (1500 mg/kg), and then the biochar produced from coniferous forest biomass (BN) (300 mg/kg). Modifying the biochars and AC with 2% iron by mass increased sorption capacities of the BN biochar to 2000 mg/kg and the AC to 2300 mg/kg, but decreased sorption capacity of the AD biochar to 1700 mg/kg. Molecular analysis of the biochars using P K-edge X-ray absorption near edge structure (XANES) spectroscopy indicated that calcium phosphate minerals were the predominant species in the unmodified biocha...
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.
The Science of the total environment, 2017
Despite the excellent sorption ability of biochar for heavy metals, it is difficult to separate and reuse after adsorption when applied to wastewater treatment process. To overcome these drawbacks, we developed an engineered magnetic biochar by pyrolyzing waste marine macro-algae as a feedstock, and we doped iron oxide particles (e.g., magnetite, maghemite) to impart magnetism. The physicochemical characteristics and adsorption properties of the biochar were evaluated. When compared to conventional pinewood sawdust biochar, the waste marine algae-based magnetic biochar exhibited a greater potential to remove heavy metals despite having a lower surface area (0.97m(2)/g for kelp magnetic biochar and 63.33m(2)/g for hijikia magnetic biochar). Although magnetic biochar could be effectively separated from the solution, however, the magnetization of the biochar partially reduced its heavy metal adsorption efficiency due to the biochar's surface pores becoming plugged with iron oxide p...
Bioresource technology, 2016
The present study deals with the preparation of a novel MgO-impregnated magnetic biochar (MMSB) for phosphate recovery from aqueous solution. The MMSB was evaluated against sugarcane harvest residue biochar (SB) and magnetic biochar without Mg (MSB). The results showed that increasing Mg content in MMSB greatly improved the phosphate adsorption compared to SB and MSB, with 20% Mg-impregnated MMSB (20MMSB) recovering more than 99.5% phosphate from aqueous solution. Phosphate adsorption capacity of 20MMSB was 121.25mgP/g at pH 4 and only 37.53% of recovered phosphate was desorbed by 0.01mol/L HCl solutions. XRD and FTIR analysis showed that phosphate sorption mechanisms involved predominately with surface electrostatic attraction and precipitation with impregnated MgO and surface inner-sphere complexation with Fe oxide. The 20MMSB exhibited both maximum phosphate sorption and strong magnetic separation ability. Overall, phosphate-loaded 20MMSB significantly enhanced plant growth and c...
Production of magnetic biochar from waste-derived fungal biomass for phosphorus removal and recovery
Journal of Cleaner Production, 2019
This study presents a new bottom-up biofabrication method to produce highly porous magnetic biochar from waste-derived fungal biomass. Neurospora crassa was grown in iron containing coagulation backwash (BW) diluted with primary effluent (PE) wastewater in two ratios of 1:4 (PE-BW 1:4) and 3:4 (PE-BW 3:4). The fungi encapsulated iron directly into biomass hyphae and carbonization resulted in one-step biochar preparation and maghemite (Fe 2 O 3) formation. The morphology and structure of the materials were investigated using a suite of characterization tools. Results indicated that the physiochemical properties of each char were dependent on the blend used for fungal cultivation. PE-BW 1:4 had much larger average pore diameters (13.
Arabian Journal of Geosciences, 2019
This study was aimed to enhance the phosphorus (P) sorption capability of biochar through embedding of Mg-Fe layered double hydroxide (LDH) particles within its matrix. The structure, morphology, and surface chemistry of the prepared LDH/biochar composite were investigated via X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and Fourier transform infrared (FTIR) analysis. The P sorption behavior of LDH/biochar composite was assessed in comparison with the raw biochar under batch conditions. The effects of initial P concentrations, pH levels, and contact times on P sorption were examined. Results showed that the P sorption on LDH/biochar composite was pH-dependent, and the maximum P sorption was found at the pH range of 2-4. The sorption isotherm and kinetic data were best fitted with the Langmuir and pseudosecond-order models, respectively. The maximum P sorption capacity (Q max) improved from 1.39 mg g −1 for raw biochar to 17.46 mg g −1 for LDH/biochar composite, respectively. Also, the equilibrium contact time decreased from 8 h for raw biochar to 1 h for LDH/biochar composite, respectively. The sorption process followed electrostatic attraction, ligand exchange, and surface inner-sphere complex formation mechanisms. Overall, the results of the present study revealed that the synthesized LDH/biochar composite can be potentially used as a carbon-based sorbent for the removal of phosphorus from aqueous solutions.
Use of three types of magnetic biochar in the removal of copper(II) ions from wastewaters
Separation Science and Technology, 2017
Three types of magnetic biochars (MBC1, MBC2 and MBC3) were synthesized from biochar using NaBH 4 as a reducing agent of Fe(II) to Fe(0) to remove copper(II) ions from different wastewaters. Based on the research it was found that removal of copper(II) ions by MBC1 occurs with a yield of 99.8% for the concentration 50 mg/dm 3 and decreases to 71.7% at 200 mg/dm 3. The maximum pH sorption was found at pH 5. The highest correlation coefficient values (65.55 mg/g) were obtained for the Langmuir isotherm model. Application of 0.5 mol/dm 3 HNO 3 as a desorbing agent gives the highest desorption percentage 98.92%.