Recovery of phosphate from aqueous solution by magnesium oxide decorated magnetic biochar and its potential as phosphate-based fertilizer substitute (original) (raw)
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Iron and Magnesium Impregnation of Avocado Seed Biochar for Aqueous Phosphate Removal
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There has been increasing interest in using biochar for nutrient removal from water, and its application for anionic nutrient removal such as in phosphate (PO43−) necessitates surface modifications of raw biochar. This study produced avocado seed biochar (AB), impregnated Fe- or Mg-(hydr)oxide onto biochar (post-pyrolysis), and tested their performance for aqueous phosphate removal. The Fe- or Mg-loaded biochar was prepared in either high (1:8 of biochar to metal salt in terms of mass ratio) or low (1:2) loading rates via the co-precipitation method. A total of 5 biochar materials (unmodified AB, AB + High Fe, AB + Low Fe, AB + High Mg, and AB + Low Mg) were characterized according to their selected physicochemical properties, and their phosphate adsorption performance was tested through pH effect and adsorption isotherm experiments. Fe-loaded AB contained Fe3O4, while Mg-loaded AB contained Mg(OH)2. The metal (hydr)oxide inclusion was higher in Fe-loaded AB. Mg-loaded AB showed a u...
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The large production volume combined with the high lignocellulose content makes elephant dung an attractive and underutilized biomass resource, but also presents waste management problems for elephant orphanages. This study explored the conversion of elephant dung into biochars by slow pyrolysis at 500°C for the recovery of phosphate. The unmodified biochar (BC500) had a specific surface area (SBET) of 62.5 m2×g-1 with point of zero charge (pHPZC) of 7.7. Biochar modification with MgCl2 (MgBC500) and FeCl3 (FeBC500) by pre-pyrolysis treatment affected the SBET (48.7 m2×g-1 and 259.4 m2×g-1, respectively) and pHPZC (8.7 and 3.3, respectively). In FeBC500, Fe was present as magnetite (Fe3O4) and hematite (α-Fe2O3) as confirmed by X-ray diffraction. Instead of adsorption, both BC500 and MgBC500 released phosphate at pH 3-6. Phosphate adsorption onto FeBC500 reached equilibrium within 24 h and followed pseudo-second order kinetics. The adsorption isotherm was best described with the Lan...
Journal of Water Process Engineering, 2021
The present study is conducted to synthesize vinasse-derived biochar, followed by modification with Micro and Nano MgO in an attempt to assess their effects on the phosphate (P) removal from aqueous medium. Based on the characterization results of modified biochars and adsorption capacities, Nano-MgO Functionalized ones have proven to be more capable in P removal, with the specific surface areas of 119.98-125.41 m 2 /g and maximum P adsorption capacity of 188.67 mg/g. The dependencies of adsorption on initial P concentration (50-350 mg/L), contact time (5-90 min), and solution pH level (3-11) were investigated by 20 experiments designed via CCDbased RSM. The regression analysis showed a good fit of the experimental data to the second-order polynomial model with coefficient of determination (R 2) value of 0.9916 and model F-value of 131.82. The optimum conditions of pH (7.00), contact time (75 min), and initial P concentration (250 mg/L) were recorded from desirability function. Based on the thermodynamic analysis, the adsorption process was spontaneous and exothermic in nature. In addition, the isotherm and kinetic studies indicated that the Freundlich and the pseudo-second order are the best fitted models for the P adsorption. Further, the P removal efficiency declined slightly in the presence of other co-existed anions, while acted relatively selective towards P. Finally, the P-loaded biochar could be properly regenerated by 1.0 M HCl solution, and the pot experiments proved its applicability as a P fertilizer substitute, increasing the plant growth rateaveragely, the height by 40 % and the dry mass by 59 %.
A novel magnetic biochar efficiently sorbs organic pollutants and phosphate
Bioresource technology, 2011
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Environmental Nanotechnology, Monitoring & Management, 2023
Excessive phosphorous discharge causes eutrophication of the aquatic system. Hence, from the viewpoints of eutrophication control and sustainable use of phosphorous, its recovery from wastewater is essential. Herein, Mg/Zr modified nanobiochar from spent coffee grounds (Mg/Zr/CNBC) is reported as an efficient adsorbent for phosphate recovery, and phosphorous release fertilizer. SEM, XRD, and FTIR characterizations of the adsorbent before and after adsorption suggested that phosphate is involved in both physisorption and chemisorption. Adsorption of phosphate on Mg/Zr/CNBC and factors affecting the process viz pH, contact time, initial phosphate concentrations, and dose of adsorbent were investigated in batch mode experiments. Mg/Zr/CNBC showed a 23.36 and 11.84 % improvement in the adsorption efficiency than the pristine and Mg-modified nanobiochar respectively. Acidic conditions favored the adsorption of phosphate on Mg/Zr/CNBC with maximum adsorption (98.5 %) at pH 1. Adsorption of phosphate followed pseudo-second-order kinetics. The corresponding equilibrium constant (K 2) and adsorption capacity were calculated to be 0.316 g/mg. min and 39.4 mg/g respectively. The equilibrium data obtained at different phosphate concentrations better fitted the Freundlich adsorption isotherm model (R 2 = 0.998) suggesting multilayer adsorption of phosphate on a heterogeneous surface. Further, the utility of phosphate-laden Mg/Zr/CNBC as a phosphorous-release fertilizer was demonstrated in a pot test. Results of the pot test showed that phosphate-laden Mg/Zr/CNBC improved the growth of Wheat and Chickpeas by 31.16 and 29.63 % respectively. The result highlights a circular economy approach for spent coffee grounds.
Alexandria Science Exchange Journal, 2018
Utilization of agricultural wastes to generate cheap and efficient sorbents to remove contaminants from wastewaters is an up-to-date environmental challenge. In Egypt, sugarcane bagasse is yearly generated as a waste material in huge amounts. The objectives of this study were to investigate the effect of chemical modification on the properties of bagasse biochar generated from local sugarcane bagasse feedstock (SCBF) and assess its efficiency for removal of both ammonium and phosphate ions from artificial aqueous solutions. SCBB and Mg-SCBB biochars were produced through pyrolysis of raw SCBF and MgSO 4 impregnated SCBF, respectively at 500 C and under oxygen-limited condition. FTIR peaks analysis, DEM examination, and some physical and chemical properties revealed that new surface functional groups, meso-and micropores, larger surface area and higher CEC were developed in SCBB and Mg-SCBB compared to SCBF. SCBB and Mg-SCBB showed high affinity to ammonium adsorption from aqueous solutions comparable to Charcoal and Zeolite. Mg-SCBB was the only sorbent capable of removing phosphate from the aqueous. Ammonium and phosphate removal at 1:200 sorbent to solution ratio were higher than those at 1:500 for all sorbents. A slight ammonium volatilization occurred during the adsorption process due to high solution pH. Adsorption kinetics data were best fitted to the pseudo-second-order kinetic equation suggesting intraparticle diffusion controlled adsorption process. Ammonium adsorption isotherms were best fitted to Freundlich model. The calculated Freundlich intensity parameter (n) ranged from 0.478 to 0.894 indicating favorable adsorption of ammonium and phosphate by all sorbents. Mg-SCBB had an adsorption capacity of 2573.9 and 4002.2 mg kg-1 for ammonium and phosphate, respectively. The produced Mg-modified sugarcane bagasse biochar may represent a promising efficient and cheap sorbent for dual remediation of wastewaters contaminated with ammonium and phosphate ions.
Novel Fe/Ca oxide co-coated biochar enables efficient phosphorus recovery
Research Square (Research Square), 2024
Efficient elimination and retrieval of phosphorus from water bodies are crucial for effective eutrophication management and phosphorus reuse. A novel Fe/Ca oxide co-coated modified biochar (FCBC) was synthesized for phosphate recovery using coconut shell biochar as the raw material with ferrous chloride (FeCl2) and calcium peroxide (CaO2) as precursors. FCBC possesses a highly intricate pore structure and an abundance of surface-active groups. Fe/Ca oxides are loaded onto the biochar in the form of Ca2Fe2O5, Fe2O3, and CaCO3. FCBC demonstrates a broad pH tolerance range (pH = 6-12) in the aquatic environment. Phosphorus absorption by FCBC was simulated using the proposed pseudo-second-order kinetic and Langmuir model. The maximal saturation adsorption capacity was found to be 53.31 mg P/g. Phosphorus elimination is influenced by the generation of Ca3(PO4)2, intraparticle diffusion, and electrostatic attraction. FCBC produced demonstrated exceptional phosphorus removal effectiveness in the presence of multiple anions, except for wastewater with high concentrations of SO4 2-, CO3 2-, HCO3-, and F-(>500 mg/L). The phosphorus removal effectiveness of FCBC in natural water samples collected from ponds, farmlands, and ditches exceeded 94%. This paper presents a novel technique for creating iron-calcium composite-modified biochar, which offers a valuable method for efficiently recovering phosphorus from agricultural surface waters.
Biochar
To improve the phosphorus (P) recovery efficiency from livestock wastewater, a novel MgO doped mildewed corn biochar with thermal pre-puffing treatment (Mg-PBC) and without pre-puffing (Mg-BC) was synthesized and tested. The thermal-puffing pretreatment improved the effectiveness of metal soaking and MgO dispersion. P recovery time with Mg-PBC (7 h) was significantly shorter than that with Mg-BC (12 h). Moreover, Mg-PBC showed significantly higher P recovery capacity (241 mg g−1) than Mg-BC (96.6 mg g−1). P recovery capacity of the Mg-PBC fitted to the Thomas model was 90.7 mg g−1, which was 4 times higher than that of Mg-BC (22.9 mg g−1) under column test conditions. The mechanisms involved in P recovery included precipitation, surface complexation, and electrostatic interaction. After adsorption, both Mg-BC and Mg-PBC showed relatively low regeneration abilities. The P loaded Mg-BC (Mg-BC-P) and Mg-PBC (Mg-PBC-P), the later particularly, obviously increased the available P content...
Case Studies in Chemical and Environmental Engineering
Negatively charged biochar restricts adsorbing orthophosphate anions-a main cause of eutrophication, thus modified biochar is suggested to enhance phosphate (PO 4 3-) adsorption from aqueous solution. This work tested the hypothesis that modified biochar results in the enhancement of PO 4 3adsorption compared to pristine biochar derived from Mimosa pigra. Aluminium-modified biochars with different concentrations of AlCl 3 (i.e., 0.5, 1, 2, and 3 M) and the pristine biochar were performed for absorbing PO 4 3in batch experiments. Among the modified biochars, 2 M Al-modified biochar achieved the highest PO 4 3adsorption capacity (70.6 mgPO 4 3-/g) which was 14 times greater than pristine biochar (5.1 mgPO 4 3-/g). Chemical adsorption and electrostatic attraction may control significantly to the adsorption of PO 4 3on biochars. The 2 M Al-modified biochar presents the potential adsorbent for removing phosphorus from water.
Journal of Cleaner Production, 2019
The continuous increase in the world population requires more agricultural production; therefore, phosphorus compounds (P) are essentials. Considering that P reserves are finite, studying its recycling and reusing is essential. Biochar made from agricultural residues is an interesting material to be studied for P recovery and reuse in agriculture. This study shows the preparation and characterization of a biochar obtained from the pyrolysis of carrot residue for P adsorption studies in aqueous solution. Carrot was pyrolyzed at different temperatures values, with and without pretreatment with MgCl 2. Biochar impregnated with Mg and pyrolyzed at 400°C showed higher efficiency in P removal in aqueous solution (138 mg g-1). The characterization techniques indicated that after P adsorption by biochar, a chemical reaction occurred between Mg and P species with formation of Mg(H 2 PO 4) 2. The biochar from carrot residue obtained in this work is a promising adsorbent for P recycling and has potential to be used as soil fertilizer.