Bio-assembled MgO-coated tea waste biochar efficiently decontaminates phosphate from water and kitchen waste fermentation liquid

Abstract

Crystal morphology of metal oxides in engineered metal-biochar composites governs the removal of phosphorus (P) from aqueous solutions. Up to our best knowledge, preparation of bio-assembled MgO-coated biochar and its application for the removal of P from solutions and kitchen waste fermentation liquids have not yet been studied. Therefore, in this study, a needle-like MgO particle coated tea waste biochar composite (MTC) was prepared through a novel biological assembly and template elimination process. The produced MTC was used as an adsorbent for removing P from a synthetic solution and real kitchen waste fermentation liquid. The maximum P sorption capacities of the MTC, deduced from the Langmuir model, were 58.80 mg g−1 from the solution at pH 7 and 192.8 mg g−1 from the fermentation liquid at pH 9. The increase of ionic strength (0–0.1 mol L−1 NaNO3) reduced P removal efficiency from 98.53% to 93.01% in the synthetic solution but had no significant impact on P removal from the fermentation liquid. Precipitation of MgHPO4 and Mg(H2PO4)2 (76.5%), ligand exchange (18.0%), and electrostatic attraction (5.5%) were the potential mechanisms for P sorption from the synthetic solution, while struvite formation (57.6%) and ligand exchange (42.2%) governed the sorption of P from the kitchen waste fermentation liquid. Compared to previously reported MgO-biochar composites, MTC had a lower P sorption capacity in phosphate solution but a higher P sorption capacity in fermentation liquid. Therefore, the studied MTC could be used as an effective candidate for the removal of P from aqueous environments, and especially from the fermentation liquids. In the future, it will be necessary to systematically compare the performance of metal-biochar composites with different metal oxide crystal morphology for P removal from different types of wastewater. Graphical Abstract

Modified Biochars Reduce Leaching while Maintaining Bioavailability of Phosphate to Dragoon Lettuce (Lactuca sativa) in Potting Tests

“…Previous studies of ours and others have found that magnesium oxide-doped biochar, made by pyrolyzing biomass impregnated with a magnesium salt, can strongly sorb phosphate. ,− The bound phosphate is coordinated to Mg and shows appreciable resistance to displacement by common anions and organic matter in soil pore water . In addition, we demonstrated that postpyrolysis treatment of biochar with the quaternary ammonium cationic polymer, poly­(diallyldimethylammonium) chloride (pDADMAC), is capable of strongly sorbing phosphate via anion exchange.…”

Myriophyllum Biochar-Supported Mn/Mg Nano-Composites as Efficient Periodate Activators to Enhance Triphenyl Phosphate Removal from Wastewater

“…On the other hand, the C-O peak intensity of Mn/Mg@MV is significantly weakened compared with that of MV, while the peak representing the metal oxide peak at Mn-O and Mg-O (482 cm −1 ) [ 23 ] is significantly enhanced, which proves the successful deposition of the metal elements Mn and Mg. This is further illustrated by the significant shift in the -OH peak [ 48 ], where Mn and Mg replaced part of the -OH and -CO functional groups and formed Mn-O and Mg-O functional groups. This suggests that Mn and Mg are not simply loaded on the surface of the biochar but are bonded through stable chemical bonds.…”

Removing Norfloxacin from Aqueous Solutions Using Biochar Derived from Waste Disposable Bamboo Chopsticks

“…At present, the common physical and chemical treatment methods for NOR and other antibiotics include membrane filtration [7,8], advanced oxidation [9,10], and adsorption [11,12]. Compared to the other two methods, the adsorption method has the advantages of being economically feasible, easily carried out, and environmentally friendly [13,14]. The adsorbent used is a major factor that affects the process of adsorption.…”