Preparation and Characterization of Novel Magnesium Composite/Walnut Shells-Derived Biochar for As and P Sorption from Aqueous Solutions

Abstract

Elevated or unnatural levels of arsenic (As) and phosphorus (P) concentrations in soils and waterbodies from anthropogenic sources can present significant hazards for both natural ecosystems and human food production. Effective, environmentally friendly, and inexpensive materials, such as biochar, are needed to reduce mobility and bioavailability of As and P. While biochar features several physicochemical properties that make it an ideal contaminant sorbent, certain modifications such as mineral-impregnation can improve sorption efficiencies for targeted compounds. Here, we conducted sorption experiments to investigate and quantify the potential utility of magnesium (Mg) for improving biochar sorption efficiency of P and As. We synthesized a Mg-modified walnut shells-derived biochar and characterized its ability to remove As and P from aqueous solutions, thereby mitigating losses of valuable P when needed while, at the same time, immobilizing hazardous As in ecosystems. SEM-EDX, FTIR and elemental analysis showed morphological and functional changes of biochar and the formation of new Mg-based composites (MgO, MgOHCl) responsible for improved sorption potential capacity by 10 times for As and 20 times for P. Sorption efficiency was attributed to improved AEC, higher SSA, chemical forms of sorbates and new sorption site formations. Synthetized Mg-composite/walnut shell-derived biochar also removed >90% of P from real samples of wastewater, indicating its potential suitability for contaminated waterbody remediation.

Effects of Composts Made from Broiler Chicken Residues and Blended with Biochar on the Minerals and Phenolic Compounds in Parsley (Petroselinum crispum Mill.)

“…However, the highest yields were obtained with the sawdust-chicken composed substrate. These data demonstrate that the ability to manipulate composts and biochar, as well as cultivation parameters, can help meet specific yield and quality goals [6]. Related to quality, there is a clear need to generate a robust understanding of the mechanisms by which organic amendments affect nutrients and bioactive compounds in crops.…”

“…The chromatographic peaks obtained were identified by comparing the elution profiles to those reported by [21], under the same conditions of extraction and using the same instrumentations, and those reported by [30], who studied phenolics in parsley grown on a tree-chicken compost supplemented with biochar, similar to treatment T45 in this study. Using these criteria, the following six compounds were identified with some certainty: apigenin-7-apiosylglucoside (apin) (1), diosmetin-apiosylglucoside (2), diosmetin-apiosylglucoside isomer (3), apigeninmalonyl-apiosylglucoside (malonyl apin) (4), diosmetin-malonyl-apiosylglucoside (5), and apigenin-malonylglucoside (6). The compounds were quantified using a regression curve of six concentrations of apigenin (R 2 ≥ 0.962).…”

“…High yields were obtained with the bagasse-chicken substrates; however, these yields were only obtained at high biochar proportions: B45 (27.91 g pot −1 ), B30 (25.26 g pot −1 ), and B60 (25.12 g pot −1 ). A key physical feature of biochar is its highly porous structure and large surface area [3,6,12]. This structure can provide for efficient diffusion of nutrients.…”

“…However, a positive relationship was found between the substrate P and the parsley P contents for B00, S00, and T00 (Table 1; Table 2). These results could be explained by the relative proportions of the different types of P present in the substrates, which determines the overall availability of phosphorus [6,38,39].…”

“…As a result, the composition of the growing medium of greenhouse-grown plants must be optimized to sustain and nourish the plants. Several organic media/substrates for growing plants, including composts, peat, expanded clay, bark, coir, perlite, and vermiculite have been evaluated by different researchers [3][4][5][6]. Composting aids in the recovery of nutrients and other organic compounds from organic wastes, thereby increasing their availability to plants.…”