A new post-treatment method was applied for improving the sorption efficiency of biochar-based sorbents for anionic forms of phosphorus. The Fe-impregnation through direct hydrolysis of Fe(NO) was used to produce impregnated corn cob- (IBC A), garden wood waste- (IBC B), and wood chip-derived biochars (IBC C). The qualitative and quantitative effects of impregnation process on biochars were confirmed by SEM-EDX, FTIR, and ICP-MS. The analyses revealed increased concentrations of N and thus potential NO participation in the phosphate sorption process. Biochar surface area showed a significant decrease after the impregnation process due to the filling of micro- and mesopores with Fe maximum sorption capacity (Q ) increased by a factor of 12-50. The sorption processes of phosphates by IBC A, IBC B, and IBC C were dependent on pH, initial concentration, and time. Speciation analysis and pH-study confirmed the range of pH 4.5-5.5 as optimum values at which most of phosphorus is present in form of mononuclear HPO. Batch sorption experiments showed a significant increase in the sorption capacity for phosphates by Fe impregnation of biochar as well as effectiveness and stability of this treatment. These findings indicate an option for utilizing engineered biochars as tools for the recovery of phosphorus from the aquatic environment.

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In this work, the high temperature oxidation behavior of Al71Co29 and Al76Co24 alloys (concentration in at.%) is presented. The alloys were prepared by controlled arc-melting of Co and Al granules in high purity argon. The as-solidified alloys were found to consist of several different phases, including structurally complex m-Al13Co4 and Z-Al3Co phases. The high temperature oxidation behavior of the alloys was studied by simultaneous thermal analysis in flowing synthetic air at 773–1173 K. A protective Al2O3 scale was formed on the sample surface. A parabolic rate law was observed. The rate constants of the alloys have been found between 1.63 × 10−14 and 8.83 × 10−12 g cm−4 s−1. The experimental activation energies of oxidation are 90 and 123 kJ mol−1 for the Al71Co29 and Al76Co24 alloys, respectively. The oxidation mechanism of the Al-Co alloys is discussed and implications towards practical applications of these alloys at high temperatures are provided.

The corrosion performance of as-solidified Al-Pd alloys in HCl and NaOH aqueous solutions is investigated in this work. Four different alloys (Al 88 Pd 12 , Al 77 Pd 23 , Al 72 Pd 28 and Al 67 Pd 33 , element concentrations are given in at.%) were prepared from high purity Al and Pd lumps by arc-melting in Ar. Subsequently, the alloy microstructure and phase occurrence were investigated by a combination of scanning electron microscopy and room-temperature powder X-ray diffraction. The assolidified Al-Pd alloys were found to consist of several single-phase microstructure constituents with various structures and chemical compositions, including structurally complex intermetallic phases. The polished surfaces of the Al-Pd alloys were subjected to electrochemical polarization in aqueous HCl and NaOH solutions (0.01 mol.dm-3) at 21±2°C. The corrosion experiments were conducted in a standard 3-electrode cell controlled by potentiostat. The corrosion potentials and corrosion current densities were determined by Tafel extrapolation of the experimental polarization curves. Phase dissolution has been observed on the alloy surfaces and some of the phases were preferentially corroded. The effects of the alloy microstructure and the phase occurrence are evaluated. The local nobility of individual intermetallic compounds is discussed. Finally, the conclusions for the alloys corrosion performance in acidic and basic solutions are provided.

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.