Solubilization of struvite and biorecovery of cerium by Aspergillus niger

Cerium has many modern applications such as in renewable energies and the biosynthesis of nanomaterials. In this research, natural struvite was solubilized by Aspergillus niger and the biomass-free struvite leachate was investigated for its ability to recover cerium. It was shown that struvite was completed solubilized following 2 weeks of fungal growth, which released inorganic phosphate (Pi) from the mineral by the production of oxalic acid. Scanning electron microscopy (SEM) showed that crystals with distinctive morphologies were formed in the natural struvite leachate after mixing with Ce3+. Energy-dispersive X-ray analysis (EDXA), X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR) confirmed the formation of cerium phosphate hydrate [Ce(PO4)·H2O] at lower Ce concentrations and a mixture of phosphate and cerium oxalate decahydrate [Ce2(C2O4)3·10H2O] at higher Ce concentrations. The formation of these biogenic Ce minerals leads to the removal of > 99% Ce from solution. Thermal decomposition experiments showed that the biogenic Ce phosphates could be transformed into a mixture of CePO4 and CeO2 (cerianite) after heat treatment at 1000 °C. These results provide a new perspective of the fungal biotransformation of soluble REE species using struvite leachate, and also indicate the potential of using the recovered REE as biomaterial precursors with possible applications in the biosynthesis of novel nanomaterials, elemental recycling and biorecovery. Key points • Cerium was recovered using a struvite leachate produced by A. niger. • Oxalic acid played a major role in struvite solubilization and Ce phosphate biorecovery. • Resulting nanoscale mineral products could serve as a precursor for Ce oxide synthesis.

PMMA – C60 composite: thermal decomposition experiments in mass spectrometer and quantum chemical modeling

Mass-spectrometric thermal decomposition experiments with submicron films of neat polymethylmethacrylate (PMMA), and PMMA-fullerene composite (PMMA-C60) after UV irradiation are discussed. The experiment registers thermal desorption mass spectra (TDMS), that is the monomer desorption rate versus time upon gradual heating the PMMA films in a given heating regime. The spectra provide information on the amount of the monomer desorbed at different decomposition stages upon heating the given amount of film material as well as on the spectral shape changes. It is shown that both amount of monomer and the TDMS spectral shape are sensitive to the presence of fullerene and UV irradiation. The experimental results are discussed in terms of quantum chemical models of binding. The DFT/B3LYP-D3/def2/J RIJCOSX level of theory was used. The MMA-C60 structures which can yield different amounts of monomer have been compared.

Application of Floating TiO2 Photocatalyst for Methylene Blue Decomposition and Salmonella Typhimurium Inactivation

The growing level of wastewater as well as pollution of freshwater by various bacteria are essential worldwide issues which have to be solved. In this contribution, nanocrystalline anatase TiO2 films deposited by magnetron sputtering on high-density polystyrene (HDPE) beads were applied as floating photocatalysts for Salmonella Typhimurium bacterial inactivation in water for the first time. Additionally, the photocatalytic degradation of methylene blue dye in the presence of HDPE beads with TiO2 film under UV-B irradiation was investigated. The suitability to adopt such floating photocatalyst structures for practical applications was tested in cycling experiments. The detailed surface morphology, crystal structure, elemental mapping, surface chemical composition and bond analysis of deposited TiO2 films were investigated by scanning electron microscope, X-ray diffractometer and X-ray photoelectron spectroscope techniques. The bacterial viability as well as MB decomposition experiments showed promising results by demonstrating that 6% of bacterial colonies were formed after the first run and only about 1% after the next four runs, which is an appropriate outcome for practical applications. NPN uptake results showed that the permeability of the outer membrane was significantly increased as well.

A Numerical Model of Biomass Combustion Physical and Chemical Processes

Identifying a modeling procedure of biomass thermal decomposition that is not only simple enough to implement and use, and computationally efficient, but also sufficiently accurate for engineering design activities, and with a spectrum of applications as broad as possible is a very difficult task. The authors propose a procedure which consists of two main stages: (a) the static modeling phase with the purpose of generating the algorithm (macro functions) that supplies a Computational Fluid Dynamics (CFD) model with specific input data (source/sink terms and local material properties) and (b) the dynamic modeling phase, where the CFD model is bi-directionally coupled to the external biomass decomposition model in the form of a User-Defined Function (UDF). The modeling approach was successfully validated against data obtained from single particle decomposition experiments, demonstrating its applicability even to large biomass particles, under high heating rates and combusting conditions.

Experimental and Density Functional Theory Studies on 1,1,1,4,4,4-Hexafluoro-2-Butene Pyrolysis

A series of thermal decomposition experiments were conducted over a temperature range of 873–1073 K to evaluate the thermal stability of 1,1,1,4,4,4-hexafluoro-2-butene (HFO-1336mzz(Z)) and the production of hydrogen fluoride (HF). According to the detected products and experimental phenomena, the thermal decomposition of HFO-1336mzz(Z) could be divided into three stages. Our experimental results showed that HF concentration gradually increased with the elevation of thermal decomposition temperature. In this present study, a total of seven chemical reaction pathways of HFO-1336mzz(Z) pyrolysis were proposed to explore the generated mechanism on products through density functional theory (DFT) with M06-2X/6-311++(d,p) level theory. The thermal decomposition mechanism of pure HFO-1336mzz(Z) was discussed and the possible formation pathways of HF and other main products were proposed.

Fabrication and Characterization of a Novel Composite Magnetic Photocatalyst β-Bi2O3/BiVO4/MnxZn1−xFe2O4 for Rhodamine B Degradation under Visible Light

β-Bi2O3/BiVO4/MnxZn1−xFe2O4 (BV/MZF) composite magnetic photocatalyst was first synthesized using the hydrothermal and calcination method. BV/MZF was a mesoporous material with most probable pore size and specific surface area of 18 nm and 17.84 m2/g, respectively. Due to its high saturation magnetization (2.67 emu/g), the BV/MZF composite can be easily separated and recovered from solution under an external magnetic field. The results of photo-decomposition experiments show that the decomposition rate of Rhodamine B (RhB) by BV/MZF can reach 92.6% in 3 h under visible light. After three cycles, BV/MZF can still maintain structural stability and excellent pollutant degradation effect. In addition, analysis of the photocatalytic mechanism of BV/MZF for RhB shows that the p-n heterojunction formed in BV/MZF plays a vital role in its photocatalytic performance. This work has potential application in the future for solving environmental pollution.

Do Foliar Endophytes Matter in Litter Decomposition?

Litter decomposition rates are affected by a variety of abiotic and biotic factors, including the presence of fungal endophytes in host plant tissues. This review broadly analyzes the findings of 67 studies on the roles of foliar endophytes in litter decomposition, and their effects on decomposition rates. Aquatic (i.e., in-stream) decomposition studies of endophyte-affected litter were significantly under-represented in the search results (P < 0.0001). Indicator species analyses revealed that different groups of fungal endophytes were significantly associated with cool or tropical climates, as well as specific plant host genera (P < 0.05). Finally, we argue that host plant and endophyte interactions can significantly influence litter decomposition rates and should be considered when interpreting results from both terrestrial and in-stream litter decomposition experiments.