Scott W. Donne

Shifting paradigms: development of high-efficiency biochar fertilizers based on nano-structures and soluble components

Many biochars have a complex carbon lattice structure with aromatic and aliphatic domains, acidic and basic groups, vacancies, metallic and non-metallic elements, and free radicals. Biochars also have separate mineral oxide, silicate and salt phases, and small and large organic molecules. In the rhizosphere, such constituents can be involved in chemical and biological processes along a soil–microbe–plant continuum, including nutrient cycling, metal chelation and stabilization, redox reactions, and free radical scavenging. It is hypothesized that the greater the amount of these nanoparticles and dissolved components, the greater will be plant and microbial responses. We provide suggestions for developing low-dose, high-efficiency biochar–nanoparticle composites, as well as initial field trial results and detailed characterization of such a biochar–fertilizer composite, to highlight the potential of such biochars.

Redox Processes at the Manganese Dioxide Electrode II. Slow‐Scan Cyclic Voltammetry

Slow-scan cyclic voltammetry was used to investigate the voltammetric behavior of electrolytic manganese dioxide (EMD), birnessite, chemically modified EMD (Bi-CMEMD), and birnessite (Bi-birnessite)electrodes under a variety of experimental conditions. During reduction, each electrode underwent a homogeneous reduction stage followed by a heterogeneous reduction stage. The composition at which the transition between these two stages occurred was dependent on the material under study. The initial cycle of the Bi-CMEMD electrode was similar to that of the EMD electrode. However, during the second cycle its behavior was similar to that of the Bi-birnessite electrode. This change in mechanism imparts rec argeable behavior to the Bi-CMEMD electrode. The end product of also dependent Mn(OH) 2 , except for the birnessite electrode, where Mn 3 O 4 was formed. The behavior of each electrode was also dependent on the graphite content used in the electrode, the electrolyte concentration, and the particle size of the manganese dioxide under study. The homogeneous reduction stage, which is a reaction involving a solid solution, favors a high proportion of graphite in the electrode and fine manganese dioxide particles. The heterogeneous reduction stage, which involves the formation of a soluble intermediate, was enhanced with concentrated KOH electrolytes and fine manganese dioxide particles. The influence of EMD surface area on electrode behavior was also investigated. The oxidation of Mn(OH) 2 in each electrode proceeded through a variety of solid Mn3 + intermediates to form a birnessite-like phase of manganese dioxide. The Bi 3+ ions in the chemically modified electrodes were incorporated into the structure of the oxidation product.

Redox Processes at the Manganese Dioxide Electrode I. Constant‐Current Intermittent Discharge

The reduction of electrodeposited manganese dioxide (EMD), birnessite, and Bi-birnessite electrodes was investigated using a constant-current intermittent discharge technique under conditions where major kinetic effects had been minimized. The results suggested that each type of manganese dioxide underwent a homogeneous reduction followed by a heterogeneous reduction stage. The transition between these reaction mechanisms occurred at a composition that was dependent on the manganese dioxide used. The homogeneous reduction of each electrode was a complex process involving the reduction of Mn 4+ ions within the various manganese dioxide structures. The heterogeneous reduction of the electrodeposited manganese dioxide and Bi-birnessite electrodes resulted in formation of Mn(OH) 2 , whereas heterogeneous reduction of the birnessite electrode resulted in formation of Mn 3 O 4

Redox Processes at the Manganese Dioxide Electrode III. Detection of Soluble and Solid Intermediates during Reduction

The soluble and solid-state intermediates formed during redox cycling of electrodeposited manganese dioxide (EMD), birnessite and chemically modified EMD (Bi-CMEMD), and birnessite (Bi-birnessite) electrodes were investigated using a stationary detector electrode (soluble intermediates) and x-ray diffraction (solid-state intermediates). Reduction of each electrode type can be divided into a homogeneous stage followed by a heterogeneous stage. For all electrode types, homogeneous reduction was a solid-state process involving proton and electron insertion into the manganese dioxide structure, causing a lattice expansion. Toward the end of homogeneous EMD reduction, soluble species were detected, presumably due to an equilibrium shift between solid and solution phase Mn 3+ species. The homogeneous/heterogeneous transition was also electrode dependent; i.e., ∼MnO 1.55 for EMD and Bi-CMEMD, ∼MnO 1.33 for birnessite, and ∼MnO 1.33 for Bi-birnessite. Heterogeneous electrochemical behavior was also electrode dependent. Initial heterogeneous reduction of EMD, Bi-birnessite, and Bi-CMEMD proceeded through a soluble Mn 3+ intermediate to form Mn(OH) 2 . Electrolyte concentration effects were more pronounced in this stage, since more concentrated KOH electrolytes lead to greater Mn 3+ solubility. The composition at which Mn(OH) 2 was first detected in the Bi-birnessite electrode suggested that the Mn(IV) to Mn(III) and Mn(III) to Mn(II) reduction processes occurred simultaneously. Heterogeneous reduction of birnessite was a solid-state process that resulted in Mn 3 O 4 , which is electrochemically inactive. Mn(OH) 2 oxidation resulted in formation of birnessite, the exact nature of which depended on the presence or absence of Bi 3+ ions. Under these deep discharge cycling conditions, the EMD electrode behaved poorly due to the eventual formation of Mn 3 O 4 . However, the Bi-birnessite and Bi-CMEMD electrodes are rechargeable due to the presence of Bi 3+ ions, which prevent Mn 3 O 4 formation

Microwave induced MIP synthesis: comparative analysis of thermal and microwave induced polymerisation of caffeine imprinted polymers

Caffeine templated molecularly imprinted polymers (MIPs) have been prepared using identical polymer formulations by thermal and microwave induced initiation, and the binding performance of the systems compared using solid phase extraction (SPE). While the binding capacity of MIP(Microwave) was found to be lower than MIP(Thermal), MIP(Microwave) recorded a higher imprinting factor (IF) due to comparatively low levels of non-specific binding. Selectivity against theophylline in cross-reactivity studies was also found to be greater for MIP(Microwave). While large time savings are achievable through the use of microwave irradiation conditions, physical analysis of the polymers (surface area analysis, thermal gravimetric analysis and differential scanning calorimetry) reveals that the different polymerisation methods lead to differences in both polymer structure and performance.

Mineral-Biochar Composites: Molecular Structure and Porosity.

Dramatic changes in molecular structure, degradation pathway, and porosity of biochar are observed at pyrolysis temperatures ranging from 250 to 550 °C when bamboo biomass is pretreated by iron-sulfate-clay slurries (iron-clay biochar), as compared to untreated bamboo biochar. Electron microscopy analysis of the biochar reveals the infusion of mineral species into the pores of the biochar and the formation of mineral nanostructures. Quantitative (13)C nuclear magnetic resonance (NMR) spectroscopy shows that the presence of the iron clay prevents degradation of the cellulosic fraction at pyrolysis temperatures of 250 °C, whereas at higher temperatures (350-550 °C), the clay promotes biomass degradation, resulting in an increase in both the concentrations of condensed aromatic, acidic, and phenolic carbon species. The porosity of the biochar, as measured by NMR cryoporosimetry, is altered by the iron-clay pretreatment. In the presence of the clay, at lower pyrolysis temperatures, the biochar develops a higher pore volume, while at higher temperature, the presence of clay causes a reduction in the biochar pore volume. The most dramatic reduction in pore volume is observed in the kaolinite-infiltrated biochar at 550 °C, which is attributed to the blocking of the mesopores (2-50 nm pore) by the nonporous metakaolinite formed from kaolinite.

Lowering N2O emissions from soils using eucalypt biochar: the importance of redox reactions

Agricultural soils are the primary anthropogenic source of atmospheric nitrous oxide (N2O), contributing to global warming and depletion of stratospheric ozone. Biochar addition has shown potential to lower soil N2O emission, with the mechanisms remaining unclear. We incubated eucalypt biochar (550 °C) – 0, 1 and 5% (w/w) in Ferralsol at 3 water regimes (12, 39 and 54% WFPS) – in a soil column, following gamma irradiation. After N2O was injected at the base of the soil column, in the 0% biochar control 100% of expected injected N2O was released into headspace, declining to 67% in the 5% amendment. In a 100% biochar column at 6% WFPS, only 16% of the expected N2O was observed. X-ray photoelectron spectroscopy identified changes in surface functional groups suggesting interactions between N2O and the biochar surfaces. We have shown increases in -O-C = N /pyridine pyrrole/NH3, suggesting reactions between N2O and the carbon (C) matrix upon exposure to N2O. With increasing rates of biochar application, higher pH adjusted redox potentials were observed at the lower water contents. Evidence suggests that biochar has taken part in redox reactions reducing N2O to dinitrogen (N2), in addition to adsorption of N2O.

The spermostatic and microbicidal actions of quinones and maleimides: toward a dual-purpose contraceptive agent.

There is an urgent need to develop safe, effective, dual-purpose contraceptive agents that combine the prevention of pregnancy with protection against sexually transmitted diseases. Here we report the identification of a group of compounds that on contact with human spermatozoa induce a state of “spermostasis,” characterized by the extremely rapid inhibition of sperm movement without compromising cell viability. These spermostatic agents were more active and significantly less toxic than the reagent in current clinical use, nonoxynol 9, giving therapeutic indices (ratio of spermostatic to cytotoxic activity) that were orders of magnitude greater than this traditional spermicide. Although certain compounds could trigger reactive oxygen species generation by spermatozoa, this activity was not correlated with spermostasis. Rather, the latter was associated with alkylation of two major sperm tail proteins that were identified as A Kinase-Anchoring Proteins (AKAP3 and AKAP4) by mass spectrometry. As a consequence of disrupted AKAP function, the abilities of cAMP to drive protein kinase A-dependent activities in the sperm tail, such as the activation of SRC and the consequent stimulation of tyrosine phosphorylation, were suppressed. Furthermore, analysis of microbicidal activity using Chlamydia muridarum revealed powerful inhibitory effects at the same low micromolar doses that suppressed sperm movement. In this case, the microbicidal action was associated with alkylation of Major Outer Membrane Protein (MOMP), a major chlamydial membrane protein. Taken together, these results have identified for the first time a novel set of cellular targets and chemical principles capable of providing simultaneous defense against both fertility and the spread of sexually transmitted disease.

Effects of enriched biochars containing magnetic iron nanoparticles on mycorrhizal colonisation, plant growth, nutrient uptake and soil quality improvement

Abstract At present, there is little commercial sale of biochar, since farmers find they can not gain a return on their investment in this amendment in the first few years after its application, because of the high cost associated with large application rates. To overcome this constraint, development of artificially aged enriched biochar-mineral complexes (BMCs), having a higher mineral content, surface functionality, exchangeable cations, high concentration of magnetic iron (Fe) nanoparticles, and higher water-extractable organic compounds has been undertaken by a combined team of researchers and a commercial company. Two biochars produced under different pyrolysis conditions were activated with a phosphoric acid treatment. A mixture of clay, chicken litter, and minerals were added to the biochar, and then this composite was torrefied at either 180 or 220 °C. In this study a pot experiment was carried out in glasshouse conditions to determine the effects of four different BMCs, with different formulations applied at rates of 100 and 200 kg ha−1, on the mycorrhizal colonisation, wheat growth and nutrient uptake, and soil quality improvement. It was found that the phosphorus (P) and nitrogen uptake in wheat shoots were significantly greater for a low application rate of BMCs (100 kg ha−1). The present formulation of BMC was effective in enhancing growth of wheat at low application rate (100 kg ha−1). The increase in growth appeared due to an increase in P uptake in the plants that could be partly attributed to an increase in mycorrhizal colonisation and partly due to the properties of the BMC.

Feeding Biochar to Cows: An Innovative Solution for Improving Soil Fertility and Farm Productivity

Addition of biochar produced through thermal decomposition of biomass has been seen as a strategy to improve soils and to sequester carbon (C), but wide scale implementation of the technology requires to devise innovative profitable solutions. To develop biochar utilisation with an integrated system approach, an innovative program was implemented in 2012 on a 53-ha farm in Western Australia to determine the costs and benefits of integrating biochar with animal husbandry and improvement of pastures. Biochar was mixed with molasses and fed directly to cows. The dung-biochar mixture was incorporated into the soil profile by dung beetles. We studied the changes in soil properties over 3 years. Biochar extracted from fresh dung and from the soil to a depth of 40 cm was characterised. A preliminary financial analysis of the costs and benefits of this integrated approach was also undertaken. The preliminary investigation results suggested that this strategy was effective in improving soil properties and increasing returns to the farmer. It was also concluded that the biochar adsorbed nutrients from the cows gut and from the dung. Dung beetles could transport this nutrient-rich biochar into the soil profile. There was little evidence that the recalcitrant component of the biochar was reduced through reactions inside the gut or on/in the soil. Further research is required to quantify the long-term impact of integrating biochar and dung beetles into the rearing of cows.