Enhanced vermicomposting of rice straw and pressmud with biogas slurry employing Eisenia fetida: Production, characterization, growth, and toxicological risk assessment.

The biogas plant plays a dual role: it directly provides energy and indirectly promotes organic farming through outlet slurry. However, agricultural biomass wastes such as rice straws (RS) and pressmud (PM), which can't be used as fertilizers on their own, were vermicomposted (60 days) with biogas slurry (BS), using earthworm, into four blends: T1(BS, 100%), T2(3:2, BS: RS), T3(3:2, BS: PM), and T4(3:1:1, BS: RS: PM). The characterization, elemental analysis, and toxicological risk assessment of derived vermimanure were carried out using various analytical tools, such as an organic elemental analyzer such as CHNS, FT-IR, FESEM-EDXA, XPS, and ICP-OES. The pH, electrical conductivity, and C/N values were within 7.1-7.8, 3.2-6.0 dSm-1, and 12-15, respectively, for all treatments. The proportions of N (38%), P (70%), K (58%), Mg (67%), Ca (42%), and ash (44%), increased significantly (P < 0.05) over the initial feedstocks. The ecological risks of heavy metals (Zn, Cu, Ni, Pb, Cd, and Cr) in all feedstocks were found to be under WHO-permitted levels. The growth performance of earthworms was also considerably higher (P < 0.05) over the control feedstock group. The analytical methods verified that feedstock T4 (3:1:1, BS: RS: PM) was more porous, containing NH4+, PO43-, K+, and other nutrients. Pellets of all vermimanure groups keep 65-75% of the original volume. As well, when these pellets have been employed for agronomy and dispersed in the field, they will cause less dust than traditional or powdered compost or manure. In comparison to the control group, the synergistic approach of RS, PM, and BS in vermimanure significantly (P < 0.05) enhanced seed germination (83%), vigour index (42.5%), and decreased mean germination time by 27%. Furthermore, pot trials with Abelmoschus esculentus seed indicated that seedlings cultivated with 40% vermimanure of T4 (3:1:1, BS: RS: PM) mixed soil showed high growth in shoot, root, and plant yield.

Copper-iron-molybdenum mixed oxides as efficient oxygen evolution electrocatalysts.

Ternary Cu, Fe and Mo mixed oxides having a nominal compositional formula, CuxFe2-x(MoO4)3 (0 ≤ x ≤ 1.5), have been prepared by a co-precipitation method at pH ≈ 2 and characterized by FT-IR, XRD, XPS, TEM and anodic polarization techniques for use as electrocatalysts for the oxygen evolution reaction (OER) in alkaline solutions. The crystallites of oxides with x ≤ 1 have the monoclinic crystal structure. The OER study shows that replacement of Fe in the Fe2(MoO4)3 matrix by 0.25-1.0 mol Cu increases the apparent electrocatalytic activity. However, 1.5 mol Cu-addition is detrimental to the OER activity. At E = 1.51 V (vs. RHE) in 1 M KOH, the catalytic activity of the oxide with x = 1 was approximately 50 times the activity of the base oxide (i.e. Fe2(MoO4)3). The Tafel slope of oxides with 0.25 ≤ x ≤ 1.5 ranged between 31 and 37 mV. The reaction order of OH(-) concentration was nearly unity for oxides with x = 0.25 and 1.5 and it was ∼2 for oxides with x = 0.5, 0.75, and 1.0. Suitable reaction mechanisms consistent with the electrode kinetic parameters have also been proposed.

Graphene-cobaltite-Pd hybrid materials for use as efficient bifunctional electrocatalysts in alkaline direct methanol fuel cells.

Hybrid materials comprising of Pd, MCo2O4 (where M = Mn, Co or Ni) and graphene have been prepared for use as efficient bifunctional electrocatalysts in alkaline direct methanol fuel cells. Structural and electrochemical characterizations were carried out using X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, chronoamperometry and cyclic, CO stripping, and linear sweep voltammetries. The study revealed that all the three hybrid materials are active for both methanol oxidation (MOR) and oxygen reduction (ORR) reactions in 1 M KOH. However, the Pd-MnCo2O4/GNS hybrid electrode exhibited the greatest MOR and ORR activities. This active hybrid electrode has also outstanding stability under both MOR and ORR conditions, while Pt- and other Pd-based catalysts undergo degradation under similar experimental conditions. The Pd-MnCo2O4/GNS hybrid catalyst exhibited superior ORR activity and stability compared to even Pt in alkaline solutions.