Effects of modified biochars on the shifts of short-chain fatty acid profile, iron reduction, and bacterial community in paddy soil.

Biochar is well known as an effective means for soil amendment, and modification on biochar with different methods could improve the benefits for environmental remediation. In this study, two modified biochars were generated with nitric acid (NBC) and hydrogen peroxide (OBC) pretreatment, and a control biochar was produced after washing with deionized water (WBC). The dynamics of short-chain fatty acids (SCFAs), iron concentration and bacterial community in rice paddy soil amended with different biochars or without adding biochar (CK) were studied during 70 days of anaerobic incubation. Compared to CK treatment, the accumulation of SCFAs was largely inhibited by the amendment of biochars. Besides, OBC and WBC increased the accumulation of Fe(II) at the initial stage of incubation. Via 16S rRNA gene sequencing, modified biochars caused significant response of bacterial community in comparison to WBC at Day 0-1, and three biochars favored bacterial α-diversity in the paddy soil at the end of the incubation. Interestingly, positive and negative correlations between NBC and several bacteria taxa (e.g. Geobacter, Fonticella and Clostridium) were observed. The study revealed that modified biochars had significant effects on the shifts of SCFAs, Fe(III) reduction and bacterial diversity, which provides fundamental information for future application of modified biochars in rice cropping ecosystem.

[Enhanced Dewaterability of Waste-Activated Sludge in Presence of Fe(â ¡)-Activated Calcium Peroxide].

Ferrous iron-activated calcium peroxide (Fe2+/CaO2) was innovatively put forward to improve the dewaterability of waste-activated sludge. The effects of initial pH, Fe2+, and CaO2dosages on sludge dewatering performance were investigated and its internal mechanism for achieving deep sludge dewatering was thoroughly explored. The results indicated that the best dewatering performance was obtained by dosing 3.31 mmol·g-1 Fe2+ and 3.68 mmol·g-1 CaO2 under neutral pH, in which specific resistance to filtration (SRF) and water content (WC) reduced from 20.99×1012 m·kg-1 and 86.61% to 3.91×1012 m·kg-1 and 76.15%, respectively. Fe2+/CaO2 oxidation caused sludge microbial cell lysis, release of intracellular organic matter, and degradation of extracellular polymeric substances (EPS). Meanwhile, the generated Fe3+ facilitated re-flocculation of sludge particles into rigid and porous structure flocs, which was beneficial to the release of EPS-bound water to achieve deep sludge dewatering. From the perspective of technology and economy, the Fe2+/CaO2 process is economical and practical, and has a promising application prospect in improving the dewatering performance of waste-activated sludge.

A mixed ionic and electronic conducting dual-phase membrane with high oxygen permeability.

To combine good chemical stability and high oxygen permeability, a mixed ionic-electronic conducting (MIEC) 75 wt% Ce(0.85)Gd(0.1)Cu(0.05)O(2-δ)-25 wt% La(0.6)Ca(0.4)FeO(3-δ)(CGCO-LCF) dual-phase membrane based on a MIEC-MIEC composite has been developed. Copper doping into Ce(0.9)Gd(0.1)O(2-δ) (CGO) oxide enhances both ionic and electronic conductivity, which then leads to a change from ionic conduction to mixed conduction at elevated temperatures. For the first time we demonstrate that an intergranular film with 2-10 nm thickness containing Ce, Ca, Gd, La, and Fe has been formed between the CGCO grains in the CGCO-LCF one-pot dual-phase membrane. A high oxygen permeation flux of 0.70 mL min(-1) cm(-2) is obtained by the CGCO-LCF one-pot dual-phase membrane with 0.5 mm thickness at 950 °C using pure CO2 as the sweep gas, and the membrane shows excellent stability in the presence of CO2 even at lower temperatures (800 °C) during long-term operation.

High-flux oxygen-transporting membrane Pr(0.6)Sr(0.4)Co(0.5)Fe(0.5)O(3-δ): CO2 stability and microstructure.

High oxygen permeability and good thermochemical stability of oxygen-transporting membranes (OTMs) are two main requirements concerning the applicability of these devices in chemical processes, such as CO2 capture using the oxyfuel concept or catalytic membrane reactors. In this work, a single-phase perovskite-type membrane Pr0.6Sr0.4Co0.5Fe0.5O3-δ (PSCF) with 0.6-mm thickness was subjected to periodic thermal cycling in the temperature range between 850 and 1000 °C in a 1000-h long-term permeation test with pure CO2 as the sweep gas. The results of this long-term permeation operation revealed a stepwise increase in oxygen permeation values at 1000 °C after each thermal cycle, reaching from 1.38 cm(3) (STP) min(-1) cm(-2) in the first cycle to 1.75 cm(3) (STP) min(-1) cm(-2) in the fourth cycle. Furthermore, the membrane showed very good CO2 stability at 900 °C and above. Despite a partial decrease in oxygen permeation fluxes at 850 °C, a steady state of 0.25 cm(3) (STP) min(-1) cm(-2) was reached and maintained for more than 100 h. The newly developed PSCF membrane also exhibited a higher oxygen permeation flux with He and CO2 sweeping at all measured temperatures compared to a similar La0.6Sr0.4Co0.8Fe0.2O3-δ (LSCF) membrane.

A novel CO2-stable dual phase membrane with high oxygen permeability.

By cobalt-doping of the mixed conducting phase PSFC, a good combination of high CO2 stability and high oxygen permeability is obtained for the 60 wt% Ce(0.9)Pr(0.1)O(2-δ)-40 wt% Pr(0.6)Sr(0.4)Fe(0.5)Co(0.5)O(3-δ) (CP-PSFC) dual phase membrane, which suggests that CP-PSFC is a promising membrane for industrial applications in the oxyfuel process for CO2 capture.

Hydrogen production by water dissociation in surface-modified BaCo(x)Fe(y)Zr(1-x-y)O(3-delta) hollow-fiber membrane reactor with improved oxygen permeation.

A porous perovskite BaCo(x)Fe(y)Zr(0.9-x-y)Pd(0.1)O(3-delta) (BCFZ-Pd) coating was deposited onto the outer surface of a BaCo(x)Fe(y)Zr(1-x-y)O(3-delta) (BCFZ) perovskite hollow-fiber membrane. The surface morphology of the modified BCFZ fiber was characterized by scanning electron microscopy (SEM), indicating the formation of a BCFZ-Pd porous layer on the outer surface of a dense BCFZ hollow-fiber membrane. The oxygen permeation flux of the BCFZ membrane with a BCFZ-Pd porous layer increased 3.5 times more than that of the blank BCFZ membrane when feeding reactive CH(4) onto the permeation side of the membrane. The blank BCFZ membrane and surface-modified BCFZ membrane were used as reactors to shift the equilibrium of thermal water dissociation for hydrogen production because they allow the selective removal of the produced oxygen from the water dissociation system. It was found that the hydrogen production rate increased from 0.7 to 2.1 mL H(2) min(-1) cm(-2) at 950 degrees C after depositing a BCFZ-Pd porous layer onto the BCFZ membrane.

Neutral and cation-free LTA-type aluminophosphate (AlPO(4)) molecular sieve membrane with high hydrogen permselectivity.

A novel neutral and cation-free LTA-type AlPO(4) membrane has been prepared on porous asymmetric ceramic supports. Hydrogen can be effectively separated from other gases by molecular sieving.

Zeolitic imidazolate framework membrane with molecular sieving properties by microwave-assisted solvothermal synthesis.

A zeolitic imidazolate framework (ZIF-8) as member of the metal-organic framework family has been crystallized as a thin porous layer on an asymmetric ceramic support. Hydrogen can be selected from other gases by molecular sieving.

Direct decomposition of nitrous oxide to nitrogen by in situ oxygen removal with a perovskite membrane.

Direct decomposition of N(2)O to N(2) using perovskite hollow fiber membranes is achieved by combination with in situ oxygen removal (see picture). A coupled partial methane oxidation allows N(2)-free synthesis gas to be obtained. This sustainable process combines N(2)O removal with the simultaneous production of valuable chemicals.