Fe-N-Graphene Wrapped Al2O3/Pentlandite from Microalgae: High Fenton Catalytic Efficiency from Enhanced Fe3+ Reduction.

Efficient cycling of Fe3+/Fe2+ is a key step for the Fenton reaction. In this exploration, from microalgae, we have prepared a novel Fe-N-graphene wrapped Al2O3/pentlandite composite which showed high Fenton catalytic ability through accelerating of Fe3+ reduction. The catalyst exhibits high activity, good reusability along with stability, and wide adaptation for the organics degradation under neutral pH. High TON and H2O2 utilization efficiency have also reached by this catalyst. Characterization results disclose a unique structure that the layered Fe-N-graphene structure tightly covers on Al2O3/pentlandite particles. Mechanistic evidence suggests that the accelerated Fe3+/Fe2+ redox cycle originates from the enhanced electron transfer by the synergistic effect of Fe, Ni and Al in the catalyst, and it causes the low H2O2 consumption and high •OH generation rate. Moreover, organic radicals formed in the Fenton process also participate in the Fe3+ reduction, and this process may be accelerated by the N doped graphene through a quick electron transfer. These findings stimulate an approach with great potential to further extend the synthetic power and versatility of Fenton catalysis through N doped graphene in catalysts.

Comparing the influence of humic/fulvic acid and tannic acid on Cr(VI) adsorption onto polystyrene microplastics: Evidence for the formation of Cr(OH)3 colloids.

Microplastics (MPs) can act as vectors for various contaminants in the aquatic environment. Although some research has investigated the adsorption characteristics and influencing factors of metals/organic molecules on MPs, the effects of dissolved organic matter (DOM) (which are ubiquitous active species in ecosystems) on metal oxyanions such as Cr(VI) capture by MPs are largely unknown. This study explored the adsorption behaviors and mechanisms of Cr(VI) oxyanions onto polystyrene (PS) MPs using batch adsorption experiments and multiple spectroscopic methods. The effects of representative DOM components (i.e., humic acid (HA), fulvic acid (FA) and tannic acid (TA)) on Cr(VI) capture by PS were particularly studied. Results revealed a significantly enhanced adsorption of Cr(VI) on PS in the presence of TA. The Cr(VI) adsorption capacity was increased from 2876 µg g-1 to 4259 µg g-1 and 5135 µg g-1 when the TA concentrations raised from 0 to 10 and 20 mg L-1, respectively. Combined microscopic and spectroscopic investigations revealed that Cr(VI) was reduced to Cr(III) by TA and formed stable Cr(OH)3 colloids on PS surfaces. Contrarily, HA and FA inhibited Cr(VI) adsorption onto PS, especially at pH > 2.0 and higher DOM concentrations, due to site competition and electrostatic repulsion. Increase in pH was found to reduce zeta potentials of MPs, resulting in inhibited Cr(VI) adsorption. The adsorbed Cr(VI) declined with increasing ionic strength, implying that outer-sphere surface complexation affected the adsorption process in the presence of DOM. These new findings improved our fundamental understanding of the fate of Cr(VI) and MPs in DOM-rich environmental matrices.

Performance and microbial communities of different biofilm membrane bioreactors with pre-anoxic tanks treating mariculture wastewater.

The performance of pollutant removals, activated sludge characteristics, and microbial communities of two biofilm membrane bioreactors coupled with pre-anoxic tanks (BF-AO-MBRs) (one using fiber bundle bio-carriers (FB-MBR) and the other using suspended bio-carriers (MB-MBR)) were compared at the salinity between zero and 60 g/L. At all salinities, three bioreactors showed good COD average removal efficiencies (>94.1%), and FB-MBR showed the best TN removal efficiency (90.4% at 30 g/L salinity). Moreover, FB-MBR had the faster process start-up time and better salt shock resistance. At high salinities (30-60 g/L), more extracellular polymeric substances were produced by the BF-AO-MBRs to avoid the penetration of salt and protect the bacterial community. Because of the different attachment patterns of biofilms, the microbial community structure in the FB-MBR exposed to 30 g/L salinity had higher nitrite-oxidizing/ammonia-oxidizing bacteria ratio (6.44) with more abundance of denitrifiers, which contribute to higher TN removal efficiency and lower nitrite accumulation.

Minimally invasive injectable lumbar interbody fusion with mineralized collagen-modified PMMA bone cement: A new animal model.

This study was to develop a feasible and safe animal model for minimally invasive injectable lumbar interbody fusion using a novel biomaterial, mineralized collagen-polymethylmethacrylate bone cement (MC-PMMA), with unilateral pedicle screw fixation in an in vivo goat model. Eight goats (Capra aegagrus hircus) were divided into three groups: MC-PMMA, unmodified commercial-polymethylmethacrylate bone cement (UC-PMMA), and a control group (titanium cage filled with autogenous bone, TC-AB). Each group of goats was treated with minimally invasive lumbar interbody fusion at the L3/L4 and L5/L6 disc spaces (injected for MC-PMMA and UC-PMMA, implanted for TC-AB). The pedicle screws were inserted at the L3, L4, L5, and L6 vertebrae, respectively, and fixed on the left side. The characteristics of osteogenesis and bone growth were assessed at the third and the sixth month, respectively. The methods of evaluation included the survival of each animal, X-ray imaging, and 256-layer spiral computed tomography (256-CT) scanning, imaged with three-dimensional microfocus computed tomography (micro-CT), and histological analysis. The results showed that PMMA bone cement can be extruded smoothly after doping MC, the MC-PMMA integrates better with bone than the UC-PMMA, and all goats recovered after surgery without nerve damage. After 3 and 6 months, the implants were stable. New trabecular bone was observed in the TC-AB group. In the UC-PMMA group a thick fibrous capsule had formed around the implants. The MC-PMMA was observed to have perfect osteogenesis and bone ingrowth to adjacent bone surface. Minimally invasive injectable lumbar interbody fusion using MC-PMMA bone cement was shown to have profound clinical value, and the MC-PMMA showed potential application prospects.