Amine-Functionalized Meso-Macroporous Polymers for Efficient CO2 Capture from Ambient Air

Over the past decade, direct air capture (DAC) of carbon dioxide (CO2) using solid nanoadsorbents has garnered attention as a negative emission technology with high energy efficiency. Although operational, the large-scale deployment of DAC technologies has been significantly delayed due to the low performance and high cost of solid DAC nanoadsorbents. Herein, we present a novel family of meso-macroporous melamine formaldehyde (MF) materials with a facile preparation methodology, low capital cost, and unique physicochemical characteristics for DAC. The fabricated MF materials exhibit an extra-large pore volume of 5.19 cm3/g with a 24.6 nm average pore diameter. We show that the synthesized MF materials can be used as substrates and impregnated with different amounts of tetraethylenepentamine (TEPA) to act as chemical nanoadsorbents for DAC. Owing to the ultrahigh pore volume of MF, a substantial amount of 71 wt % TEPA (i.e., MF-TEPA71%) can be loaded, resulting in 2.65 mmol/g of CO2 uptake under DAC conditions. In addition, the superior physicochemical properties of MF lead to a high CO2 loading of 2.07 mmol/g with low TEPA loading in MF-TEPA33%. The prepared MF-TEPA nanoadsorbents can be successfully employed in different shapes (i.e., droplets, pellets, and coatings) and maintain their superiority across different temperatures and CO2 concentrations. This study provides a promising approach for developing meso-macroporous substrates through a straightforward and scalable synthesis method, representing a new avenue for the next generation of DAC nanoadsorbents with superior performance for practical applications.

Enhanced pollutant photodegradation over nanoporous titanium-vanadium oxides with improved interfacial interactions

This study addressed the separation problem of colloidal catalytic powder from its solution and pore blockage of traditional metallic oxides by fabricating nanoporous composites of titanium (Ti)-vanadium (V) oxide via magnetron sputtering, electrochemical anodization, and annealing processes. The effect of V-deposited loading on the composite semiconductors was investigated by varying V sputtering power (20-250 W) to correlate their physicochemical properties to the photodegradation performance of methylene blue. The obtained semiconductors revealed circular and elliptical pores (14-23 nm) and formed different metallic and metallic oxide crystalline phases. Within the nanoporous composite layer, V ions substituted Ti⁴⁺, leading to Ti³⁺ formation accompanied by decreased band gap values and higher visible-light absorption. Thus, the band gap of TiO₂ was 3.15 eV, while that of Ti-V oxide with the maximum V content (at 250 W) was 2.47 eV. The interfacial separators between clusters in the mentioned composite created traps disrupting the charge carrier movements between crystallites, thereby decreasing the photoactivity. In contrast, the composite prepared with the minimum V content showed approximately 90% degradation efficiency under solar-simulated irradiation resulting from the homogeneous V dispersion and the lower recombination possibility, owing to its p-n heterojunction constituent. The nanoporous photocatalyst layers with their novel synthesis approach and outstanding performance can be applied in other environmental remediation applications.

Upgrading the biogas production from raw landfill leachate using O3/H2O2 pretreatment process: Modeling, optimization and anaerobic digestion performance

Here, a combined pretreatment oxidation process (O₃/H₂O₂) was investigated to enhance the biodegradability of raw landfill leachate (RLL) and biomethane potential (BMP) in anaerobic reactors. The central composite design (CCD) and response surface methodology (RSM) were employed to optimize the operational parameters influencing on RLL bioavailability in O₃/H₂O₂ process: pH, Oxygen Flow rate, Reaction Time, and H₂O₂ concentration. The findings revealed that the O₃/H₂O₂ increased biodegradability index (BOD₅/COD) of RLL from 0.41 to 0.68 under optimized condition (pH=8, Oxygen flow= 0.25 L.min^-1, Reaction Time= 25 min, H₂O₂ concentration= 2.5 g.L^-1). Furthermore, the effects of O₃/H₂O₂ process on BMP of RLL were surveyed under mesophilic anaerobic reactors (Temperature: 37 ± 1 °C) in viewpoints of operational performance and methane yield in a batch mode for incubation period of 24 days. The results showed that O₃/H₂O₂ process simultaneously improve the BMP by 2.99 times higher in a shorter lag-phase period (5 days) compared with control. The pretreatment O₃/H₂O₂ and mesophilic anaerobic digestion process revealed a feasible and efficient method for enhance BMP of RLL.

The PCR-based detection and identification of the parasites causing human cutaneous leishmaniasis in the Iranian city of Ahvaz

In Iran, Leishmania major or L. tropica cause almost all of the human cutaneous leishmaniasis (CL). Unfortunately, the detection methods frequently used for CL (the microscopical examination of direct smears or the culture of biopsies) are not very sensitive and the Leishmania species causing each case of CL in Iran is usually only tentatively identified from extrinsic factors, such as the case's clinical manifestations and region of residence. Recently, however, a nested PCR that targets the parasites' kinetoplast DNA has been used in the city of Ahvaz (the capital of the province of Khouzestan, in south-western Iran) to confirm the microscopical diagnosis of CL and to identify the causative parasites, to species level. Smears from the lesions on 100 suspected cases of CL were fixed, stained with Wright's eosin-methylene blue, and checked for amastigotes under a light microscope. Scrapings from the same smears were then tested for leishmanial DNA, using a nested PCR that allows the DNA from L. tropica to be identified and distinguished from that of L. major. The 100 smears investigated were all found amastigote-positive by microscopy and PCR-positive for either L. major DNA (97 smears) or L. tropica DNA (three smears). The predominant species causing CL in Ahvaz is therefore L. major.