Pore Blocking Effect Research Articles

Novel Binders for Aqueous Electrode Processing of Electrochemical Capacitors.

This work studies the use of epoxy and polyurethane formulations as binders for the aqueous processing of activated carbon (AC) electrodes used as positive and negative electrodes in Electrochemical Double Layer Capacitors (EDLCs). The use of amine and carbodiimide as crosslinkers is also evaluated. The mechanical properties of those different binders have been investigated, looking towards aqueous processable and flexible electrodes. Microstructural analysis of the fabricated AC electrodes has been carried out to understand the pore-blocking effect exhibited by certain polymers. Furthermore, electrochemical characterization of all the systems has been performed by cyclic voltammetry, electrochemical impedance spectroscopy, and constant current charge/discharge measurements at different current densities. The obtained results show that polyurethane outperforms in terms of energy and power density the CMC:SBR reference system. Moreover, the studied polyurethanes maintain close to 100% of their initial capacitance after 2500 cycles under a current density of 5 A g-1 and a discharge time of 20 s.

Developing geopolymer concrete using fine recycled concrete powder and recycled aggregates

To develop a sustainable geopolymer concrete (GC), the efficacy of using fine recycled concrete powder (FRCP) and recycled aggregates (RA) as partial replacements for fly ash (FA) and natural aggregates (NA), respectively, was investigated. The compressive strengths of different GCs were measured. The durability performance was assessed by means of capillary suction tests, initial surface absorption tests and acid attack performed at ambient curing. The compressive strength of the GC made with 50% RA (both coarse and fine) and FRCP was found to be comparable to that of GC made with NA. Similarly, the inclusion of FRCP in the GC mixes resulted in a pore-blocking effect, restricting water ingress to the GC through capillary suction and surface absorption, even with the use of 50% coarse RA and 25% fine RA. The results demonstrated that sustainable GC can be developed using appropriate doses of FRCP and RA.

Low-molecular-weight aromatic acids mediated the adsorption of Cd2+ onto biochars: effects and mechanisms.

Low-molecular-weight aromatic acids (LWMAAs), a ubiquitous organic substance in natural systems, are important in controlling the environmental fate of potentially toxic metals. However, little is known about the effects of LWMAAs on the interactions between biochars and potentially toxic metals. Herein, the influences of three aromatic acids, including benzoic acid (BA), p-hydroxy benzoic acid (PHBA), and syringic acid (SA), on the adsorption of Cd2+ onto biochars generated at three different pyrolysis temperatures under acidic and neutral conditions were examined. Generally, the adsorption ability of biochars for Cd2+ improved with the increase of pyrolysis temperature, which was ascribed to the increased inorganic element contents (e.g., P, S, and Si) and aromaticity, increasing the complexation between mineral anions and metal ions, and the enhanced cation-π interaction. Interestingly, aromatic acids considerably inhibited the adsorption of Cd2+ onto biochars, which was mainly ascribed to multi-mechanisms, including competition of LWMAA molecules and metal ions for adsorption sites, the pore blocking effect, the weakened interaction between mineral anions and Cd2+ induced by the adsorbed aromatic acids, and the formation of water-soluble metal-aromatic acid complexes. Furthermore, the inhibitory effects of LWMAAs on Cd2+ adsorption intensively depended on the aromatic acid type and followed the order of SA > PHBA > BA. This trend was related to the differences in the physicochemical features (e.g., the octanol/water partition coefficient (log Kow) and molecular size) of diverse LMWAAs. The results of this study demonstrate that the effects of coexisting LMWAAs should not be ignored when biochars are applied in soil remediation and wastewater treatment.

Gas permeation through carbon membranes: Model development and experimental validation

With a growing interest in carbon membranes for gas separation, understanding their performance and behaviour is essential for proper design of the membrane separation. Currently not many models exist that correctly describe transport through carbon membranes due to its complex nature. This work attempts to implement a general modelling approach which describes several key transport phenomena inside carbon membranes. The approach assumes a membrane wall to be a bundle of pores with parallel transport mechanisms using the pore size distribution as a weight factor to sum the different transport phenomena. This work adapts this approach specifically for carbon membranes, additionally accounting for molecular sieving and pore blocking effects. Imposing realistic boundary conditions, the model is solved using global optimization algorithms. For testing, four different CMSMs have been produced with hydroquinone and novolac precursors. Pure- and mixed gas permeation tests are done for these CMSMs with H2, N2, and CO2 and the model is fit to this permeation data. Fitting results with pure gas measurements show the model is able to predict the contributions of different mass transport mechanism for the different membranes. This is validated by comparing these results to gas-pair permselectivity data. The model is furthermore fit to mixed gas data. Existence of multi-component effects shows that the model could be further improved. Overall, the model presented in this work is shown to be able to describe complex mass transport behaviour for various different carbon membranes.

A facile synthesis approach for GO-ZnO/PES ultrafiltration mixed matrix photocatalytic membranes for dye removal in water: Leveraging the synergy between photocatalysis and membrane filtration

Photocatalytic membranes offer a unique opportunity of exploiting the combined benefits of membrane filtration and photocatalytic degradation, however, striking a practical balance between the two processes remains a challenging prospect. In this work, we explored the filtration and simulated solar light-mediated photocatalytic performance of polyethersulfone (PES) ultrafiltration membranes embedded with graphene oxide-zinc oxide (GO-ZnO) nanocomposite photocatalyst. A novel and simple double casting phase inversion method was used to fabricate the GO-ZnO/PES mixed matrix photocatalytic membranes with varying GO-ZnO loadings. Polyvinylpyrrolidone (PVP) was used as a pore-forming agent to minimize the pore blocking effect of high concentrations of GO-ZnO nanocomposite. The membranes were characterized for surface morphology and functionality, pore size, water uptake, and solute rejection properties using various techniques including scanning electron microscopy, atomic force microscopy, Raman spectroscopy, contact angle measurements, streaming potential analysis and cross-flow filtration. The incorporation of GO-ZnO improved the hydrophilicity of the membranes and the addition of PVP augmented the pure water flux of the PVP membranes compared to the PES membranes. Meanwhile, both PES and PVP membranes displayed poor overall salt rejection, which improved with increase in the GO-ZnO concentration. The rejection of carbamazepine and brilliant black (BB) followed a similar trend, with the highest rejection (carbamazepine ≈ 80%) and BB (≈ 70%) attained at 1% GO-ZnO. Furthermore, the PVP membrane with 1% GO-ZnO showed the highest photocatalytic degradation of BB, and the degradation kinetics were nearly 25 times higher than those recorded over the PVP membrane without nanoparticles. Overall, this work demonstrated that membrane filtration and photocatalytic properties can be improved by tailoring the membrane synthesis method to ensure high photocatalyst loading while retaining high flux, rejection, and photocatalytic capability.

Smart waste management perspective of COVID-19 healthy personal protective materials in concrete for decorative landscape pavements and artificial rocks

This paper presents a new method for determining the effect of healthy personal protective material (HPPM) stripes, such as surgical masks, protective suits, and overhead and foot covers, on the durability and physicomechanical characteristics of concrete for use in architectural forms. Because of the current global epidemic caused by coronavirus (COVID-19), the use of HPPM, such as surgical masks, protective suits, and overhead and foot covers, has increased considerably. COVID-19’s second and third waves are currently affecting various countries, necessitating the use of facemasks (FM). Consequently, millions of single FM have been discharged into the wild, washing up on beaches, floating beneath the seas, and ending up in hazardous locations. The effect of stripe fibers on the physicomechanical characteristics of concrete, such as the workability, Uniaxial Compressive Strength UCS, flexural strength, impact strength, spalling resistance, abrasion resistance, sorptivity, Water absorption Sw, porosity (ηe), water penetration, permeability, and economic and eco-friendly aspects, need to be determined. With a focus on HPPM, especially single-use facemasks, this study investigated an innovative way to incorporate pandemic waste into concrete structures. Scanning electron microscope and X-ray diffraction patterns were employed to analyze the microstructures and interfacial transition zones and to identify the elemental composition. The HPPM had a pore-blocking effect, which reduced the permeability and capillary porosity. Additionally, the best concentrations of HPPM, particularly of masks, were applied by volume at 0, 1, 1.5, 2.0, and 2.5%. The use of mixed fibers from different HPPMs increased the strength and overall performance of concrete samples. The tendency of growing strength began to disappear at approximately 2%. The results of this investigation showed that the stripe content had no effect on the compressive strength. However, the stripe is critical for determining the flexural strength of concrete. The UCS increased steadily between 1 and 1.5% before falling marginally at 2.5%, which indicates that incorporating HPPM into concrete had a significant impact on the UCS of the mixture. The addition of HPPM to the mixtures considerably modified the failure mode of concrete from brittle to ductile. Water absorption in hardened concrete is reduced when HPPM stripes and fibers were added separately in low-volume fractions to the concrete mixture. The concrete containing 2% HPPM fibers had the lowest water absorption and porosity percentage. The HPPM fibers were found to act as bridges across cracks, enhancing the transfer capability of the matrices. From a technological and environmental standpoint, this study found that using HPPM fibers in the production of concrete is viable.

Innovative flotation separation considering pores blocking to facilitate residual carbon recovery from coal gasification fine slag

The conventional flotation of coal gasification fine slag has the dilemma of large collector dosage and low carbon recovery due to the developed porosity of the residual carbon. In this study, an innovative method to enhance the flotation recovery of residual carbon was proposed by pores blocking with pulverized coal. Flotation experiments were carried out to verify the effect of pore blocking on the recovery of residual carbon, and scanning electron microscope, X-ray photoelectron spectroscopy, and mercury intrusion porosimetry were used for mechanism analysis. The results showed that the addition of pulverized coal did play a role in pores blocking in the novel flotation, and its carbon recovery rate was improved by 14.11% (absolute value) compared to that of conventional flotation at the same ash content of the concentrates. On the one hand, the pulverized coal adheres on the pore openings on the residual carbon surface, thus preventing the collector adsorption into the pore channels; on the other hand, the adhesion of pulverized coal to the residual carbon surface increases the adsorption sites for collector. Therefore, pores blocking is beneficial for more adsorption of the collector on the outer surface of the residual carbon and thus improving its flotation recovery. This paper provides significant inspiration for efficient flotation of coal gasification fine slag.

Enhanced Carbon Capture Behavior of Carbon Fibers via Ionic Liquid Modification

AbstractCarbon‐based materials are widely deployed in carbon capture but are only limited to physisorption procedures. Further extending functionalized carbon materials to CO2 chemisorption under low CO2 concentration is highly desirable yet challenging. Herein, a carbon fiber composed of solely ultra‐micropores (∼0.45 nm) was deployed as the precursor to avoid the pore blocking effect, which was modified by superbase‐derived ionic liquids (ILs) containing strong interaction sites with CO2. By forming a thin coating layer on the surface, the as‐afforded surface‐functionalized fiber materials demonstrated enhanced CO2 uptake capacity and improved CO2 sorption kinetics, as evaluated by both the volumetric method and thermogravimetric analysis, as well as the calculated energy distribution curves. The achievements made in this work provide guidance on the functionalization of carbon‐based materials towards enhanced CO2 chemisorption by forming a thin layer of selected IL coating.

Inhibition Effect of Hydrophobic Functional Organic Corrosion Inhibitor in Reinforced Concrete.

Using an admixed organic corrosion inhibitor is one of the most efficient strategies to enhance the corrosion resistance and durability of reinforced concrete. However, traditional admixed organic corrosion inhibitors only increase the corrosion resistance of the embedded reinforcing steel, and the optimization effect on the pore structure and the impermeability of concrete is very limited. In this study, in order to evaluate the corrosion-inhibition effect of a novel hydrophobic functional organic corrosion inhibitor, the adsorption behavior of a hydrophobic functional organic corrosion inhibitor and its related effect on the electrochemical behavior of the reinforcing steel was investigated. In addition, this paper further discusses the effect of a hydrophobic functional organic corrosion inhibitor on pore structure and hydrophobic properties, as well as the impermeability of concrete. The results indicated that the hydrophobic functional organic corrosion inhibitor was effectively adsorbed on the surface of the steel bar, and the higher adsorption content was relevant to the higher inhibitor dosage. On one hand, the hydrophobic functional organic corrosion inhibitor exhibited both a pore-blocking effect and a hydrophobic effect on concrete, leading to a refined pore structure and reduced capillary water absorption amount; on the other hand, the hydrophobic functional organic corrosion inhibitor exhibited an excellent corrosion-inhibition effect on the reinforcement embedded in the concrete, presenting an inhibition efficiency higher than 90% with a concentration of 4 wt.%.

Facile tailoring molecular sieving effect of PIM-1 by in-situ O3 treatment for high performance hydrogen separation

Highly efficient hydrogen separation membrane is critical in the future hydrogen powered zero carbon society. However, challenges left in searching for hydrogen separation membranes with high permeability, selectivity and easy accessibility. Here, this target was partially achieved by a series of membranes made from in-situ ozone oxidized intrinsic mciroporous polymer membranes (O3-PIMs) within minutes. The FT-IR spectra and XPS results suggested that CO and OH groups were formed after the oxidation reaction. The TGA and EDS mapping results indicated that the oxidation reaction happened only on the skin surface of PIM-1 membrane within 10 μm in depth. After O3 oxidation, the O3-PIMs showed a large drop in gas permeability whereas huge increases in gas pair selectivity, resulting in large improved overall performance for H2/N2, H2/CH4 and H2/CO2 that beat the latest trade-off lines. The O3-PIM-60 showed a H2 permeability of 1294 Barrer and H2/N2, H2/CH4 and H2/CO2 selectivity of 93.7, 121, and 2.92, respectively. The increased selectivity of O3-PIMs is due to their remarkably enhanced size sieving effect induced enhanced diffusion selectivity. Theoretical simulation showed that this is caused by the O3 reaction induced pore blocking effect that shifted the mciropore of PIM-1 to the ultra-micropore region, and thus, significantly improved the hydrogen sieving efficiency. In all, this facile and highly efficient ozone oxidation method provides a great perspective in searching for high performance hydrogen separation membranes.

In Situ Pumping–Injection Remediation of Strong Acid–High Salt Groundwater: Displacement–Neutralization Mechanism and Influence of Pore Blocking

Acid-polluted groundwater may cause many environmental problems due to its corrosivity. Pumping and injection technology is a commonly used remediation technology, and its main principles are displacement and neutralization. However, due to the high salinity in groundwater, blockage easily occurs and reduces the efficiency. The mechanism of pumping and remediation of strong acid–high salinity groundwater is unclear, and the mechanism and effect of pore blocking are unknown. In this paper, based on an actual polluted site, a field pumping test was carried out. Through groundwater monitoring and drilling core sampling, the process and mechanism of acid groundwater pumping–injection remediation were clarified, and the principle and impact of pore blockage are revealed. The results showed that increasing the injection pressure can effectively improve the repairing efficiency. When the pressure increased from 0.2 MPa to 0.3 MPa, the water injection efficiency per unit time was increased by more than 20%. The principle of pumping–injection remediation of acidic groundwater was mainly displacement, accounting for more than 93%, while neutralization only contributed less than 0.1%. Although the neutralization contribution was small, the neutralization interface of injected alkaline water and acidic groundwater was the main place for precipitation. The precipitation was mainly formed around the injection well, the amount of which decreases greatly with the increase in displacement distance. This was because the formation of precipitation required both an appropriate concentration of Fe and high pH (5.63). Affected by neutralization and dispersion, the pH of the acid–base water interface decreased and the necessary conditions for the formation of precipitation were not met. Therefore, in the actual pumping–injection restoration project, optimization can be carried out from two perspectives of appropriately increasing the injected water pressure and reducing the injected water pH. This study has important reference value for the control and remediation of such acid-polluted groundwater.

Lattice Model of Fluid Transport in Mixed Matrix Membranes

AbstractThis work offers a computationally efficient theoretical framework to investigate transport phenomena in complex systems such as mixed matrix membranes (MMMs). It is demonstrated here that a wide variety of heterogeneous, disordered geometries can be constructed using lattice models. These geometries combined with the dynamic mean field theory (DMFT) provide useful insights on the distribution of density and flux in the structures. From this work, the DMFT emerges as a theoretical playground to explore transport phenomena in MMMs under a variety of conditions and probe some of the assumptions involved in the commonly used macroscopic models. As a case study, a comparison of the predictions of the DMFT is considered with several classical macroscopic theories. In the preliminary observations, the study points to a much greater impact of the pore blocking effects on the overall transport of the composite system in comparison with the macroscopic models.

Interactions between H2O2 and dissolved organic matter during granular activated carbon-based residual H2O2 quenching from the upstream UV/H2O2 process

Granular activated carbon (GAC) filtration can be employed to synchronously quench residual H2O2 from the upstream UV/H2O2 process and further degrade dissolved organic matter (DOM). In this study, rapid small-scale column tests (RSSCTs) were performed to clarify the mechanisms underlying the interactions between H2O2 and DOM during the GAC-based H2O2 quenching process. It was observed that GAC can catalytically decompose H2O2, with a long-lasting high efficiency (>80% for approximately 50,000 empty-bed volumes). DOM inhibited GAC-based H2O2 quenching via a pore-blocking effect, especially at high concentrations (10 mg/L), with the adsorbed DOM molecules being oxidized by the continuously generated ·OH; this further deteriorated the H2O2 quenching efficiency. In batch experiments, H2O2 could enhance DOM adsorption by GAC; however, in RSSCTs, it deteriorated DOM removal. This observation could be attributed to the different ·OH exposure in these two systems. It was also observed that aging with H2O2 and DOM altered the morphology, specific surface area, pore volume, and the surface functional groups of GAC, owing to the oxidation effect of H2O2 and ·OH on the GAC surface as well as the effect of DOM. Additionally, the changes in the content of persistent free radicals in the GAC samples were insignificant following different aging processes. This work contributes to enhancing understanding regarding the UV/H2O2-GAC filtration scheme, and promoting the application in drinking water treatment.

Methane sorption behavior on tectonic coal under the influence of moisture

Water is widely distributed in coal under the in-situ reservoir conditions, which has a great impact on gas adsorption and migration within coal. In this work, methane sorption behavior on tectonic coal under the influence of moisture was quantitatively evaluated using the combination of high-pressure volumetric method, X-ray photoelectron spectrometer (XPS) and mercury intrusion porosimetry (MIP). Comparative analysis of the differences in microstructures and methane adsorption capacity was also made between primary coal and tectonic coal. The results show that a large number of micropores are contained in tectonic coal, leading to the increasing complexity of pore structure. Primary coal has less pores but the largest number of oxygen-containing functional groups. Methane sorption properties are affected by moisture content in varying degrees for primary coal and tectonic coal. Combined with XPS and MIP results, the influencing mechanism of water content on methane adsorption was revealed. CH4 adsorption in primary coal is more sensitive to water, and only 2% of moisture content leads to the 67% of reduction in the CH4 adsorption amount, which is attributed to the stronger hydrophilia and less pore space. Owing to the developed pore networks, the increase of water content only results in a slight reduction of adsorption capacity in mylonitic coal when moisture content less than 2.5%. The further increase of moisture content results in the pore-blocking effect, inhibiting the access of other gas adsorbing molecules to the pores, hence, methane adsorption capacity is greatly reduced in mylonitic coal. This work is of great significance for better understanding the adsorption/desorption processes of tectonic coal.

Fly-ash derived Na-P1, natural zeolite tuffs and diatomite in motor oil retention

Aluminosilicate materials of various grain sizes, i.e., Kimolos, Samos and Sorano zeolite tuffs, Samos diatomite and synthetic zeolite prepared from Meliti fly ash via alkaline hydrothermal treatment, were tested as new sorbents for oil leakage remediation. Two lubricant oils of different viscosity, i.e., SHELL HELIX HX5 20 W-50 and ULVAC SMR-100 were selected as potential adsorbates. All sorbents employed demonstrated exceptional oil retention capacity values exceeding 100% (w/w); specifically, Kimolos and Sorano zeolites as well as thermally treated Samos diatomite proved best reaching 160% (w/w) oil sorption. Mordenite and phillipsite were mostly detected in Kimolos and Italian zeolite tuffs, respectively. Na-P1 zeolite, produced for the first time from Meliti fly ash without pretreatment via a low-temperature hydrothermal procedure, was characterized by XRD and SEM. The zeolitization process, leading to Na-P1 as the sole synthesis product, was carried out without the use of additives. The synthetic Na-P1 zeolite displayed significant sorption capacity, retaining 125 and 105% (w/w) of the viscous and less viscous oils tested, respectively. Thus, valorization of all aluminosilicate materials employed was achieved. Both porosity measurements and SEM micrographs demonstrated that the highest lubricant oil retention values were reached by macroporous adsorbents having open structure and large surface area, suitable for overcoming the fluid’s resistance to flow and avoiding pore-blocking effects.

Fluorinated strategy of node structure of Zr-based MOF for construction of high-performance composite polymer electrolyte membranes

The dispersion and compatibility of metal–organic frameworks (MOFs) in polymeric matrices significantly influence the properties of composite membranes. However, the modification and functionalization of the node structures of MOFs to improve their dispersion in the polymeric matrix have been rarely studied. In this work, the node structures of UiO-66-NH2 frameworks were modified by the introduction of F species, and abundant Zr–F bonds and pore blocking effects were generated, which significantly affected the comprehensive performances of the composite membranes, including the dispersion, mechanical properties, proton conductivities, swelling ratios, and water uptake. Due to the good dispersion of the fluorinated MOF nanoparticles in the Nafion matrix, the composite membranes had high proton/methanol selectivity and low methanol permeability, which exhibited superior fuel cell performances in DMFCs (24.9–26.8 mW cm−2) to that of recast Nafion (20.4 mW cm−2). Notably, this was the first time that the node structures of MOF-based nanoparticles were fluorinated to improve their dispersion in a polymeric matrix, providing a simple strategy for developing high-performance composite membranes.

Capillary Imbibition in Cementitious Materials: Effect of Salts and Exposure Condition

Concrete structures are often exposed to harsh environmental conditions during their service life. Therefore, the investigation of transport properties and deterioration of concrete in different environments is an important topic. This paper reports the influence of salts (NaCl and Na2SO4) and exposure conditions (ideal laboratory (20 °C, 95% RH), a city and sea environment; including sheltered and exposed conditions) on capillary imbibition in cementitious materials with different water to cement ratios (0.4 and 0.6). First, the pore structure was assessed by water absorption under vacuum, torrent permeability, resistivity, and moisture content. The second part revolves around the capillary imbibition phenomenon with different imbibition liquids (water, NaCl, and Na2SO4). The results showed that, among the studied exposure conditions, sheltered conditions resulted in the largest porosity values and capillary imbibition rates (CIR). The influence of the imbibing liquid on the CIR depends on the w/c of the concrete. The CIR value for samples with a w/c of 0.4 is lower for Na2SO4 as imbibing liquid in comparison to water and NaCl. The sulfates might cause a pore blocking effect leading to a decreased CIR. For concrete with a w/c of 0.6, there was no significant difference between the different imbibition liquids. The influence of the pore blocking effect is probably smaller due to the larger porosity in this case. The findings of this research are important to understand the influence of real-life exposure conditions and therefore the influence of relative humidity, temperature, carbonation, and chloride ingress on the capillary imbibition phenomenon.

Carbon fibres as potential bone implants with controlled doxorubicin release

This work presents the structural characterisation of carbon fibres obtained from the carbonization of flax tow at 400°C (CFs400°C) and 1000°C (CFs1000°C) and the thermodynamic and kinetic studies of adsorption of Doxorubicin (Dox) on the fibres. The characteristic of carbon fibres and their drug adsorption and removal mechanism were investigated and compared with that of natural flax tow. All fibres were fully characterized by scanning electron microscopy (SEM), Fourier transforms infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), specific surface area analysis and Boehm titration. The results demonstrated the highest adsorption properties of CFs400°C at 323 K (qmax = 275 mg g−1). The kinetic data followed the pseudo-second-order kinetic model more closely, whereas the Dubinin–Radushkevich model suitably described isotherms for all fibres. Calculated parameters revealed that the adsorption process of Dox ions is spontaneous and mainly followed by physisorption and a pore-filling mechanism. The removal efficiency for carbon fibres is low due to the effect of pore-blocking and hydrophobic hydration. However, presented fibres can be treated with a base for further chemical surface modification, increasing the adsorption capacity and controlling the release tendency.

CO2 dual roles in food scraps-derived biochar activation to enhance lead adsorption capacity

Driven by China's waste classification system, the recycling of food scraps is a work of great importance. The carbonate (CO32−) and phosphate (PO43−) in food scraps indicate that its derived biochar can be a good candidate for Pb immobilization. In the current study, Pb2+ adsorption sites (CO32− and PO43−) of biochar were adjusted by carrier gas atmosphere and activation temperature. Results indicate that CO2 has dual roles in activation of food scraps-derived biochar. CO2 can not only inhibit the decomposition of CO32− but also increase the content of PO43− via consuming aromatic carbon combined with phosphorus at high temperature (>600 °C). Thus, the biochar prepared at 700 °C and CO2 atmosphere has more adsorption sites, resulting in an outstanding Pb adsorption capacity (up to 555.6 mg/g) via coprecipitation mechanisms. As-prepared biochar sample also can be prepared to a hydrogel with a remarkable mechanic strength. But biochar hydrogel decreases Pb adsorption capacity to 104.2 mg/g due to the pore blocking effect. Life cycle assessment illustrates that the scene of food scraps activated by CO2 has lower Global Warming Potential (GWP) and Primary Energy Demand (PED). Therefore, current research provides a high-efficiency method for treatment of food scraps.

Storage and separation of methane and carbon dioxide using platinum- decorated activated carbons treated with ammonia

Activated carbon (AC) was treated with ammonia for nitrogen doping and then was further anchored with platinum nanoparticles through ultrasound-assisted impregnation method. Methane (CH4) and carbon dioxide (CO2) storage of the pristine and modified activated carbon were determined at ambient temperature. All the samples showed high storage capacities with preference towards carbon dioxide storage, which would be favorable for both energy and environmental applications. Ammonia treatment slightly improved the storage of both CH4 and CO2 for all the samples, which could be attributed to the little improvement in the micropore properties upon nitrogen doping. Platinum decoration had an opposite influence on both CH4 and CO2 storage, which might be due to the absence of metal encouraging storage mechanism such as gas dissociation or reconstruction on platinum’s surface in addition to the harmful effect of metal pore-blocking and higher density of metal particles.