NEUTRALIZATION EFFECT OF THE FLY ASH AND COAL DUMP WASTES

Acidic and/or alkaline wastes, or wastes that change their pH level over time, create an increased danger to the environment and human population. These wastes can be formed due to activity of all basic branches of industry (agriculture, energy, metallurgy, food, chemical, mining, production and processing of petroleum products, etc.)

Revisiting the chemistry of graphite oxides and its effect on ammonia adsorption

Graphite oxide (GO) was synthesized using two different methods: one with sulfuric acid as part of the oxidizing mixture (Hummers-Offeman method) and another one without the sulfur-containing compound involved in the oxidation process (Brodie method). They were both tested for ammonia adsorption in dynamic conditions, at ambient temperature, and characterized before and after exposure to ammonia by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, potentiometric titration, energy-dispersive X-ray (EDX) spectroscopy, X-ray photoelectron spectroscopy (XPS) and elemental analysis. Analyses of the initial materials showed that besides epoxy, hydroxyl and carboxylic groups, a significant amount of sulfur is incorporated as sulfonic group for GO prepared by the Hummers-Offeman method. The process of ammonia adsorption seems to be strongly related to the type of GO. For GO prepared by the Brodie method, ammonia is mainly retained via intercalation in the interlayer space of GO and by reaction with the carboxylic groups present at the edges of the graphene layers. On the contrary, when GO prepared by the Hummers method is used, the ways of retention are different: not only is the intercalation of ammonia observed but its reaction with the epoxy, carboxylic and sulfonic groups present is also observed. In particular, during the ammonia adsorption process, sulfonic groups are converted to sulfates in the presence of superoxide anions O2-*. These sulfates can then react with ammonia to form ammonium sulfates. For both GOs, an incorporation of a significant part of the ammonia adsorbed as amines in their structure is observed as a result of reactive adsorption. © 2009 The Royal Society of Chemistry

CO2 interactions with porous carbons: Is the surface stable at ambient conditions?

Interactions of CO2 with polymer derived carbon/rGO composites at ambient conditions were studied. Both, dynamic adsorption tests and equilibrium adsorption measurements were analyzed. The samples differed in the porosity, oxidation level and speciation of sulfur on the surface. Even though more CO2 was adsorbed on the oxidized sample than in the unmodified one, the surface chemistry of the latter was found as having more pronounced effect on attracting CO2 to the pore system. The results showed the marked changes in S-doped nanoporous carbon composite surface chemistry upon CO2 adsorption at ambient conditions. The changes were more pronounced for carbon with higher density of sulfur in thiophenic configurations on the surface emphasizing the role of these species in CO2 reduction. Even though CO could not be the target of our detection, identification of water, SO and SO2 as products of surface reactions supports our hypothesis that CO2 adsorption was accompanied by some extent of its reduction to CO. CO is formed in the process of electron transfer from thiophenes to CO2 in which the former are oxidized forming sulfones and sulfonic acids. Those species are likely thermodynamically unstable and decompose forming SO/SO2 and water providing additional electrons for CO2 reduction. Conductivity of carbon matrix and the local increase in this feature owing to the presence of the graphene-based phase facilitate this process. Based on the results collected, it is recommended that the stability of carbons towards carbon dioxide should be evaluated before it is used as CO2 sequestration medium

Adsorption of Bovine Serum Albumin on Carbon-Based Materials

The protein adsorption plays a very important role in biotechnology, biomolecular engineering and it is one of the main factors determining bio- and hemocompatibility of biomedical materials in medical applications, such as blood purification and wound healing. Here we report adsorption properties of two carbon-based materials, thermally expanded graphite (EGr) and graphene nanoplatelets (GnP), for bovine serum albumin (BSA), the most abundant blood plasma protein. The influence of the surface chemistry of expanded graphite on the mechanism of BSA adsorption was studied by using EGr modified with oxygen or nitrogen functionalities. Having low microporosity and the specific surface area in the range of 5 to 50 m2/g, the expanded graphite exhibits high protein adsorption capacity at high equilibrium concentrations, which makes this material a potential candidate for biomedical applications as a carrier for high molecular weight (HMW) drug delivery or adsorption of HMW metabolites. At low equilibrium concentrations, the effect of specific protein-surface functional groups interaction reveals the differences between the adsorption affinity of different surface modified EGr materials to BSA. The adsorption of BSA on GnP with a specific surface area of 286 m2/g and a developed micro-/mesoporous structure did not follow the same mechanism as seen with EGr materials. At low equilibrium concentration of BSA, GnP exhibits high adsorption efficiency. An important finding is that no release of nanoparticles from expanded graphite adsorbents was observed, which makes them potentially suitable for direct contact with blood and other tissues while very small nanoparticles were noticed in the case of graphene nanoplatelets

Sulfur-mediated photochemical energy harvesting in nanoporous carbons

This work provides new insights in the field of applied photochemistry based on semiconductor-free nanoporous carbons and its application to sunlight energy harvesting. Using carbon materials of increasing average pore size, chemical functionalization to introduce a variety of O- and S-containing functional groups and monochromatic light, we have shown the dependence of the photochemical conversion of phenol in the confinement of the carbons nanopore space with the wavelength of the irradiation source, the dimensions of the pore voids and their surface chemistry. The photochemical conversion of phenol inside the carbons pore space was found to be very sensitive to the nature of the S-containing groups and the confinement state of the adsorbed pollutant.COA thanks the financial support of the European Research Council through a Consolidator Grant (ERC-CoG-648161-PHOROSOL) and the Spanish MINECO (CTM2014/56770-R). AGB thanks her PhD fellowship (BES-2012-060410). TJB acknowledges the NSF support (CBET 1133112).Peer reviewe

Sulfur-mediated photochemical energy harvesting in nanoporous carbons

This work provides new insights in the field of applied photochemistry based on semiconductor-free nanoporous carbons and its application to sunlight energy harvesting. Using carbon materials of increasing average pore size, chemical functionalization to introduce a variety of O- and S-containing functional groups and monochromatic light, we have shown the dependence of the photochemical conversion of phenol in the confinement of the carbons nanopore space with the wavelength of the irradiation source, the dimensions of the pore voids and their surface chemistry. The photochemical conversion of phenol inside the carbons pore space was found to be very sensitive to the nature of the S-containing groups and the confinement state of the adsorbed pollutant.COA thanks the financial support of the European Research Council through a Consolidator Grant (ERC-CoG-648161-PHOROSOL) and the Spanish MINECO (CTM2014/56770-R). AGB thanks her PhD fellowship (BES-2012-060410). TJB acknowledges the NSF support (CBET 1133112)

MXene Sorbents for Removal of Urea from Dialysate: A Step toward the Wearable Artificial Kidney

The wearable artificial kidney can deliver continuous ambulatory dialysis for more than 3 million patients with end-stage renal disease. However, the efficient removal of urea is a key challenge in miniaturizing the device and making it light and small enough for practical use. Here, we show that two-dimensional titanium carbide (MXene) with the composition of Ti3C2Tx, where Tx represents surface termination groups such as −OH, −O–, and −F, can adsorb urea, reaching 99% removal efficiency from aqueous solution and 94% from dialysate at the initial urea concentration of 30 mg/dL, with the maximum urea adsorption capacity of 10.4 mg/g at room temperature. When tested at 37 °C, we achieved a 2-fold increase in urea removal efficiency from dialysate, with the maximum urea adsorption capacity of 21.7 mg/g. Ti3C2Tx showed good hemocompatibility; it did not induce cell apoptosis or reduce the metabolizing cell fraction, indicating no impact on cell viability at concentrations of up to 200 μg/mL. The biocompatibility of Ti3C2Tx and its selectivity for urea adsorption from dialysate open a new opportunity in designing a miniaturized dialysate regeneration system for a wearable artificial kidney

Важливість молекулярно-генетичних досліджень при гіпохромній мікроцитарній анемії, рефрактерній до феротерапії, у діагностиці еритропоетичної протопорфірії

Еритропоетична протопорфірія (ЕПП) є рідкісним спадковим захворюванням, зареєстрованим в усьому світі, проте існують регіональні відмінності у його епідеміології. Хвороба спричиняється частковим дефіцитом ферохелатази, яка є останнім ферментом шляху біосинтезу гему. При типовій ЕПП світлочутливість з’являється вже після першого перебування в ранньому дитинстві на сонці. У 20–60% пацієнтів з ЕПП спостерігається мікроцитарна анемія, яку помилково первинно діагностують як залізодефіцитну анемію, тому призначають залізовмісні ліки. Мета - описати клінічний випадок рефрактерної до препаратів заліза гіпохромної мікроцитарної анемії в чотиримісячного хлопчика для поліпшення діагностики ЕПП. Клінічний випадок. Описано хворобу в чотиримісячного хлопчика, яка дебютувала з рефрактерної до застосування препаратів заліза гіпохромної мікроцитарної анемії. У мазку периферичної крові виявлено мішенеподібні еритроцити. Показники обміну заліза були в нормі, спостерігалося незначне збільшення селезінки. Акцент у публікації зроблено на диференційній діагностиці, профілактичних заходах і сучасному патогенетичному лікуванні за новітніми підходами, націленими на вирішення основних дефектів на молекулярному або клітинному рівні, з перспективою на значне поліпшення результатів лікування цього орфанного захворювання. Верифікацію захворювання проведено за допомогою секвенування геному, виявлено гетерозиготну патогенну мутацію FECH c.315-48T>C, характерну для ЕПП, яку дитина отримала від батька. Досвід лікування рефрактерної до препаратів заліза гіпохромної мікроцитарної анемії в чотиримісячного хлопчика дав підстави з диференціально-діагностичною метою розширити спектр обстежень, включаючи електрофорез гемоглобіну та застосування молекулярно-генетичних досліджень. Повідомлення про наведений клінічний випадок матиме інформаційну цінність для сімейних лікарів, педіатрів, гематологів та широкого кола спеціалістів. Дослідження виконано відповідно до принципів Гельсінської декларації. На проведення досліджень отримано інформовану згоду батьків дитини. Автори заявляють про відсутність конфлікту інтересів

Enhancement of Ti3C2 MXene Pseudocapacitance after Urea Intercalation Studied by Soft X ray Absorption Spectroscopy

MXenes have shown outstanding properties due to their highly active hydrophilic surfaces coupled with high metallic conductivity. Many applications rely on the intercalation between Ti3C2Tx Tx describes the OH, F and O surface terminations flakes by ions or molecules, which in turn might alter the Ti3C2Tx surface chemistry and electrochemical properties. In this work, we show that the capacitance, rate capability, and charge carrier kinetics in Ti3C2Tx MXene electrodes are remarkably enhanced after urea intercalation u Ti3C2Tx . In particular, the areal capacitance increased to 1100 mF cm2, which is 56 higher than that of pristine Ti3C2Tx electrodes. We attribute this dramatic improvement to changes in the Ti3C2Tx surface chemistry upon urea intercalation. The oxidation state and the oxygen bonding of individual Ti3C2Tx flakes before and after urea intercalation are probed by soft X ray absorption spectroscopy XAS at the Ti L and O K edges with 30 nm spatial resolution in vacuum. After urea intercalation, a higher Ti oxidation state is observed across the entire flake compared to pristine Ti3C2Tx. Additionally, in situ XAS of u Ti3C2Tx aqueous dispersions reveal a higher Ti oxidation similar to dry samples, while for pristine Ti3C2Tx the Ti atoms are significantly reduced in water compared to dry sample

Synergistic relationship between the three-dimensional nanostructure and electrochemical performance in biocarbon supercapacitor electrode materials

A novel study presented herein correlates the multidimensional morphology with the electrochemical performance of activated bio-carbon materials, for supercapacitor devices over multiple length scales. The optimization of the potassium hydroxide (KOH)/cellulose ratio for supercapacitor electrode materials is related to morphological characteristics and corresponding electrochemical performance, as described in terms of porosity, specific surface area, specific capacitance and electrochemical impedance. KOH/cellulose samples with ratios 0.5 : 1 and 1 : 1 exhibited the best performance, characterized by a hierarchal porous network structure, high surface area and low cell resistance. Compared with the rest of the manufactured samples and commercial activated carbons, Ketjen Black (KB), Norit activated carbon (NAC) and bead-shaped activated carbon (BAC), the former two samples showed better results in three-electrode systems and coin cells, with specific gravimetric capacitances as high as 187 F g−1 at a current density of 1 A g−1. The high performance is attributed to the morphology of the samples that constituted a combination of micro-, meso- and macroporosity which consequently gave high specific surface area, high porosity, low cell resistance and high specific capacitance. This further corroborates the structure-performance relationship observed in the author's model KOH/cellulose system, highlighting that the work can be extended to other similar systems. It is clear that the three-dimensional nanostructure of a material must be understood in its entirety in order to optimize the electrochemical performance