Epitomizing biohydrogen production from microbes: Critical challenges vs opportunities.

Hydrogen is a clean and green biofuel choice for the future because it is carbon-free, non-toxic, and has high energy conversion efficiency. In exploiting hydrogen as the main energy, guidelines for implementing the hydrogen economy and roadmaps for the developments of hydrogen technology have been released by several countries. Besides, this review also unveils various hydrogen storage methods and applications of hydrogen in transportation industry. Biohydrogen productions from microbes, namely, fermentative bacteria, photosynthetic bacteria, cyanobacteria, and green microalgae, via biological metabolisms have received significant interests off late due to its sustainability and environmentally friendly potentials. Accordingly, the review is as well outlining the biohydrogen production processes by various microbes. Furthermore, several factors such as light intensity, pH, temperature and addition of supplementary nutrients to enhance the microbial biohydrogen production are highlighted at their respective optimum conditions. Despite the advantages, the amounts of biohydrogen being produced by microbes are still insufficient to be a competitive energy source in the market. In addition, several major obstacles have also directly hampered the commercialization effors of biohydrogen. Thus, this review uncovers the constraints of biohydrogen production from microbes such as microalgae and offers solutions associated with recent strategies to overcome the setbacks via genetic engineering, pretreatments of biomass, and introduction of nanoparticles as well as oxygen scavengers. The opportunities of exploiting microalgae as a suastainable source of biohydrogen production and the plausibility to produce biohydrogen from biowastes are accentuated. Lastly, this review addresses the future perspectives of biological methods to ensure the sustainability and economy viability of biohydrogen production.

Assessment of agricultural waste-derived activated carbon in multiple applications.

To minimize waste production and reduce reliance on fossil fuels, agricultural waste such as rice straw has been actively used in biochemical production. In Taiwan, cellulosic waste has been used in anaerobic digestion for bioethanol production. This process produces a large amount of biomass-associated sludge that may become a serious environmental issue. Therefore, in this study, the anaerobic digestion sludge was recycled for the production of activated carbon via pyrolysis and activation by KOH. Surface characterization showed increased surface area and development of microporous structure upon activation. The FTIR image showed that high temperature activation eliminated most functional groups in the activated carbon, except for CO and C-O groups. The results showed that the activated carbon could be used for pollutant adsorbents such as molecular dyes (methylene blue: 217 mg g-1) and metal ions (copper: 169 mg g-1) from aqueous solution. In addition, the as-synthesized activated carbon can be used for CO2 capture and capacitor. Instead of focusing on one single application, we proposed that centralized production of activated carbon could be used in various applications, while further modification could be adopted depending on the need of its specific application.

Mercury adsorption and re-emission inhibition from actual WFGD wastewater using sulfur-containing activated carbon.

A series of batch experiments were conducted to obtain the optimal adsorption condition for removing aqueous Hg from actual lime-based wet flue gas desulfurization (WFGD) wastewater with sulfur-containing activated carbon (SAC). The experimental results showed that SAC1 had an average 0.32 µg mg-1 larger aqueous Hg adsorption capacity and 21% larger Hg removal than the CS2-treated SAC1 (i.e., SAC2) in all tested pH values, confirming that greater sulfur content associated with effective sulfur functional group (i.e., elemental S) caused the larger Hg adsorption capacity. Furthermore, as increasing pH from 4 to 7, the Hg adsorption capacity of SAC1 decreased by 22% (i.e., 0.27 µg mg-1). The equilibrium Hg adsorption capacity was well fitted with linear and Freundlich adsorption isotherms. Kinetic simulations showed that both pseudo-second order and Elovich equations could well describe the chemisorption behavior of Hg to SAC1. Thermodynamic parameter calculation confirmed that Hg adsorption by SAC1 was thermodynamically spontaneous and exothermic. Re-emission of gaseous Hg markedly decreased by 88% as SO32- addition increased from 0 to 0.01 mM. Notably, by the addition of SAC1, zero re-emission of gaseous Hg was achieved. These experimental results confirm that the capture of aqueous Hg2+ and the inhibition of gaseous Hg0 re-emission can be successfully and simultaneously achieved in actual WFGD wastewater via the addition of SAC.

Antimicrobial effects of zero-valent iron nanoparticles on gram-positive Bacillus strains and gram-negative Escherichia coli strains.

BACKGROUND: Zero-valent iron nanoparticles (ZVI NPs) have been used extensively for the remediation of contaminated soil and groundwater. Owing to their large active surface area, they serve as strong and effective reductants. However, the ecotoxicity and bioavailability of ZVI NPs in diverse ecological media have not been evaluated in detail and most studies have focused on non-nano ZVI or Fe0. In addition, the antimicrobial properties of ZVI NPs have rarely been investigated, and the underlying mechanism of their toxicity remains unknown. RESULTS: In the present study, we demonstrate that ZVI NPs exhibited significant toxicity at 1000 ppm against two distinct gram-positive bacterial strains (Bacillus subtilis 3610 and Bacillus thuringiensis 407) but not against two gram-negative strains (Escherichia coli K12 and ATCC11634). Specifically, ZVI NPs caused at least a 4-log and 1-log reductions in cell numbers, respectively, in the two Bacillus strains, whereas no change was detected in the two E. coli strains. X-ray photoelectron spectroscopy, X-ray absorption near-edge, and extended X-ray absorption fine structure spectra confirmed that Bacillus cells exposed to ZVI NPs contained mostly Fe2O3 with some detectable FeS. This finding indicated that Fe0 nanoparticles penetrated the bacterial cells, where they were subsequently oxidized to Fe2O3 and FeS. RedoxSensor analysis and propidium iodide (PI) staining showed decreased reductase activity and increased PI in both Bacillus strains treated with a high (1000 ppm) concentration of ZVI NPs. CONCLUSION: Taken together, these data show that the toxicity of ZVI NPs was derived from their oxidative properties, which may increase the levels of reactive oxygen species and lead to cell death.

pH-Dependent Antimicrobial Properties of Copper Oxide Nanoparticles in Staphylococcus aureus.

The antimicrobial properties of CuO nanoparticles have been investigated, but the underlying mechanisms of toxicity remain the subject of debate. Here, we show that CuO nanoparticles exhibit significant toxicity at pH 5 against four different Staphylococcus aureus (S. aureus) strains, including Newman, SA113, USA300, and ATCC6538. At this pH, but not at pH 6 and 7, 5 mM CuO nanoparticles effectively caused reduction of SA113 and Newman cells and caused at least 2 log reduction, whereas 20 mM killed most strains but not USA300. At 5 mM, the nanoparticles were also found to dramatically decrease reductase activity in SA113, Newman, and ATCC6538 cells, but not USA300 cells. In addition, analysis of X-ray absorption near-edge structure and extended X-ray absorption fine structure confirmed that S. aureus cells exposed to CuO nanoparticles contain CuO, indicating that Cu2+ ions released from nanoparticles penetrate bacterial cells and are subsequently oxidized intracellularly to CuO at mildly acidic pH. The CuO nanoparticles were more soluble at pH 5 than at pH 6 and 7. Taken together, the data conclusively show that the toxicity of CuO nanoparticles in mildly acidic pH is caused by Cu2+ release, and that USA300 is more resistant to CuO nanoparticles (NPs) than the other three strains.

Synthesis, fine structural characterization, and CO2 adsorption capacity of metal organic frameworks-74.

Two metal organic frameworks of MOF-74 group (zinc and copper-based) were successfully synthesized, characterized, and evaluated for CO2 adsorption. The both samples such as MOF-74(Zn) and MOF-74(Cu) were characterized with FE-SEM for morphology and particle size, XRD patterns for phase structure, FTIR for organic functional groups, nitrogen adsorption for pore textural properties, and X-ray absorption spectroscopy for fine structural parameters and oxidation states of central metal atoms. CO2 adsorption isotherms of MOF-74 samples were measured in a volumetric adsorption unit at 273 K and pressure up to 1.1 bar. The MOF-74(Zn) and MOF-74(Cu) adsorbents have the pore widths of 8.58 and 8.04 angstroms with the BET specific surface areas of 1,474 and 1,345 m2 g(-1), respectively. CO2 adsorption capacities of MOF-74(Zn) and MOF-74(Cu) were 4.10 and 3.38 mmol x g(-1), respectively measured at 273 K and 1.1 bar. The oxidation state of central atoms in MOF-74(Zn) was Zn(II) confirmed by XANES spectra while MOF-74(Cu) was composed of Cu(I) and Cu(II) central atoms. The bond distances of Zn--O and Cu--O were 1.98 and 1.94 angstroms, respectively.

Structural characterization and adsorption properties of pluronic F127 onto iron oxides magnetic nanoparticles.

Superparamagnetic iron oxide nanoparticles coated with polymers have shown low toxicity and chemical stability in physiological condition, thereby can be used to deliver encapsulated drugs throughout the body by external magnetic fields. In this study, magnetic nanoparticles were synthesized thorough co-precipitation method and their interaction with Pluronic F127 block copolymer as well as adsorption properties of polymer onto nanoparticles were investigated. Adsorption measurement revealed different adsorption behaviors below and above the polymer's critical micelle concentration. The Freundlich isotherm was found to better describe the adsorption behavior of Pluronic F127 onto SIONPs particles below the block copolymer critical micelle concentration. At higher concentration, the adsorbed amount is likely to diminish due to interpenetration of the adsorbed macromolecular micelles and volume-excluded effects for block copolymers. Furthermore, magnetic nanocomposites with different concentration of polymers were prepared through hydrothermal method. The crystalline structure, morphology, pore structure, and magnetic properties of magnetic nanoparticles/nanocomposites products at different pH and polymer concentration were studied. Results showed that due to the hematite impurities, magnetic nanocomposites synthesized at higher pH have lower magnetization.

Synthesis, characterization, and hydrogen storage enhancement of M2(BDC)2dabco with palladium-doped activated carbon.

Two bi-organic type metal organic frameworks (MOFs) such as Co2(BDC)2dabco and Zn2(BDC)2 dabco have been synthesized by hydrothermal method and characterized along with hydrogen adsorption. The hydrogen adsorption capacity of these MOFs was increased after doping by palladium-activated carbon. Co2(BDC)2dabco has cracked and folded thin film like surface while Zn2(BDC)2dabco has a brick-typed cubic structure with particle size about 10-15 microm identified by FE-SEM. The XRD patterns represents that both MOFs have the well crystalline structure. Nitrogen adsorption isotherms show that both structures have Type I adsorption isotherm with the BET specific surface area of 1,390 and 1,433 m2 g(-1) for Co2(BDC)2dabco and Zn2(BDC)2dabco, respectively. Pristine Co2(BDC)2dabco and Zn2(BDC)2dabco can store about 0.22 and 0.25 wt.% of H2 measured at 298 K and 32 bar. This capacity was greatly enhanced by doping palladium-activated carbon to 0.31 and 0.41 wt.%, respectively. Moreover, both structures were also characterized by XANES/EXAFS. EXAFS spectra indicate that Co2(BDC)2dabco has the Co--O bond distance of 2.030 A with the coordination number of 4.2 while Zn2(BDC)2dabco has 2.015 angstroms bond distance of Zn--O with the coordination number of 3.4.

Utilization of carbon-based nanomaterials for wastewater treatment and biogas enhancement: A state-of-the-art review.

The management of environmental pollution and carbon dioxide (CO2) emissions is a challenge that has spurred increased research interest in determining sustainable alternatives to decrease biowaste. This state-of-the-art review aimed to describe the preparation and utilization of carbon-based nanomaterials (CNM) for biogas enhancement and wastewater contaminant (dyes, color, and dust particles) removal. The novelty of this review is that we elucidated that the performance of CNMs in the anaerobic digestion (AD) varies from one system to another. In addition, this review revealed that increasing the pyrolysis temperature can facilitate the transition from one CNM type to another and outlined the methods that can be used to develop CNMs, including arc discharge, chemical exfoliation, and laser ablation. In addition, this study showed that methane (CH4) yield can be slightly increased (e.g. from 33.6% to 60.89%) depending on certain CNM factors, including its type, concentration, and feedstock. Temperature is a fundamental factor involved in the method and carbon sources used for CNM synthesis. This review determined that graphene oxide is not a good additive for biogas and CH4 yield improvement compared with other types of CNM, such as graphene and carbon nanotubes. The efficacy of CNMs in wastewater treatment depends on the temperature and pH of the solution. Therefore, CNMs are good adsorbents for wastewater contaminant removal and are a promising alternative for CO2 emissions reduction. Further research is necessary to determine the relationship between CNM synthesis and preparation costs while accounting for other factors such as gas flow, feedstock, consumption time, and energy consumption.

Mineralization of SF6 and NF3 fluorinated compounds for greenhouse gas abatement by oxalates.

Fluorinated compounds (FCs) such as sulfur hexafluoride (SF6) and nitrogen trifluoride (NF3) have garnered attention due to their environmental impact. This study investigates the mineralization and removal of two potent FCs: SF6 and NF3. The results confirm that utilizing various oxalate salts leads to the formation of corresponding metallic fluorides: lithium fluoride (LiF), sodium fluoride (NaF), and potassium fluoride (KF), validating the occurrence of mineralization reactions. Among the oxalate salts, sodium oxalate demonstrates the highest mineralization efficiency in both SF6 and NF3 removal. Real-time Fourier transform infrared spectroscopy (FT-IR) gas-phase analysis confirms rapid and complete gas removal within a short reaction time using the selected oxalate salts. Meticulous mass balance calculations revealed that oxalates (LiF, NaF, and KF) yielded sulfur (S) at rates of 92.09%, 91.85%, and 84.98% following SF6 mineralization. Additionally, the conversion rates of oxalates to the corresponding metallic fluorides (LiF, NaF, and KF) after SF6 mineralization were 98.18%, 95.82%, and 95.21%, respectively. Similarly, after NF3 mineralization, these conversion rates stood at 92.18%, 90.67%, and 90.02%, respectively. The removal efficiencies for SF6 (1000 ppm) were 4.98, 12.01, and 7.23 L/g, while those for NF3 (1000 ppm) were 14.1, 12.6, and 11.7 L/g, respectively. Notably, sodium oxalate exhibits superior effectiveness, achieving 100% SF6 conversion within 30 min and 100% NF3 conversion within 50 min. This work underscores the potential of oxalate mineralization as a promising strategy for efficient and rapid removal of potent fluorinated compounds, paving the way for environmentally benign FC remediation techniques with broader implications for sustainable gas treatment technologies.

Investigation of Lithium-Ion Battery Performance Utilizing Magnetic Controllable Superionic Conductor Li3(V1-x Fe x )2(PO4)3/C (x = 0.05 and 0.10).

Lithium-ion batteries with Li3V2(PO4)3/C as the cathode have been a popular research topic in recent years; however, studies of the effects of external magnetic fields on them are less common. This study investigates the effects of an external magnetic field applied parallel to the direction of the anode and cathode on the ion transport through iron-doped Li3(V1-x Fe x )2(PO4)3, the outer carbon coating, the film/electrolyte/separator, and up to the lithium metal electrode on a microscopic level. The results reveal that for the x = 0.05 sample with lower doping, the magnetostriction expansion of Li3(V1-x Fe x )2(PO4)3 and the magnetostrictive contraction effect of the outer ordered carbon layer cancel each other out, resulting in no significant enhancement of the battery's energy and power density due to the external magnetic field. In contrast, the x = 0.1 sample, lacking magnetostrictive contraction in the outer ordered carbon layer, shows that its energy and power density can be influenced by the magnetic field. Under zero magnetic field, the cyclic performance exhibits superior average capacity performance in the x = 0.05 sample, while the x = 0.1 sample shows a lower decay rate. Both samples are affected by the magnetic field; however, the x = 0.1 sample performs better under magnetic conditions. In particular, in the C-rate tests under a magnetic field, the sample with x = 0.1 showed a significant relative reduction in capacity decay rate by 20.18% compared to the sample with x = 0.05.

Synthesis and characterization of nickel and zinc ferrite nanocatalysts for decomposition of CO2 greenhouse effect gas.

The decomposition of CO2 over oxygen deficient nickel ferrite nanoparticles (NFNs) and zinc ferrite nanoparticles (ZFNs) at 573 K was studied. The oxidation states with fine structure of Fe/Ni or Fe/Zn species were also measured in NFNs and ZFNs catalysts, respectively. Oxygen deficiency of catalysts was obtained by reduction in hydrogen. Decomposition of CO2 into carbon and oxygen has been carried out within few minutes when it comes into contact with oxygen deficient catalysts through incorporation of oxygen into ferrite nanoparticles. Oxygen and carbon rather than CO were produced in the decomposition process. The complete decomposition of CO2 was possible because of higher degree of oxygen deficiency andsurface-to-volume ratio of the catalysts. The pre-edge XANES spectra of Fe species in both catalysts exhibit an absorbance feature at 7114 eV for the 1s to 3d transition which is forbidden by the selection rule in case of perfect octahedral symmetry. The EXAFS data showed that the NFNs had two central Fe atoms coordinated by primarily Fe-O and Fe-Fe with bond distances of 1.871 and 3.051 angstroms, respectively. In case of ZFNs these values are 1.889 and 3.062 A, respectively. Methane gas was produced during the reactivation of NFNs by flowing hydrogen gas. Decomposition of CO2, moreover, recovery of valuable methane using heat energy of offgas produced from power generation plant or steel industry is an appealing alternative for energy recovery.

Preparation, characterization, and hydrogen storage capacity of MIL-53 metal-organic frameworks.

Metal organic frameworks (MOFs) are considered as most promising candidate for hydrogen storage material for practical application. MIL-53(Cr) MOFs were synthesized from Cr(NO3)3 x 9H2O combined with terephthalic acid organic linker. MIL-53(Cr) MOFs are octahedral in shape and the particle size was around 10 microm identified by FE-SEM. The cleaning of the MOFs crystals with different solvents at different warm temperature were found effective and approved to increase the specific surface area and porosity of MIL-53(Cr) MOFs. The XRD patterns represented that MIL-53(Cr) MOFs had well crystalline structures. Nitrogen adsorption isotherms show that Mil-53(Cr) has approximately type-I isotherm with a highest BET specific surface area of 1946 m2 g(-1) after treated with hot methanol. Hydrogen adsorption study shows that this material can store 0.45 wt.% of H2 measured at 303 K and 32 bar. The pre-edge XANES spectra confirm the existence of Cr(III) in crystalline framework of MIL-53(Cr) and the sharp feature at 6007 eV in XANES spectra represents the dipole-allowed electron transition from 1s to 4p(xy). In addition, EXAFS spectra indicate that MIL-53(Cr) metal organic frameworks structure has the Cr-O bond distance of 1.96 angstroms with a coordination number of 5.4.

Synthesis and characterization of porous zero-valent iron nanoparticles for remediation of chromium-contaminated wastewater.

The physical and chemical properties of porous zero-valent iron nanoparticles (ZVINs) have highly been acknowledged in the decontamination of heavy metal containing wastes and groundwater. In the present work, the treatment of Cr-contaminant through adsorption onto the ZVINs has been studied. The morphology, crystal structure, and surface composition of Fe(O) nanoparticles were investigated by field emission scanning electron microscopy/energy dispersive X-ray spectroscopy (FE-SEM/EDS), transmission electron microscope (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS), respectively. X-ray absorption near edge structure (XANES) revealed that the Cr(VI) species reduce to Cr(III) while oxidizing the ZVINs to Fe2O3, Fe3O4 or FeO electrochemically. Furthermore, the nitrogen adsorption-desorption isotherm of the porous nanoparticles was similar to a type IV curve with an obvious mesopore-characteristic H3 hysteresis loop, whereas the sizes of mesopores were in the range of 30-50 nm. Experimentally, the efficiency for Cr(VI) removal in the range of 150-300 ppm was found to be > 99.9%. Remarkably, the reduction reaction was completed within 10 min in the absence of additional pH controls. This work also highlights the utility of X-ray absorption spectroscopy (XAS) coupled with conventional characterization methods to comprehensively study the speciation and possible reaction pathway in adsorption process.

Advancement of biochar-aided with iron chloride for contaminants removal from wastewater and biogas production: A review.

The use of fossil fuels, emission of greenhouse gases (GHG) into the atmosphere, and waste pose a problem to the environment and public health that urgently needs to be dealt with. Among numerous chemical activating agents that can be added to anaerobic digestion (AD) to enhance nutrient removal and increase the quality and quantity of biomethane, iron chloride (FeCl3) is the one that has the lowest cost and is the most environmentally friendly. This state-of-the-art review aims to revise the influence of FeCl3 on the Brunauer-Emmett-Teller (BET) surface area of biochar and its ability to increase methane (CH4) yield and remove contaminants from biogas and wastewater. The novelty of the study is that FeCl3, an activating agent, can increase the BET surface area of biochar, and its efficacy increases when combined with zinc chloride or phosphoric acid. Regarding the removal of contaminants from wastewater and biogas, FeCl3 has proven to be an effective coagulant, reducing the chemical oxygen demand (COD) of wastewater and hydrogen sulfide in biogas. The performance of FeCl3 depends on the dosage, pH, and feedstock used. Therefore, FeCl3 can increase the BET surface area of biochar and CH4 yield and remove contaminants from wastewater and biogas. More research is needed to investigate the ability of FeCl3 to remove water vapor and carbon dioxide during biogas production while accounting for a set of other parameters, including FeCl3 size.

Green synthesis and characterization of silicate nanostructures coated with Pluronic F127/gelatin for triggered drug delivery in tumor microenvironments.

Thermo-/pH-sensitive nanocomposites based on mesoporous silicate MCM-41 (MSNCs) derived from rice husk ash were synthesized and characterized. MSNCs were coated with thermo-/pH-sensitive Pluronic® F127 and gelatin to form MSNCs@gp nanocomposites, serving as carriers for controlled release of the anticancer drug doxorubicin (Dox). The in vitro and in vivo antitumor efficacy of MSNCs@gp-Dox against liver cancer was evaluated. Fourier-transform infrared (FTIR) spectra confirmed the silica nature of MSNCs@gp by detecting the Si-O-Si group. Under acidic microenvironments (pH 5.4) and 42 °C, MSNCs@gp-Dox exhibited significantly higher Dox release (47.33 %) compared to physiological conditions. Thermo-/pH-sensitive drug release (47.33 %) was observed in simulated tumor environments. The Makoid-Banakar model provided the best fit at pH 7.4 and 37 °C with a mean squared error of 0.4352, an Akaike Information Criterion of 15.00, and a regression coefficient of 0.9972. Cytotoxicity tests have demonstrated no significant toxicity in HepG2 cells treated with various concentrations of MSNCs@gp, while MSNCs@gp-Dox induced considerable cell apoptosis. In vivo studies in nude mice revealed effective suppression of liver cancer growth by MSNCs@gp-Dox, indicating high pharmaceutical efficacy. The investigated MSNCs@gp-based drug delivery system shows promise for liver cancer therapy, offering enhanced treatment efficiency with minimal side effects.

Haitians' perceptions of biogas produced via human excreta: An approach to the democratization of energy systems.

The utilization of organic matter (OM) to produce biogas is an attractive alternative for promoting sustainable development, addressing energy shortages and waste disposal problems, creating jobs, and investing in sanitation systems. Thus, this alternative is becoming increasingly important in developing countries. This study investigated the perceptions of residents in Delmas district, Haiti, regarding the use of biogas produced via human excreta (HE). A questionnaire containing closed- and open-ended questions was administered for this purpose. Sociodemographic aspects had no influence on locals' willingness to use biogas produced via different types of OM. The novelty of this research is that democratization and decentralization of the energy system are possible in the Delmas district using biogas produced from various organic wastes. Socio-characteristics of the interviewees did not influence their willingness towards a possible adopt biogas-based energy from several types of degradable organic matter. The results showed that more than 96% of the participants agreed that HE could be used to produce biogas and reduce energy shortages in their locality. In addition, 93.3% of the interviewees thought this biogas could be utilized for cooking food. However, 62.5% of respondents argued that using HE to produce biogas could be dangerous. Bad smell and fear of biogas produced via HE are the major concerns of users. In conclusion, this research could guide stakeholders' decisions to better address the problems of waste disposal and energy shortages and to create new jobs in the target study area. The research findings could help decision-makers better understand the willingness of locals to invest in household digester programs in Haiti. Further research is required to investigate farmers 'willingness to use digestates from biogas production.

High-Temperature Syngas Desulfurization and Particulate Filtration by ZnO/Ceramic Filters.

Combustible gas (e.g., gasification syngas) cleaning at high temperatures can obtain further gains in energy efficiency for power generation and importantly leads to a simplified process and lower cost as a commercially viable source of clean energy. Thus, a feasibility study for high-temperature desulfurization (HTDS) and additional high-temperature particulate filtration (HTPF) of a raw syngas using ZnO sorbent-dispersed Raney CuO (ZnO/R-CuO) and ceramic filter (ZnO/CF) has been carried out. By synchrotron X-ray absorption near-edge structure (XANES) spectroscopy, mainly Zn(II) and Cu(II) are found in the ZnO/R-CuO sorbents. Both ZnO and R-CuO in the sorbents are involved in HTDS (1% H2S) at 873 K to form ZnS, Cu2S, and a small amount of CuS and reach relatively high HTDS efficiencies (82-90%). In addition, regeneration of the sulfurized sorbent by oxidation with O2 at 873 K (HTRG) for 1 h can restore ZnO and CuO for continuous and repetitive HTDS-HTRG cycles. To facilitate the HTDS engineering applications by the ZnO/R-CuO sorbents, their reaction rate constant (8.35 × 104 cm3/g/min) and activation energy (114.8 kJ/mol) at 873 K have also been determined. Furthermore, the ZnO/CF sorbent/filter can perform HTDS and additional HTPF at 873 K with very high particulate removal efficiencies (>98%). This demonstrates the feasibility for hot-syngas cleaning with a much better energy efficiency and lesser cost for cleaner power generation.

Thermal-/pH-triggered hollow mesoporous carbon nanocarrier for NIR-responsive drug release.

Intelligent drug-delivery systems are considered one of the most important techniques for improving cancer treatment using existing over-the-counter medicines. However, metallic materials are always accompanied by metabolism problems, whereas chemotherapy produces several side effects in humans. Carbon-based materials exhibit exceptional features such as bio-affinity and bio-degradability. Herein, hollow mesoporous carbon nanoparticles (HMCs) are reported as effective nanocarriers of anti-cancer small drug molecules. Near IR (NIR) sources, which can penetrate most organs, induce thermal effects via non-invasive pathways. NIR radiation not only provides thermal therapy but also is compatible with temperature-sensitive coated responsive polymer shells. The template method was used to synthesize HMCs with size 200 ± 50 nm, under various conditions, to obtain suitably sized and hollow structures for liver-cancer treatment. Additional pH/thermal-bi-responsive poly(N-isopropylacrylamide) (PNIPAM) shells were further coated onto the HMCs to produce multiple shells that could trigger swelling motions in PNIPAM@HMCs, as confirmed via small-angle X-ray scattering (SAXS). NIR results demonstrated an extreme increase to the ∆T of 8.7 and 14.2 °C for HMC and PNIPAM@HMCs, respectively. The SAXS spectra analyzed using SasView simulations demonstrated the multi-shell structures of synthesized HMCs and the release mechanism of PNIPAM@HMCs. Based on the model simulation of SAXS, the different rates of polymer swelling indicated the core shrinkage (229.7 to 134.2 Å) and shell expansion (324.3 to 514.3 Å) at 37 °C and 42 °C, respectively. In addition, the first-order, Higuchi, Korsmeyer-Peppas, and Weibull mathematical models were used to verify the drug-release kinetics, and the model with the highest R2 value was considered most suitable for further application. This paper presents the first SAXS study on PNIPAM@HMCs release kinetics and related mechanisms. This phenomenon indicates NIR-induced PNIPAM@HMCs as an effective strategy for cancer treatment via doxorubicin release.

Synthesis and characterization of green rust-deposited MoS2 composites for adsorptive removal of EDTA-chelated Ni(II) in wastewater.

Ethylenediamminetetraacetatonickel(II) (EDTA-Ni(II)) has emerged as a significant soil and groundwater contaminant due to the increasing agricultural and industrial activities, posing environmental challenges. This study focuses on addressing the reactivity of green rust (GR), which can be hindered by oxidation with oxygen, limiting its effectiveness in remediation processes. To overcome this limitation and enhance the adsorptive capacities, the combination of sulfate green rust (SO4-GR) with various Fe(II)/Fe(III) ratios with a high-surface-area adsorbent, MoS2, resulting in the formation of binary composites of green rust-deposited MoS2 (MSGs) were explored. The aim was to improve the removal efficiency of EDTA-Ni(II) from contaminated wastewater. To characterize the MSGs, a comprehensive analysis using XRD, SEM, TEM, FTIR, and X-ray absorption spectroscopy was performed. The surface areas of the MSGs were smaller than that of MoS2 but larger than that of the SO4-GRs, indicating a promising composite material. XANES spectra analysis revealed that both MSGs and SO4-GRs exhibited a mixture of ferrous and ferric ions, as evident from their spectral positioning between FeO and Fe2O3. The optimal pH for efficient removal of EDTA-Ni(II) was 3, which resulted in removal efficiencies of 45.6%, 47.3%, 46.0%, and 46.2% for MSG 1, MSG 2, MSG 3, and MSG 4 after 24 h, respectively. Reducing the initial concentration of EDTA-Ni(II) to 50 mg Ni(II)/L effectively doubled the removal efficiency. Notably, as EDTA-Ni(II) was removed, an increased leaching of iron was observed, leading to a total iron concentration exceeding 40 mg/L for the composites with higher Fe(II)/Fe(III) ratios. These findings underscore the potential of MSG as a promising material for degrading EDTA-Ni(II) in contaminated wastewater, offering a viable solution to mitigate the environmental impact of this emerging contaminant. This study contributes to the understanding of green rust reactivity and provides valuable insights for developing effective strategies to address the challenges associated with EDTA-Ni(II) contamination.