Breakthrough Sulfur Capacity Research Articles

CuY@NiAl-Layered double oxides bi-functional composites for “Catalytic–Adsorptive” removal of carbonyl sulfide

Carbonyl sulfide (COS) removal processes, typically containing catalytic hydrolysis and subsequent capture of hydrogen sulfide (H2S) generated, are energy-intensive and of high complexity. Bi-functional materials with the capability for synergistic catalytic conversion of COS and subsequent adsorption capture of H2S can enable effective removal of COS at low energy cost. Here, we report the development of a bi-functional CuY@NiAl-LDO composite material with integrated catalytic conversion of COS and adsorptive separation of H2S with high efficiency and stability. Fundamental material characterizations elucidate that the CuY@NiAl-LDO composite materials feature a core–shell structure. Coupled dynamic breakthrough experiments and DFT simulations highlight the unique synergistic “catalytic–adsorptive” effect between CuY and NiAl-LDO in the COS removal processes. Specifically, compared with the pure zeolite CuY and NiAl-LDO, the CuY@NiAl-LDO composites present significantly higher COS removal performance. The highest degree of desulfurization was observed on CuY@NiAl-LDO(46 %) at 80 °C with a breakthrough sulfur capacity of 20.57 mg-S/g and no detectable H2S in the outlet gas. In sum, this study highlights the synergistic “catalytic–adsorptive” mechanism of the bi-functional CuY@NiAl-LDO core–shell composite in desulfurization. The insights obtained may benefit chemical engineers by providing a new strategy for the development of multi-functional desulfurization materials.

Carbon nanofibers supported sorbents with enhanced performance via microwave-assisted in-situ structural modifications for H2S removal

The construction of sorbent with excellent structure and highly dispersed active components is vital to improving its desulfurization activity. Herein, the Fe nanoparticles/carbon nanofibers (Fe/CNFs) desulfurization sorbents were fabricated via electrospinning, template method and microwave carbonization. The structure of sorbents was successfully regulated with the adjustments of Fe content and the types of sacrificial phases. It was found that the Fe content impacted strongly on both structural and desulfurization performance of the sorbents. The sorbents with various Fe contents showed a trend of first increasing and then decreasing with the increased Fe content in breakthrough sulfur capacity. Among the various samples, the sample with the highest sulfur content was 7.21 g S/100 g sorbent. Furthermore, the Fe/CNFs sorbents were optimized via soft and hard template methods, by taking polymethyl methacrylate (PMMA) and SiO2 nanospheres as sacrificial phases. Desulfurization tests implied that the PMMA and SiO2 modified sorbents involved sulfur capacity of 13.76 and 14.18 g S/100 g sorbent, respectively. According to the characterizations, the modified sorbents were imparted with micro- and open-type macro-porous structure, respectively, upon which, the active components were uniformly dispersed and exposed. The excellent performance of sorbent could be attributed to the synergistic effect of porous structure and widely distributed Fe nanoparticles on CNFs. This work highlights new strategy for the synthesis of desulfurization sorbent.

Waste to wealth: Efficient wet desulfurization of electric arc furnace dust (EAFD) and recycling of desulfurization solid residue

In this study, we used calcined hazardous waste electric arc furnace dust (EAFD) as a desulfurizer for an effective wet desulfurization process. Testing for desulfurization efficacy revealed that the calcined EAFD, particularly when treated at 800 °C in an oxygen (O2) environment (termed EAFD-O2), achieved an unprecedented breakthrough sulfur capacity (BSC) of 3.71 gSO2·g−1 at 55 °C-the highest to date for EAFD applications in desulfurization efforts. Further investigation indicated that the calcination method expels certain volatile contaminants, thereby enhancing the crystallinity and lattice oxygen content of zinc oxide, the strong active phase of desulfurization in EAFD, which is principally responsible for the superior desulfurization results of EAFD-O2. Moreover, the observed reduction in the desulfurization slurry’s activity primarily stems from the depletion of the strong active phase of desulfurization (ZnO) and the resultant rise in the liquid phase’s sulfate concentration. Notably, the deactivated slurry’s solid residue predominantly consists of high-purity ZnFe2O4, a form of zinc ferrite utilized extensively for its proficiency in photocatalytic. Following straightforward processing, this substance displayed exceptional performance in photocatalytic-Fenton degradation tests on tetracycline (TC). In sum, the study not only turns hazardous EAFD into a powerful agent for removing SO2, a gaseous pollutant but also converts it into a value-added material, ZnFe2O4, thus proposing an integrated and efficient approach to solid waste management.

3D-interconnected N-doped porous carbon with hierarchical pore structure as a high-efficiency catalyst for H2S oxidation at room temperature

Nitrogen-doped porous carbons (NPCs) have been regarded as an efficient metal-free catalyst for H2S oxidation. However, critical factors affecting their desulfurization ability are still unclear, making it difficult to accurately adjust their desulfurization performance to meet industrial requirements. Herein, a novel 3D-interconnected NPC with hierarchical pore structure was synthesized by one-step “leavening” strategy using rice husk and (NH4)2C2O4 as a carbon source and foaming agent, respectively, for H2S oxidation at room temperature. Pyrolysis temperature is the major factor for physicochemical properties of NPCs, and breakthrough sulfur capacity of the optimal NPC reaches up to 1036.68 mg/g, which can remain stable during three desulfurization-regeneration cycles. Comparative experiment shows that H2S capacity of NPC is 1.8 and 4.0 times those of PC and NC, respectively, revealing the excellent desulfurization performance of NPC. The structure-effect relationships between H2S and NPC reveal that both textural and chemical properties of NPC, especially specific surface area, structural defect, and pyrrolic N, play dominant roles in H2S removal. It is very necessary to balance the relationship between textural performances and pyrrolic N to synthesize optimal NPC catalyst. This work provides a valuable reference for rational design of high-efficiency carbon-based catalysts for persistent desulfurization at room temperature.

Modulating oxygen vacancies of Fe-doped Ti-based materials with ultrathin nanosheets for enhancing H2S-to-S selective oxidation

Developing highly efficient catalysts for the transformation of hydrogen sulfide (H2S) pollutants into value-added products is crucial for both fundamental catalytic research and industrial chemistry. Herein, ferrititanate nanosheets (H0.8Ti1.2Fe0.8O4, denoted as NS-HTFO) exfoliated from lepidocrocite-type titanates are employed for the first time to catalyze the conversion of H2S to elemental sulfur. Collective experimental characterizations reveal that the as-designed NS-HTFO catalyst possesses ultrathin 2D structure and a large specific surface area, featuring abundant oxygen vacancies. Compared with its sandwich-like precursor of K0.8Ti1.2Fe0.8O4 (denoted as L-KTFO), the NS-HTFO catalyst displays notably enhanced desulfurization activity, achieving 100 % H2S conversion and over 93 % sulfur selectivity at temperatures ranging from 90 to 270 °C. Moreover, no significant decline in sulfur yield is observed over the course of a 100-hour evaluation, showing outstanding breakthrough sulfur capacity up to 4163 mg/gcat. This performance exceeds that of most recently reported catalysts. The possible catalytic mechanism for H2S-to-S selective oxidation over the NS-HTFO catalyst has also been investigated.

Desulfurization performance and mechanism for H2S from blast furnace gas over FAU zeolite sorbent

The desulfurization of blast furnace gas is crucial to meet the strict requirements for clean production of steel industry. However, the composition of blast furnace gas is complicated, and the gases of H2O, CO, CO2, and O2 would significantly affect the desulfurization activity. Therefore, the desulfurization performance for H2S in simulated blast furnace gas by Na-type FAU zeolites with different Si/Al was investigated. The physicochemical properties of zeolite sorbents were measured, and their correlation with desulfurization performance was studied. Moreover, the adsorption mechanism of H2S was investigated. The breakthrough sulfur capacity improved with the increase of relative crystallinity, Na+ content, specific surface area, and the decrease of Si/Al ratio. The adsorption mechanism of H2S on Na-type FAU zeolite was proposed. One is the hydrogen bond interaction between the bridging hydroxyl groups and H2S, and the other one is the base-acid interaction between sodium ion and H2S. In blast furnace gas, when interacting with Na+, H2S would be transformed into S, which further oxidized into thiosulfate and sulfate by O2.

In-situ regenerable Cu/Zeolite adsorbent with excellent H2S adsorption capacity for blast furnace gas

Desulfurization of blast furnace gas (BFG) is essential for steel companies to achieve its cleaner utilization. In this study, an in-situ regeneratable H2S adsorbent with a high sulfur capacity was developed. Zeolites with specific silica-aluminum ratios were selected, and hybrid Cu/zeolites adsorbents were synthesized using an impregnation method. The optimal adsorbent (DSZ-2) exhibited a high breakthrough sulfur capacity of 39.0 mg/g at 80 °C. Moreover, this adsorbent can also be in-situ regenerated at lower temperatures (280 ℃) and the regenerated adsorbent has even a higher breakthrough sulfur capacity of 49.0 mg/g. The possible desulfurization and regeneration mechanism of the DSZ-2 absorbent are discussed. Due to its high sulfur capacity and good regenerability, this absorbent has great application prospect in the removal of H2S from BFG.

Benign-by-design N-doped activated carbon from wasted aqueous assisted hydrochar of leftover rice for efficient H2S removal

The N-doped activated carbon is a potential material for H2S removal, reusing N-rich waste aqueous as a nitrogen source is promising to prepare in-expensive N-doped activated carbon. In this study, N-rich waste aqueous assisted hydrothermal carbonization and KOH activation were used to prepare activated carbon from starchy waste, concentrating on the effects of the nitrogen species (inorganic-N and organic-N) on the physicochemical characteristics and desulfurization performance of carbon material. Introducing inorganic-N (i.e., NH3·H2O) can increase the defect degree and enhance the formation of micropores and mesopores for N-doped activated carbon, leading to high storage ability for desulfurization products and well oxidation performance. The organic-N (i.e., alanine) was conducive to forming pyridinic-N and quinonyl for N-doped activated carbon, resulting in a strong ability of adsorption, dissolution, and oxidation for H2S. The organic-N determined the high breakthrough sulfur capacity for hydrothermal aqueous doping activated carbon (110.7 mg/g), which was ∼ 4.08 times than undoped activated carbon. The primary product of the desulfurization process was elemental sulfur (74.08%), with sulfuric acid and sulfonic acid as the subsequent by-products. After nitrogen doping, the contents of elemental sulfur and sulfuric acid increased by 5.65 and 1.73 times, respectively. The results revealed the correlations between nitrogen species in hydrothermal aqueous and the desulfurization performance of activated carbon, which could guide the selection of nitrogen-rich aqueous for synthesizing H2S removal N-doped activated carbon via the above novel method.

Highly Dispersed FeAg-MCM41 Catalyst for Medium-Temperature Hydrogen Sulfide Oxidation in Coke Oven Gas.

The traditional hydrolysis-cooling-adsorption process for coke oven gas (COG) desulfurization urgently needs to be improved because of its complex nature and high energy consumption. One promising alternative for replacing the last two steps is selective catalytic oxidation. However, most catalysts used in selective catalytic oxidation require a high temperature to achieve effective desulfurization. Herein, a robust 30Fe-MCM41 catalyst is developed for direct desulfurization at medium temperatures after hydrolysis. This catalyst exhibits excellent stability for over 300 h and a high breakthrough sulfur capacity (2327.6 mgS gcat-1). Introducing Ag into the 30Fe-MCM41 (30Fe5Ag-MCM41) catalyst further enhances the H2S removal efficiency and sulfur selectivity at 120 °C. Its outstanding performance can be attributed to the synergistic effect of Fe-Ag clusters. During H2S selective oxidation, Fe serves as the active site for H2S adsorption and dissociation, while Ag functions as the catalyst promoter, increasing Fe dispersion, reducing the oxidation capacity of the catalyst, improving the desorption capacity of sulfur, and facilitating the reaction between active oxygen species and [HS]. This process provides a potential route for enhancing COG desulfurization.

Study on desulfurization performance of Cu modified red mud-fly ash sorbent

In this paper, fly ash, red mud and Cu(NO3)2·3H2O were used to prepare Cu modified red mud-fly ash sorbent (CuRMFA) by hydration impregnation method, and the sorbent was used to remove SO2 from coal-fired flue gas. The effects of Cu loading and removal conditions (temperature, O2 concentration and NO concentration) on the desulfurization ability of sorbent were studied. The desulfurization performance and mechanism of CuRMFA were analyzed by experimental results and characterizations. The experimental results show that the sorbent CuRMFA can meet the ultra-low emission standard of SO2, and the optimal load of Cu is 20 mg/g. The optimal removal conditions were 500 ℃, 5% O2, 50 mg/m3 NO and 500 mg/m3 SO2, and when the desulfurization efficiency was greater than 93%, the breakthrough time and sulfur capacity were 65.5 min and 230.88 mg/g, respectively. The CuRMFA mainly removes SO2 by chemical reaction, and the desulfurized product exists in the form of SO42-. The conversion of Cu+ to Cu2+ can enhance the electron transfer, enhance the adsorption oxygen conversion and catalytic oxidation performance, which plays an important role in improving the desulfurization performance of the CuRMFA. That Cu modified RMFA is beneficial to form active component 2MgO·SiO2 and decompose of (CaO)12·(Al2O3)7, and can promote the uniform dispersion of active component, which is conducive to reducing the activation energy of desulfurization reaction and speeding up the reaction process.

Sulfidation performance of unsupported and SBA 15-supported Ca-based mixed metal oxides

Coal is the most widely used fossil fuel resource, and clean coal technologies allow an increase in the efficiency of clean energy production. Gasification-based combined cycle power generation systems, for example, aim to produce a mixture of CO and H2 (syngas) formed from coal and biomass. However, H2S is an undesired gasification product of fossil fuels with their high sulfur content. Hot gas desulfurization (HGD) reduces the sulfur contents of the gasification products by eliminating thermal losses of endothermic syngas formation processes. This study aims to develop efficient sorbents to remove H2S from hot flue gas. Unsupported and SBA 15-supported Ca-based binary mixed metal oxides (CuO, FeO, MnO, ZnO) were synthesized as sulfur sorbents by the wet impregnation method. The crystal structure of the sorbents was determined by X-ray diffraction (XRD), while BET analysis was used to determine the surface area and pore size distribution of the sorbents. The results of the XRD and BET analyses revealed mixed metal oxide formation and a high surface area of SBA 15-supported sorbents, respectively. Mixed metal oxide formation was also confirmed by Fourier transform infrared radiation (FTIR) spectroscopy. The desulfurization performance of the sorbents was examined by a simulated gas mixture at 800 °C. A gas chromatography analyzer equipped with a flame photometric detector was used to follow the H2S concentration. SBA 15-supported CaO–MnO exhibited the best desulfurization performance at 800 °C with a breakthrough sulfur capacity (BSC) of 43.38 g S/100 g sorbent in the longest breakthrough time of 1077 min.

Controllable fabrication of persimmon wood-inspired macroporous (a%Co-Mn)1.5Al0.5Ox, high desulfurization performance and analysis of deactivation kinetic mechanism

The removal of H2S that seriously threaten the environment and human health is of great significance in enhancing coal cleaning utilization. Herein, a series of persimmon wood-inspired macroporous (a%Co-Mn)1.5Al0.5Ox (a = 0, 3, 6, 10, 15, 20) sorbents were constructed by the self-assembly of vacuum-assisted sol–gel procedure, and their desulfurization efficiency was evaluated on a fixed-bed reactor at 600–800 °C. Among cobalt-doping sorbents, the breakthrough sulfur capacity (BSC, 272.2 mg g−1) and effective utilization (EU, 81.5%) over (15%Co-Mn)1.5Al0.5Ox is greatly high than the value (138.08 mg g−1) over ZnCoO4/SAPO-34@SBA-15, and slightly lower than BSC (286.2 mg g−1) and EU (92.3%). The magnification SEM images of (15%Co-Mn)1.5Al0.5Ox revealed that regularly straight macroporous channel structure inherited from persimmon wood effectively promoted the rapid diffusion of H2S molecules and accelerated the rate of sulfur/oxygen exchange on the interface of the channel wall. In the meantime, the results studied by the deactivation kinetics model also confirm invariable rate constants (ka, kd) with high correlation coefficients due to higher stability and renewable ability of (15%Co-Mn)1.5Al0.5Ox.

Removal of H2S from simulated blast furnace gas by adsorption over metal-modified 13X zeolite

With the promulgation of new regulations, it’s of great significance to desulfurization from blast furnace gas (BFG) to meet the clean production of iron making industry. Among different desulfurization technologies, zeolite-based sorbents are extensively studied due to the easy operation, low operating cost, and long service life. In this research, the 13X zeolite was selected, and it was ion-exchanged by different metal elements (Cu, Zn, Co, Mn) to prepared a series of sorbents. A fixed bed was used to evaluate their desulfurization behavior, and the XRD, SEM, ICP-OES, XPS, N2 adsorption, and CO2-TPD were carried out to characterize the physical and chemical properties of sorbents. The effects of water vapor content and desulfurization temperature on the removal of H2S were investigated. The regeneration performance of sorbent was also explored. The results showed that the Cu25X-Ex sorbent has the highest breakthrough sulfur capacity of 7.71 g S/100 g sorbent in dry simulated BFG. The breakthrough sulfur capacity of Cu25X-Ex was 4.52 g S/100 g sorbent when the water vapor content is 5 %. The CO2-TPD results showed that the basic sites were favorable for the adsorption of H2S on the surface of zeolite. The XPS results illustrate that the forms of S adsorbed on Cu25X-Ex sorbent were CuS, CuS2O3, and CuSO4, so it is suggested that the reaction between adsorbed H2S with the metal cations in sorbent occurred subsequently. The research indicated that Cu25X-Ex sorbent has potential applicability in the desulfurization of blast furnace gas.

A strategy of KIT-6-carrier modification towards enhancement of desulfurization properties of mesoporous Zn-based sorbents for H2S removal from hot coal gas

Modification of KIT-6 by Ti/W doping (with one-pot synthesis method) was proposed for improving desulfurization performance of ZnO-KIT-6 sorbent. The characterization results indicate that the dopant atoms are present in the form of Ti4+ and W6+, the ordered mesoporous structure of KIT-6 can be retained at Me/Si doping ratios of 1/50–1/20. The presence of [TiO4]4− units in Ti-doped carriers demonstrates that a part of Ti atoms incorporates into the silica framework. Furthermore, moderate Ti doping causes more porous KIT-6 but W doping results in the decline in the specific surface area. Metal doping of Ti/W both show the effects of pore expansion as well as improvement of ZnO-dispersion, favorable for the sulfidation reaction. Generally, the desulfurization properties of sorbents are greatly enhanced by carrier modification. The highest breakthrough sulfur capacity of sorbents containing Ti or W doped KIT-6 are approximate (7.07 and 7.14 g S/100 g sorbent for Ti and W doping, respectively). However, W modification results in greater decrease in orderness of carriers. Additionally, sorbent with Ti-doped carriers has more stable H2S-uptake capacity during five successive sulfidation/regeneration cycles, showing great potential for industrial applications.

Insights to the microwave effect in formation and performance promotion of iron-based carbon nanofibrous composites for H2S removal

Iron-based carbon nanofibrous composites were synthesized as high-temperature coal gas desulfurization sorbents by electrospinning, pre-oxidation and conventional/microwave carbonizations. Compared with conventional method, microwave carbonization effectively promoted the nucleation and growth of zero-valent iron (ZVI) among nanofibers, which in turn expedited the carbonization process of carbon matrix via the catalytic graphitization. Desulfurization performance evaluations showed that the sorbent carbonized by microwave at 700 °C possessed the highest breakthrough sulfur capacity (3.81 g S 100 g−1 sorbent), which might be attributed to the porous structure and rich content of iron species on the surface of nanofibers. The local high temperature induced by the interaction of microwaves and ZVI imparted the sorbent with porous microstructure. In addition, the rapid and high-temperature carbonization of microwave greatly enhanced the diffusion of Fe to the fiber surface due to the difference in thermal expansion coefficients of Fe and carbon. As a consequence, microwave carbonization involves the advantages of high energy efficiency and structural strengthening effect, suggesting its potential for the preparation of desulfurization sorbent.

Functionalization of activated carbon fiber mat with bimetallic active sites for NH3 and H2S adsorption at room temperature

Simultaneous removal of NH3 and H2S at room temperature is of paramount significance for industrial production safety and environmental protection, which has received considerable attention recently. However, single metal compound modification is difficult to achieve highly efficient co-removal performance for NH3 and H2S. Herein, a series of adsorbents with metal chlorides and metal oxides simultaneously loaded in the activated carbon fiber mat were prepared and applied to the NH3 and H2S removal with high efficiency at room temperature. The obtained ACF-NiCl2-MgO possesses large surface area, hierarchical porous structure, as well as uniform dispersion of bimetallic active sites. The advanced porous architecture helps to ensure consistent dispersion of metallic active sites remaining residual channel for the capture of gas molecules. The metal salts facilitate the deamination ability by complexation with NH3, while metal oxides promote the desulfurization ability by chemical adsorption of H2S. The incorporation of metal chlorides and metal oxides significantly improves the adsorption performance of NH3 and H2S. Consequently, the NH3 adsorption capacity of ACF-NiCl2-MgO achieves 22.5 mg NH3/g, and the breakthrough sulfur capacity is as high as 209.2 mg H2S/g. This work provides a new method to design high-capacity binary metal compounds modified activated carbon-based adsorbents for the co-removal of NH3 and H2S at room temperature.

Insights into H2S-absorption and oxidation-regeneration behavior of Ni-doped ZnO-based sorbents supported on SBA-15 for desulfurization of hot coal gas

Sulfur removal from hot coal gas is one of important technologies for highly efficient coal-based energy system. H2S-absorption and oxidation-regeneration behavior of Ni-doped ZnO-based sorbents supported on SBA-15 (ZnNi/SBA-15) was analyzed in this work. The results indicate that ZnNi/SBA-15 shows highest H2S-uptake capacity (16 g S/100 g sorbent) and lowest amount of produced COS (0.0004 g COS/100 g sorbent) when used for desulfurization at 500 °C. Removal of H2S at 700 °C leads to lowest breakthrough sulfur capacity of sorbents. It is ascribed to the destruction of typical microscopic morphology of SBA-15. Boltzmann function is suitable for modeling the H2S-absorption behavior of ZnNi/SBA-15. The evolution rate of H2S for sorbents varies from 0.096 to 0.228 min−1 at 400–700 °C. H2S-CO and H2S-CO2 reactions both contribute to the formation of COS at the stage of H2S-absorption saraturation. Increase of temperature from 550 to 600 °C results in the disappearance of ZnS in regenerated ZnNi/SBA-15. Moreover, most of plugged pore structure caused by sulfidation reaction could restore after regeneration at 600 °C. Further increase of regeneration temperature causes the decline of regeneration efficiency and less porous sorbent. Additionally, the sorbents have stable desulfurization ability and low COS emission during multiple sulfidation-regeneration cycles.

Performance on desulfurization and denitrification of one-step produced activated carbon for purification of sintering flue gas

An innovative one-step process for activated carbon production from low-rank coal is proposed in this research by applying oxidized pellets as activator. The new process can realize synchronous production of the activated carbon and direct reduction iron through combination of carbonization and activation of low-rank coal in one step while no solid wastes were discharged. The desulfurization and denitrification performance of the obtained activated carbon was also evaluated on the simulative sintering flue gas in comparison with one type of commercial activated carbon. The results indicated that a superior activated carbon with high specific surface area of 370.42 m2 g−1, iodine sorption value of 695.13 mg g−1, compressive strength of 315 N·per−1and abrasive resistance of 96.61%, can be prepared under suitable conditions of activation temperature at 850 °C for 140 min with C/Fe mass ratio of 2.5. Meanwhile, the direct reduction iron has a metallization ratio of 88.31%. The activated carbon has a preferable desulfurization performance with the breakthrough sulfur capacity of 5.463 mg/g and breakthrough time of 46.33 min, and single denitrification performance with the breakthrough nitric capacity of 1.935 mg/g and breakthrough time of 90.17 min at flue gas temperature of 80 °C, airspeed ratio of 8370 h−1, gas flow of 1.8 m3/h, and oxygen concentration of 16%. The denitrification of activated carbon in the simultaneous desulfurization and denitrification process can be improved by catalytic reduction via the transformation from NO to N2. The good results show that this process has a bright future with high technical and economic feasibility.

H2O2-assisted self-template synthesis of N-doped biochar with interconnected mesopore for efficient H2S removal

N-doped mesoporous carbon has been used as an efficient metal-free catalyst for hydrogen sulfide (H2S) removal. Traditional synthesis methods for mesopore usually are expensive, corrosive, not eco-friendly, and less N-functional groups remained, leading to the poor removal efficiency for H2S. This study provides a facile and green synthesis of N-doped interconnected mesoporous biochars (HNBCs) designed from waste biomass with the cross-linked lignin self-template removed by H2O2. Compared with those without H2O2 (NPC), HNBCs exhibited higher mesopores volume and more basic sites, i.e., pyridinic N (PdN), pyrrolic N (PyN), -CO, and π-π*, which worked as the main active sites. As a result, adding H2O2 increased the breakthrough sulfur capacity to 181 mg/g for HNBC prepared from cypress sawdust, which was about 5 times that without H2O2 (37 mg/g). The desulfurization and regeneration performance were highly related to the cross-linked mesoporous structure and basic sites on the HNBC. This self-template removing method could easily extend to other waste biomass containing lignin and provide an insight into the advantages of efficient biomass self-structure utilization in the biochar designed properly.

Synthesis of Hydroxyapatite/Zinc Oxide Nanoparticles from Fish Scales for the Removal of Hydrogen Sulfide

The presence of hydrogen sulfide (H2S) is an issue for industrial processing, such as gasoline, natural gas, and biogas. In this study, hydroxyapatite (HA) nanoparticles with high purity were successfully extracted from red tilapia fish scales and used as supporting materials for zinc oxide (ZnO) to remove H2S. Various amounts of ZnO decorated on HA nanoparticles were prepared from a zinc nitrate hexahydrate precursor. Powder X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) of the ZnO/HA samples demonstrated the successful synthesis of ZnO/HA with high purity. The scanning electron microscope (SEM) image analysis confirmed the uniform deposition of ZnO on HA nanoparticles which were smaller than 245 nm. The ZnO/HA samples with different ZnO loadings (i.e., 5, 10, and 15 wt%) were used to remove H2S at room temperature. The specific surface area of HA and ZnO/HA determined by the Brunauer-Emmett-Teller (BET) method was 37.022 (m2/g) and 111.609 (m2/g), respectively. The experimental results demonstrated the highest breakthrough sulfur capacity of 26.3 mg S/g with the sorbent ZnO (15 wt%)/HA nanoparticles. This H2S adsorption capacity was the highest capacity ever achieved for ZnO/HA.Therefore, there are great possibilities for effective removal of H2S at the ambient conditions using the ZnO (15 wt%)/HA nanoparticles, where HA nanoparticles could be sustainably extracted from the abundant organic source of red tilapia fish scales.