Oxidation of emerging organic contaminants by in-situ H_(2)O_(2) fenton system

The existence and risk of emerging organic contaminants(EOCs)have been under consideration and paid much effort to degrade these pollutants.Fenton system is one of the most widely used technologies to solve this problem.The original Fenton system relies on the hydroxyl radicals produced by Fe(Ⅱ)/H_(2)O_(2) to oxidize the organic contaminants.However,the application of the Fenton system is limited by its low iron cycling efficiency and the high risks of hydrogen peroxide transportation and storage.The introduction of external energy(including light and electricity etc.)can effectively promote the Fe(Ⅲ)/Fe(Ⅱ)cycle and the reduction of oxygen to produce hydrogen peroxide in situ.This review introduces three in-situ Fenton systems,which are electro-Fenton,Photo-Fenton,and chemical reaction.The mechanism,influencing factors,and catalysts of these three in-situ Fenton systems in degrading EOCs are discussed systematically.This review strengthens the understanding of Fenton and in-situ Fenton systems in degradation,offering further insight into the real application of the in-situ Fenton system in the removal of EOCs.

In-situ preparation of Cu-BTC modified with organic amines for H_(2)S removal under ambient conditions

Amine modification is an effective strategy to improve the H_(2)S removal performance of Cu-BTC.In order to avoid the problem of pore blockage after amine modification in post synthesis impregnation,herein a series of Cu-BTC modified with organic amine adsorbents were prepared via an in-situ one-pot method and the H_(2)S removal performance under ambient conditions was tested.It is found that the introduced organic amines,depending on the types of amine selected,have a significant influence on the growth of Cu-BTC and its textural properties.The H_(2)S removal performance on the as-prepared materials suggested that the amine modified samples remarkably improved the H_(2)S removal capacities with an order of BA-Cu-BTC>TEA-Cu-BTC>TEOA-Cu-BTC>Cu-BTC.Besides the enlarged surface area and the increased mesopores volumes,BA has the advantages of smaller steric hindrance and-NH_(2)groups,among which the former increased the accessibility of Cu active sites while the latter acted as additional active sites for H_(2)S capturing,thus affording BA-Cu-BTC highest breakthrough capacity of 77.3 mg S/g.Overall,this study elaborates the effect of organic amines in-situ modification on the Cu-BTC structure and desulfurization.

CO_(2)吸附强化CH_(4)/H_(2)O重整制氢催化剂研究进展

CO_2吸附强化CH_4/H_2O重整制氢是提供低成本高纯氢气和实现CO_2减排的方法之一。其中,催化剂和吸附剂是该工艺的重要组成部分,其活性与选择性制约了反应速率和产率,寿命长短关系到生产成本。综述了CO_2吸附强化CH_4/H_2O重整制氢催化剂和吸附剂的研究现状及存在的问题,机械混合的催化剂与吸附剂在反应过程中存在吸附产物包覆催化活性位点的问题,导致催化剂活性迅速下降。针对该问题,进一步探讨了不同结构双功能复合催化剂的结构特性、研究现状及其在循环-再生过程中存在的问题,核壳型双功能催化剂具有吸附组分与催化剂组分相对独立、催化组分分散分布和比表面积大等优点,在吸附强化制氢中有进一步研究的潜力。利用双功能催化剂的结构特点,实现反复循环再生过程中催化与脱碳反应的匹配,是推动CO_2吸附强化CH_4/H_2O重整制氢技术工业化发展的关键。

生物质气化原位吸储氢吸附强化水汽变换制氢

为研究废樟木生物质原料空气气化,通过吸氢材料(Mg_(2)Ni)原位吸储氢WGS(水汽变换)制取纯氢气,通过Aspen Plus搭建生物质气化吸附强化制氢模型,研究温度、空气当量比、Mg_(2)Ni储氢材料用量和蒸汽与碳摩尔比x_(S/C)对原位储氢生物质气化吸附强化水汽变换制氢的影响。结果表明:添加Mg_(2)Ni储氢材料原位吸储氢强化了WGS反应,提高了氢气的产率和一氧化碳转化率,加热Mg_(2)NiH_(4)释放纯氢气;水蒸气含量的增加促进了WGS反应并抑制了甲烷反应;在能量分析中,生成的氢气能量占系统输入总能量的42.7%,为系统输入总[火用]的54.9%,说明通过吸氢材料原位吸附来制取氢气可以获得高质量的氢气,并在加热吸附剂的过程中获得纯氢气。

Localized CdS homojunctions with optimal ratio of high and low index facets to dynamically boost H_(2)O splitting into H_(2)energy

Localized CdS homojunctions with optimal ratio of high and low index facets are constructed to dy-namically boost H_(2)O splitting into H_(2)energy by hydrothermal method in combination with calcination.By density functional theory,hall effect,and in situ diffuse reflectance infrared Fourier transform spec-troscopy,it is revealed that photo-irradiated e^(−)and h^(+)can be spatially separated and directionally trans-ferred to the reductive high-index facet{002}and oxidative low-index facet{110}of localized CdS homo-junction induced by Fermi level difference of both high and low index facets to dehydrogenate ^(∗)-OH and coupled ^(∗)-O intermediates for H_(2)and O_(2)yield,respectively,along with a solar conversion into hydrogen of 1.93%by AM 1.5 G irradiation at 65℃.The study work suggests a scientific perspective on the optimal ratio of high and low index facets to understand photo-generated charge carrier transfer dynamically and their photocatalytic principle for H_(2)O splitting reaction in kinetics.

An in-situ NH_(4)^(+)-etched strategy for anchoring atomic Mo site on ZnIn_(2)S_(4) hierarchical nanotubes for superior hydrogen photocatalysis

Atomic sites co-catalyst (ASC) on photocatalytic materials possesses an attractive prospect to promote charge carrier separation and tune surface reaction kinetics,yet the synthesis of earth-abundant ASC under low temperature remains a great challenge.Here,a novel in-situ NH_(4)^(+)-etched strategy to anchor atomic Mo sites on ZnIn_(2)S_(4)hierarchical nanotubes (HNTs) with abundant mesopores under mild conditions for promoting charge carrier separation and enhancing light multi-reflections is developed for efficient photocatalytic H_(2) evolution.Density functional theory calculations and linear sweep voltammetry demonstrate that the well-defined Mo-S_(2)O_(1) sites with distinctive coordination configuration and electronic property contribute to the enhanced separation of photo-generated charge carriers and reduced Gibbs free energy for H_(2) evolution.Consequently,the well-defined MoSA-ZIS HNTs present an excellent photocatalytic activity with a rate of 29.9μmol h^(-1)(5.98 mmol g^(-1)h^(-1)),which is 7.3 times higher than that of ZnIn_(2)S_(4)nanosheets (NSs),to be among the best ZnIn_(2)S_(4)-based photocatalysts.The present strategy breaks the high-temperature limitation of conventional top-down thermal dissociation/emitting approach for anchoring non-noble metal atomic sites on catalyst support.

Development of an in-situ H_(2)reduction and moderate oxidation method for 3,5-dimethylpyridine hydrogenation in trickle bed reactor

The Ru/C catalyst prepared by impregnation method was used for hydrogenation of 3,5-dimethylpyridine in a trickle bed reactor.Under the same reduction conditions(300°C in H_(2)),the catalytic activity of the non-in-situ reduced Ru/C-n catalyst was higher than that of the in-situ reduced Ru/C-y catalyst.Therefore,an in-situ H_(2)reduction and moderate oxidation method was developed to increase the catalyst activity.Moreover,the influence of oxidation temperature on the developed method was investigated.The catalysts were characterized by Brunauer–Emmett–Teller method,hydrogen temperature programmed reduction H_(2)-TPR,hydrogen temperature-programmed dispersion(H_(2)-TPD),X-ray diffraction,energy dispersive spectroscopy,X-ray photoelectron spectroscopy,Raman spectroscopy,O2 chemisorption and oxygen temperature-programmed dispersion(O2-TPD)analyses.The results showed that there existed an optimal Ru/RuO_(x)ratio for the catalyst,and the highest 3,5-dimethylpyridine conversion was obtained for the Ru/C-i1 catalyst prepared by in-situ H_(2)reduction and moderate oxidation(oxidized at 100°C).Excessive oxidation(200°C)resulted in a significant decrease in the Ru/RuO_(x)ratio of the in-situ H_(2)reduction and moderate oxidized Ru/C-i2 catalyst,the interaction between RuO_(x)species and the support changed,and the hard-to-reduce RuO_(x)species was formed,leading to a significant decrease in catalyst activity.The developed in-situ H_(2)reduction and moderate oxidation method eliminated the step of the non-in-situ reduction of catalyst outside the trickle bed reactor.

Recent advances in H_(2)O_(2)-based advanced oxidation processes for removal of antibiotics from wastewater

As important emerging contaminants, antibiotics have caused potential hazards to the ecological environment and human health due to their extensive production and consumption. Among various techniques for removing antibiotics from wastewater, H_(2)O_(2)-based advanced oxidation processes(AOPs) have received increasing attention due to their fast reaction rate and strong oxidation capability. Hence this review critically discusses:(i) Recent research progress of AOPs with the addition of H_(2)O_(2) for antibiotics removal through different methods of H_(2)O_(2) activation;(ii) recent advances in AOPs that can in-situ generate and activate H_(2)O_(2) for antibiotics removal;(iii) H_(2)O_(2)-based AOPs as a combination with other techniques for the degradation and mineralization of antibiotics in wastewater. Future perspectives about H_(2)O_(2)-based AOPs are also presented to grasp the future research trend in the area.

Comprehensive investigation on robust photocatalytic hydrogen production over C_(3)N_(5)

Carbon nitride has drawn numerous eyes in the past decade,whereas the photocatalytic performance is significantly limited by its wide band-gap(~2.7 e V for C_(3)N_(4))simultaneously.Recently,C_(3)N_(5)with narrower band-gap has been reported,however,a systematically investigation on its photoactivity for H_(2)production has not been reported.The present work demonstrates the synthesis of C_(3)N_(5)by thermal treatment of 3-amino-1,2,4-triazole,and the photocatalytic performance for H_(2)production of C_(3)N_(5)is investigated comprehensively.Photocatalytic H_(2)production rate of C_(3)N_(5)is~2.2 times higher than that of C_(3)N_(4) with 1.0 wt%Pt as co-catalyst,and series of experiments are carried out to explore the behind elements accounting for the high photoactivity.Combining the results of DRS,PL and photocurrent,it is found that C_(3)N_(5)possesses wider visible light absorption region,lower band-gap and quicker photogenerated e^(-)/h^(+)separation efficiency.Moreover,characterizations including in-situ DRIFTS are adopted to monitor the adsorption property of H_(2)O on C_(3)N_(5),which plays a significant role in surface water reduction reaction,and higher amount of adsorbed H_(2)O molecules on C_(3)N_(5)is confirmed.The present work exhibits new insights into the high photocatalytic performance of N-rich carbon nitride catalysts.

In situ grown TiN/N-TiO_(2)composite for enhanced photocatalytic H_(2)evolution activity

Titanium nitride(TiN)decorated N-doped titania(N-TiO_(2))composite(TiN/N-TiO_(2))is fabricated via an in situ nitridation using a hydrothermally synthesized TiO_(2)and melamine(MA)as raw materials.After the optimization of the reaction condition,the resultant TiN/NTiO_(2)composite delivers a hydrogen evolution activity of up to 703μmol/h under the full spectrum irradiation of Xelamp,which is approximately 2.6 and 32.0 times more than that of TiO_(2)and TiN alone,respectively.To explore the underlying photocatalytic mechanism,the crystal phase,morphology,light absorption,energy band structure,element composition,and electrochemical behavior of the composite material are characterized and analyzed.The results indicate that the superior activity is mainly caused by the in situ formation of plasmonic TiN and N-TiO_(2)with intimate interface contact,which not only extends the spectral response range,but also accelerates the transfer and separation of the photoexcited hot charge carrier of TiN.The present study provides a fascinating approach to in situ forming nonmetallic plasmonic material/N-doped TiO_(2)composite photocatalysts for high-efficiency water splitting.

A conformal titanyl phosphate amorphous overlayer for enhancing photoelectrochemical hydrogen peroxide production

Photoelectrochemical(PEC)H_(2)O_(2)production through water oxidation reaction(WOR)is a promising strategy,however,designing highly efficient and selective photoanode materials remains challenging due to competitive reaction pathways.Here,for highly enhanced PEC H_(2)O_(2)production,we present a conformal amorphous titanyl phosphate(a-TP)overlayer on nanoparticulate TiO_(2)surfaces,achieved via lysozyme-molded in-situ surface reforming.The a-TP overlayer modulates surface adsorption energies for reaction intermediates,favoring WOR for H_(2)O_(2)production over the competing O_(2)evolution reaction.Our density functional theory calculations reveal that a-TP/TiO_(2)exhibits a substantial energy uphill for the O·*formation pathway,which disfavors O_(2)evolution but promotes H_(2)O_(2)production.Additionally,the a-TP overlayer strengthens the built-in electric field,resulting in favorable kinetics.Consequently,a-TP/TiO_(2)exhibits 3.7-fold higher Faraday efficiency(FE)of 63%at 1.76 V vs.reversible hydrogen electrode(RHE)under 1 sun illumination,compared to bare TiO_(2)(17%),representing the highest FE among TiO_(2)-based WOR H_(2)O_(2)production systems.Employing the a-TP overlayer constitutes a promising strategy for controlling reaction pathways and achieving efficient solar-to-chemical energy conversion.

PSS sorbents for removing trace hydrogen sulfide in methane

Sorbents of the pressure swing sorption process(PSS)to remove trace amount of H_(2)S(190 ppm)contained in methane were experimentally studied.The sorbents consist of adsorbent carrier(silica gel or activated carbon)and absorbent which spreads outside the carrier granules’pores(triethanolamine,TEA or N-methyl-2-pyrrolidone,NMP).The results of breakthrough and regeneration tests show that silica gel is more suitable to be the carrier than activated carbon and TEA is more suitable to be the absorbent than NMP.The loaded absorbent could enlarge the sorption capacity of H_(2)S considerably.And the BET tests indicate that the absorbent deposits on the surface of the carrier’s pores and can reduce the mesopores’size and block the micropores.