Effect of Elastic Strains on Adsorption Energies of C,H and O on Transition Metal Oxides

Platinum(Pt)-based noble metal catalysts(PGMs)are the most widely used commercial catalysts,but they have the problems of high cost,low reserves,and susceptibility to small-molecule toxicity.Transition metal oxides(TMOs)are regarded as potential substitutes for PGMs because of their stability in oxidizing environments and excellent catalytic performance.In this study,comprehensive investigation into the influence of elastic strains on the adsorption energies of carbon(C),hydrogen(H)and oxygen(O)on TMOs was conducted.Based on density functional theory(DFT)calculations,these effects in both tetragonal structures(PtO_(2),PdO_(2))and hexagonal structures(ZnO,CdO),along with their respective transition metals were systematically explored.It was identified that the optimal adsorption sites on metal oxides pinpointed the top of oxygen or the top of metal atom,while face-centered cubic(FCC)and hexagonal close-packed(HCP)holes were preferred for the transition metals.Furthermore,under the influence of elastic strains,the results demonstrated significant disparities in the adsorption energies of H and O between oxides and transition metals.Despite these differences,the effect of elastic strains on the adsorption energies of C,H and O on TMOs mirrored those on transition metals:adsorption energies increased under compressive strains,indicating weaker adsorption,and decreased under tension strains,indicating stronger adsorption.This behavior was rationalized based on the d-band model for adsorption atop a metallic atom or the p-band model for adsorption atop an oxygen atom.Consequently,elastic strains present a promising avenue for tailoring the catalytic properties of TMOs.

阴离子捕获剂及其在污染防治与环境修复领域中的应用

综述了阴离子捕获剂的结构、性能、制备与表征方法、吸附专属性及其在环境修复方面的应用。阴离子捕获剂是一种具有层状结构的阴离子粘土,由于其特殊的结构和性能,可通过层间阴离子交换、层状结构重建等机制来吸附环境中的阴离子,从而清除环境中的污染物。大量研究表明,阴离子捕获剂对环境中以络阴离子形式存在的重金属污染物有很强的吸附能力,并能有效吸附水体中的N、P、As、Se和放射性元素。此外,阴离子捕获剂还能吸附有机污染物,如农药、酚类化合物、洗涤剂和腐殖质等。从环境中除去不同类型的有毒有害组分,需使用不同类型的阴离子捕获剂。其吸附能力主要由捕获剂本身的特点和外部理化条件所决定。阴离子捕获剂的研究已成为当前环境保护工程和技术研究的一个新热点。

Adsorption of Cu^(2+) from aqueous solution by modified biomass material

Cu2+ adsorption from simulated aqueous solution was investigated using a modified spent shiitake substrate (MSSS). The results showed that the MSSS has a high adsorption efficiency and removal performance. The Cu2+removal rate of the MSSS reached above 95%. Compared with spent shiitake substrate (SSS), the specific surface area, electronegativity and surface functional groups of the MSSS were all improved, resulting in a high adsorption capacity. The Cu2+ adsorption of MSSS reached equilibrium after 0.75 h and was an exothermic reaction. The SEM and EDS analyses of the MSSS before and after Cu2+ adsorption showed that the pores on the surface of the MSSS were occupied after adsorption and the Cu content increased but the Na content decreased.

Competitive adsorption of heavy metal ions on peat

The uptake capacities, and the adsorption kinetics, of copper, Cu（Ⅱ）, nickel, Ni（Ⅱ）, and cadmium, Cd（Ⅱ）, on peat have been studied under static conditions. The results show that the adsorption rates are rapid： equilibrium is reached in twenty minutes. The adsorption of copper, nickel and cadmium is pH dependent over the pH range from 2 to 6. The adsorption kinetics can be excellently described by the Elovich kinetic equation. The adsorption isotherm fits a Langmuir model very well. The adsorption capacities follow the order Cu^2＋ 〉 Ni^2＋〉 Cd^2＋ in single-component systems and the competitive adsorption capacities fall in the decreasing order Cu^2＋ 〉 Ni^2＋〉 Cd^2＋ in multi-component systems. The adsorption capacities of these three heavy metal ions on peat are consistent with their observed competitive adsorption capacities.

Effect of Carrier Processing Temperature on Its Properties for Adsorption of Active Metals

The influence of the carrier pseudo-boehmite （PB）, which was impregnated with a Ni-Mo-P solution under over- saturation conditions and treated at different temperatures, on its property for adsorption of active metals （Ni, Mo） was studied. The results showed that the amount for adsorption of active metal was decreased with an increasing treatment tem- perature of the carrier. After phase transition of the carrier PB to γ-Al2O3, its capacity for adsorption of active metals was significantly reduced. The difference in properties for adsorption of active metals （Ni, Mo） by PB dried at 120℃ and γ-Al2O3 calcined at 600℃ was studied in detail. The results suggested that the ability of the PB carrier to adsorb metals was higher than that of theγ-Al2O3 carrier. Especially, the ratio of chemically adsorbed metals on the PB support was much higher than 3＇-alumina. The chemical adsorption sites on the PB carrier were proved to be much more than those on the γ-Al2O3 carrier. Ni and Mo chemical adsorption sites differed a lot on the carrier possibly because of the difference in chemical adsorption sites.

Adsorption of Heavy Metal Ions by Adsorbent from Waste Mycelium Chitin

The adsorption properties of chitin adsorbent from mycelium of fermentation industries for the removal of heavy metal ions were studied. The result shows that the chitin adsorbent has high adsorption capacity for many heavy metal ions and Ni2+ in citric acid. The influence of pH was significant:When pH is higher than 4.0, the high adsorption capacity is obtained,otherwise H+ ion inhibits the adsorption of heavy metal ions. The comparison of the chitin adsorbent with some other commercial adsorbents was made, in which that the adsorption behaviorchitin adsorbent is close to that of commercial cation exchange adsorbents, and its cost is much lower than those commercial adsorbents.

Synthesis of magnetically modified palygorskite composite for immobilization of Candida sp. 99–125 lipase via adsorption

Magnetically modified palygorskite composites were synthesized with γ-Fe2O3 dispersing on the external surface of clay mineral. The magnetic clay was characterized with Fourier transform infrared, X-ray diffrac- tion, transmission electron microscopy, and vibrating sample magnetometer. Candida sp. 99-125 lipase was immobilized on magnetic palygorskite composites by physical adsorption with enzyme loading of 41.5 mg· g^-1 support and enzyme activity of 2631.6 U· （g support）^-1. The immobilized lipase exhibit better thermal and broader pH stability and excellent reusabilitV compared with free lipase.

Heavy metals adsorption by banana peels micro-powder: Equilibrium modeling by non-linear models

In this study the copper and lead adsorption efficiency onto banana peels powder was investigated. The agroindustrial waste recovery represents one of the Circular Economy pillars. In the view of the synthesis of an environmentally friendly adsorbent material, the powder was used without any preliminary chemical or thermal activation, but only after simple washing, drying and grinding. The bio-adsorbent was characterized by the FTIR technique and tested in batch mode on synthetic aqueous solutions containing Pb and Cu in the range 10–90 mg·L^(-1). A selection of two(Langmuir, Freundlich) and three(Sips, Redlich–Peterson, Koble–Corrigan) parameter isotherm models was chosen to fit adsorption equilibrium data by non-linear regression procedure. The best fit isotherm model was selected relying on the error function with the lowest average percentage error(APE) value, among those characterized by the highest R^2 values. As expected, the three-parameter models are found to better represent both metals bio-adsorption, with APE and R^2 values always lower and higher, respectively, than the corresponding values obtained for the two-parameter models.

Heterogeneity of Adsorption Sites and Adsorption Kinetics of n-Hexane on Metal–Organic Framework MIL-101(Cr)

The heterogeneity of adsorption sites and adsorption kinetics of n-hexane on a chromium terephthalate-based metal-organic framework MIL-10^1 （Cr） were studied by gravimetric method and temperature-programmed desorption （TPD） experiments. The MIL-101 crystals were synthesized by microwave irradiation method. The ad- sorption isotherms and kinetic curves of n-hexane on the MIL-101 were measured. Desorption activation energies of n-hexane from the MIL-10^1 were estimated by TPD experiments. The resulthowed that equilibrium amount ofn-hexane adsorbed on the MIL-10^1 was up to 5.62 mmol.g- 1 at 298 K and 1.6 x10^4 Pa, much higher than that of some activated carbons, zeolltes and so on. The isotherms of n-hexane on the MIL-101 could be well fitted with Langmuir-Freundlich model. TPD spectra exhibit two types of adsorption sites on the MIL-101 with desorption activation energies of 39.41 and 86.69 kJ. mol-1. It reflects the surface energy heterogeneity on the MIL-10I frameworks for n-hexane adsorption. The diffusion coefficients of n-hexane are in the range of （1.35- 2.35 ） x 10 - 1 o cm2. s - 1 with ad sorotion activation enerv of 16.33 kl. mol - 1.

Biosorption of Toxic Zn（ll） Ion from Water Using Ion Imprinted Interpenetrating Polymer Networks

Toxic Zn（II） ion imprinted interpenetrating polymer networks were synthesized for the selective sorption of Zn（ll） from aqueous solutions using a biopolymer alginic acid. The polymeric biosorbant was prepared using Zn（II） ion as template, acrylamide as functional monomer, cross linker NNMBA （N,N＇ Methylene-bis-acrylamide） and potassium persulphate as an initiator. The non-imprinted polymer networks were also prepared without use of the Zn（II） ion. The synthesized interpenetrating networks were characterized by various spectral techniques. Metal ion binding studies were carried out and the factors affecting binding were also optimized. Competitive sorption studies were investigated to determine the selectivity of Zn（II） ion imprinted interpenetrating polymer network. Zinc ion imprinted polymer networks showed good selectivity for the target ion.

经典等温吸附模型在重金属离子/硅藻土体系中的应用及存在问题

为了深入了解天然硅藻土对常见重金属离子Cu2+、Zn2+、Pb2+、Cd2+、Mn2+、Fe3+的吸附属性,同时也为了发现经典等温吸附模型应用于液/固体系时存在的问题,开展了系列等温吸附研究.结果表明,最适于描述天然硅藻土对Pb2+、Cd2+、Cu2+、Zn2+、Mn2+、Fe3+吸附的模型分别为Tenkin、Tenkin、Langmuir、Tenkin、Freundlich和Freundlich模型.各离子在天然硅藻土上的吸附以物理过程为主,吸附反应容易进行.液/固体系中,应用经典等温吸附模型对试验数据进行线性拟合时,发现平衡吸附量q e不是离子平衡浓度c e的唯一函数,而是c e与吸附剂浓度W0两个变量的函数,q e与c e/W0具有一一对应的函数关系.经典等温吸附模型存在明显的吸附剂浓度效应,参数值不稳定,模拟值与实测值差异显著,缺乏实际指导意义.试验证明新的四组分模型可用于描述天然硅藻土-水溶液体系中单一离子的吸附行为,新模型参数k与q m值也具有唯一性,可用于给定体系的实际定量计算.

Passively mode-locked Er-doped fiber laser based on SnS2 nanosheets as a saturable absorber

In this paper, tin disulfide （SnS2）, a two-dimensional （2D） n-type direct bandgap layered metal dichalcogenide with a gap value of 2.24 eV, was employed as a saturable absorber. Its appearance and nonlinear saturable ab- sorption characteristics were also investigated experimentally. SnSz-PVA （polyvinyl alcohol） film was successfully prepared and employed as a mode-locker for achieving a mode-locked Er-doped fiber laser with a pulse width of 623 fs at a pulse repetition rate of 29.33 MHz. The results prove that SnS2 nanosheets will have wide potential ultrafast photonic applications due to their suitable bandgap value and excellent nonlinear saturable absorption characteristics.

Flexible 3D porous metal-organic framework exhibiting selective adsorption for H_2O over organic solvents

A new flexible 3D porous metal-organic framework （MOF） with 1D open nanotube, [Co2（/zs-CTAl）（dpe）（H20）2]n-6n（H20） （1） （CTA = cyclohexane-1,2,4,5-tetracarboxylic acid, dpe = 1,2-di（4-pyridyl） ethylene） has been prepared and structurally character- ized. Meanwhile, each 1D nanotubes filled with 1D water chain with dimension of 13.711 ~ 12.275/~2. Compound 1 represents a new example that collapse/deform upon dehydration/hydration and shows adsorb 1-120 selectively over organic solvents.

A microporous lanthanide metal-organic framework containing channels:Synthesis,structure,gas adsorption and magnetic properties

Under solvothermal condition,the reaction of furan-2,5-dicaboxylate(H2FDA) and glycol with Gd(NO3)3.6H2O gave microporous lanthanide metal-organic framework(MOF),{[Gd(FDA)1.5(glycol)].1.5H2O}}n(1).This compound was characterized by single crystal X-ray diffraction,infrared spectroscopy,elemental analysis,thermogravimetry analysis,and powder X-ray diffraction.The Gd(III) ions were connected by carboxylic group of FDA2-to give 1D chains,which were further linked by FDA2-,forming a 3D porous framework with 3D channels.Gas adsorption properties with N2,H2 and CO_(2) of the compound were studied.Magnetic studies show that there are weak ferromagnetic interactions transmitted by μ1,3 carboxylic group between the Gd(III) ions.