选择性离子吸附原理与材料制备

制备特定无机阴、阳离子的选择性吸附材料有利于保障饮用水安全、控制外排污水生态风险、保障地表水环境质量,具有非常广泛的市场需求和应用前景。选择性离子吸附材料研发始于20世纪60年代,经过60年的高速发展,选择性离子吸附材料领域目前依旧保持了极高的研究热度和研究水平。本文概述了选择性离子吸附材料的研发历史、现状和主要研究方向,重点总结了四种选择性离子吸附原理(即分子印迹技术原理、软硬酸碱理论、非静电作用原理和竞争离子自我抑制原理)和它们的研究历史、选择性离子吸附材料制备与应用情况,展望了未来的研究方向,这些信息的整理归纳将为未来的选择性离子吸附材料研发、水中特定离子浓度控制提供重要的借鉴。

负离子—选择性吸附材料的功能与低碳理念

本文阐述了负离子—选择性吸附材料释放负氧离子和选择性吸附有害气体的原理,介绍了其作为室内空气净化材料的应用方式,并从无源释放负氧离子节能、直接吸收二氧化碳气体和复合制备绿色建筑材料等角度论证了负离子—选择性吸附材料的低碳生活理念。

离子液体在无机合成中的应用

本文介绍了离子液体在无机合成中的应用。简要讨论了离子液体作为模板剂、溶剂和前驱体在合成中的主要作用,还简要介绍了离子液体与目标产物表面的相互作用类型及在“几何匹配原理”指导下离子液体的选择性吸附。

Synergistic interaction of Nb atoms anchored on g‐C_(3)N_(4) and H^(+) promoting high‐efficiency nitrogen reduction reaction

Nowadays catalytic nitrogen reduction reaction(NRR)by electrochemistry has attracted much attention because of its key role in producing the basic chemical product ammonia with low energy consumption.A stable and environmentally‐friendly single‐or multi‐atom catalyst with good performance in activity and selectivity is highly desired for NRR.From density functional theory calculations,the NRR mechanisms catalyzed by Nb monomer,dimer,trimer and tetramer anchored on graphitic carbon nitride(Nb_(x)@g‐C_(3)N_(4),x=1,2,3,4)have been deeply explored.It has been found that Nb_(3)@g‐C_(3)N_(4) exhibits the best catalytic ability among the four catalysts with the introduction of H+.A more stable intermediate(*NH_(2)+*H)can be found to reduce the huge free energy barrier of forming*NH_(3) from*NH_(2) directly in a multi‐atom system.By analyzing the density of states and projected crystal orbital Hamilton population,a synergistic effect among Nb atoms and the adsorbed H^(+)is responsible for reducing the overpotential of NRR.Furthermore,the competitive hydrogen evolution reaction is suppressed effectively.This work introduces a new insight in the reaction pathway in multi‐atoms for developing high‐efficiency NRR catalysts.

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.

An advanced partitioning process for key elements separation from high level liquid waste

To separate MA （Am, Cm） and some fission product elements （FPs） such as Tc, Pd, Cs and Sr from high level liquid waste （HLLW） systematically, we have been studying an advanced aqueous partitioning process, which uses selective adsorption as the separation method. For this process, we prepared several novel adsorbents which were immobilized in a porous sili- c^polymer composite support （SiO2-P）. Adsorption and separation behavior of various elements was studied experimentally in detail. Small scale separation tests using simulated HLLW solutions were carried out. Pd（II） was strongly adsorbed by the AR-01 anion exchanger and effectively eluted off by using thiourea. Successful separation of Pd（ll） from simulated HLLW was achieved. Te（VII） also exhibited strong adsorption on AR-01 and could be eluted off by using U（IV） as a reductive eluent. Am（Ⅲ） presented significantly high adsorbability and selectivity onto R-BTP/SiOz-P adsorbents over various FPs including Ln（Ⅲ）. The R-BTP adsorbents were fairly stable in 3 M HNO3, but instable against 7-irradiation-3M HNO3. An advanced par- titioning process consisting of three separation columns for the target elements separation from HLLW was proposed and the obtained experiment results indicated that the proposed process is essentially feasible.

Pyridinium salt-based covalent organic framework with well-defined nanochannels for efficient and selective capture of aqueous^(99)TcO_(4)^(-)

Ionic covalent organic framework(COF)materials with high specific surface areas and well-defined pore structures are desired for many applications yet seldom reported.Herein,we report a cationic pyridinium salt-based COF(PS-COF-1)with a Brunauer-Emmett-Teller(BET)surface area of 2703 m^(2) g^(-1),state-ofthe-art for an ionic COF.Aided by its ordered pore structure,chemical stability,and radiation resistance,PS-COF-1 showed exceptional adsorption properties toward aqueous ReO_(4)^(-)(1262 mg g^(-1))and ^(99)TcO_(4)^(-).Its adsorption performance surpassed its corresponding amorphous analogue.Importantly,PS-COF-1 exhibited fast adsorption kinetics,high adsorption capacities,and selectivity for ^(99)TcO_(4)^(-)and ReO_(4)^(-)at high ionic strengths,leading to the successful removal of ^(99)TcO_(4)^(-)under conditions relevant to low-activity waste streams at US legacy Hanford nuclear sites.In addition,PS-COF-1 can rapidly decontaminate ReO_(4)^(-)/^(99)TcO_(4)^(-)polluted potable water(~10 ppb)to drinking water level(0 ppb,part per billion)within 10 min.Density functional theory(DFT)calculations revealed PS-COF-1 has a strong affinity for ReO_(4)^(-)and ^(99)TcO_(4)^(-),thereby favoring adsorption of these low charge density anions over other common anions(e.g.,Cl^(-),NO_(3)^(-),SO_(4)^(2-),CO_(3)^(2-)).Our work demonstrates a novel cationic COF sorbent for selective radionuclide capture and legacy nuclear waste management.

Selective adsorption and stable solidification of radioactive cesium ions by porous silica gels loaded with insoluble ferrocyanides

Development of highly functional cesium selective adsorbents for the decontamination of high-activity-level water(HALW) from the Fukushima NPP-1 accident is very urgent. In order to selectively adsorb the radioactive cesium, three kinds of novel porous silica gels loaded with insoluble ferrocyanides(SLFC) were prepared using a successive impregnation/precipitation method. Based on the results of previous research, the SLFC composites have relatively large uptake ratio above 95%, distribution coefficients(Kd) above 103 cm3/g, and excellent adsorption kinetics even in seawater. The solidification results also indicate that zeolites have an excellent Cs immobilization characteristic, gas-trapping and self-sintering abilities, and low leachability. We chose three kinds of SLFC composites to achieve the optimization of solidification by mixing with nine kinds of additives at high temperatures(up to 1200 °C). The Cs contents in the three composites were estimated to be below 30% of the initial contents and decreased with the three stages at calcination temperatures ranging from 25 to 1200 °C. By contrast, the Cs immobilization ratio was markedly lowered by mixing with additives: of those, allophane had the best immobilization result. By increasing the additive ratio to 50 wt%, the Cs immobilization ratio became almost 100% and no volatilization of Cs was detected even after calcination at 1200 °C. This result indicates that calcination of the mixture of SLFC composites after adsorbing Cs+ ions and specific additives under appropriate ratio is effective for stable solidification.