Studies of Adsorption of Cadmium Ions by Biowaste Adsorbent from Aqueous Solutions with Ion-Selective Electrodes and ICP-OES

Using environment-friendly and low-cost biowaste adsorbents as toxic metal ion removal substrates from aqueous solutions has a great economic advantage. This work evaluated pumpkin and potato peel biowastes for the adsorption of cadmium ions. The biowastes were treated with acid or base. Batch experiments were carried out by introducing a known concentration of metal ion solution into the biowaste sorbent at various pH levels. The pH and metal ion concentration was monitored with pH and cadmium ion-selective electrode continuously for two hours, and the final concentration for the metal ion after 24 hours was measured with the cadmium electrode and then confirmed with ICP-OES. L-type isotherms were obtained that fit to Freundlich model. Adsorption isotherms showed chemical adsorption and the kinetics following the second order model. Equilibrium adsorption capacity is higher than 29 mg/g at pH 5.6 when the initial concentration is 220 ppm. Dynamic cadmium adsorption capacity is 17 mg/g from aqueous solution when the feed solution is 220 ppm with pumpkin peel biowaste sorbent. The biowaste materials can be regenerated with acid washing.

Direct Determination of Potassium-Sodium Activity Ratio in Soil Suspension with Two Ion-Selective Electrodes

A K^+-selective electrode and a Na^+-selective electrode were used to construct a measuring cell without liquid-junction for the determination of the ion activity ratio of K^+ to Na^+ in soil suspensions.The measured cell potential was not affected by the total electrolyte concentration when the total cation concentration was 10^-1-10^-3 mol L^-1 and the concentration ratio Ck+/CNa+ was 10:1 to 1:50.When the concentration ratios were equal to 1 and the total electrolyte concentrations were 10^-2 and 10^-3 mol L^-1,the ion activity ratio measurenent would not be affected by pH in the pH range of 3.5 to 11.5 and 4.4 to 11 respectively.Ions other than H^+ have no remarkable influence on the measurement.The ion activity ratio of K^+ to Na^+ measured directly in soil suspension agree well with those in centrifuged supernant solution.The relative deviation was within 4%.From the measured ion activity ratio,the difference of the bonding energies of K^+ and Na^+ ions was calculated.

Preparation of CeO_2 Nanoparticles and Its Application to Ion-selective Electrodes Based on Acetyl Cellulose

CeO2 nanoparticles with an average diameter of about 30 nm were prepared by sol-gel method at lower temperature. The gel, transformed from the aqueous solution of metal nitrate and citric acid, can be combusted completely at lower temperature. The redox behavior and the crystallization process of the dried gel were studied by thermogravimetric analysis and infrared spectroscopy. The synthesized powders were characterized by X-ray powder diffraction and transmission electron microscopy. In addition, rare earth elements ion-selective electrodes based on acetyl cellulose were prepared using ultra fine cerium oxide powders.

Construction and Application of a PVC Membrane Enoxacin Ion-selective Electrode Based on a Needle-shaped Inner Reference Electrode

A PVC membrane enoxacin ion-selective electrode based on a needle-shaped inner reference electrode was prepared. A Ag/AgCl wire was used as the substrate of this electrode. It was previously coated with a thin sheet of urea-formaldehyde resin containing Cl - ions to form a needle-shaped inner reference electrode, then the inner reference electrode was coated with a thin sheet of a PVC membrane containing an enoxacin tetraphenylborate ion-pair complex. The influences of various ion-pair complexes, concentrations of the active components in the membrane and the plasticizers on the performance of the electrode were studied by orthogonal design. The linear response range of the electrode was 7.9×10 -5 -1.0×10 -2 mol/L. The detection limit was 2.0×10 -5 mol/L. The slope was 30.4 mV/decade(25 ℃). The electrode can be used for the potentiometric determination of enoxacin tablets directly. The average recovery was 100.4%, and the RSD was 0.9%. The results agreed with those determined by the method in Chinese Pharmacopoeia.

Potentiometric Urea Biosensor Based on Ion-Selective Electrode by Different Immobilization Procedures

Enzyme was immobilized on an ammonium ion-selective electrode by different methods.An ion-selective electrode is not completely ion-specific,and interfering ions react with the ion-selective electrode membrane,altering the measured potential.Therefore,the characteristics of the effect of other ions on ammonium ion-selective electrode-based urea biosensors are considered.Based on the experimental results,the urea biosensor based on entrapment had a high response voltage of around 189 mV and fast response time of around 16 sec.Moreover,selectivity of the urea biosensor in different interfering ions was considered to elucidate the characteristics of ammonium ion-selective electrode-based biosensors.

STUDY OF CALCIUM ION-SELECTIVE ELECTRODE BASED ON A NEW NEUTRAL CARRIER

A calcium ion-setective eletrode based on a new neutral carrier was studied.The electrode gives a Nernstian response in the rang 5.9-1 Pa and the response is stable in a wide pH range.Logarithms of setectivity coefficents are -2.3 Li(+),-3.5 Na(+),-4.0 K(+),-3.7NH_4(+),-4.5 Mg(2+) and -4.4Zn(2+).

Nonaqueous potassium-ion full-cells:Mapping the progress and identifying missing puzzle pieces

This review addresses the growing interest for potassium-ion full-cells(KIFCs)in view of the transition from potassium-ion half-cells(KIHCs)toward commercial K-ion batteries(KIBs).It focuses on the key parameters of KIFCs such as the electrode/electrolyte interfaces challenge,major barriers,and recent advancements in KIFCs.The strategies for enhancing KIFC performance,including interfaces co ntrol,electrolyte optimization,electrodes capacity ratio,electrode material screening and electrode design,are discussed.The review highlights the need to evaluate KIBs in full-cell configurations as half-cell results are strongly impacted by the K metal reactivity.It also emphasizes the importance of understanding solid electrolyte interphase(SEI)formation in KIFCs and explores promising nonaqueous as well as quasiand all-solid-state electrolytes options.This review thus paves the way for practical,cost-effective,and scalable KIBs as energy storage systems by offering insights and guidance for future research.

A comparative study of four 20-membered N_2S_4-crown ethers as ionophores for polymeric membrane silver selective electrodes

Four 20-membered N_2S_4-monoazathiacrown ethers have been synthesized and explored as neutral ionophores for Ag^+-selective electrodes.Potentiometric responses reveal that the flexibility of the ligands has great effect on the selectivity and sensitivity to Ag^+ ions.The electrode based on ionophore 9,10,20,25-tetrahydro-5H,12H-tribenzo[b,n,r][1,7,10,16,4,13]tetrathiadiaza cycloicosine 6,13-(7H,14H)-dione(C) with 2-nitrophenyl octyl ether(o-NPOE) as solvent in a poly(vinyl chloride)(PVC) membrane matrix sho...

Chemically Modified Carbon Paste Electrode for Determination of Cesium Ion by Potentiometric Method

A new chemically modified carbon paste electrode for cesium(I) ion determination based on potassium zinc hexacyan-oferrate (PZHCF) as an ionophore was prepared. The electrode exhibits a Nernstian response for Cs(I) ions over a wide concentration range from 1 × 10-6 to 1 × 10-1 mol·L-1 with a slope of 58 ± 0.5 mV·decade-1. It has a response time of about 35 s and can be used for a period of 3 months with good reproducibility. Detection limit obtained in the optimal conditions was 3 × 10-7 mol·L-1. The potentiometric response is independent of the pH of the solution in the pH range 4.0 - 8.0. The electrode possesses the advantages of low resistance, fast response over a variety of other cations. The proposed electrode is applied as a sensor for the determination of Cs(I) ion concentration in different samples solutions. The results showed a good correlation with the data obtained by atomic absorption spectrometric method.

Metal Free Polymer/Graphite Electrode-Ferricyanides Catholyte System for MFC with High Performance

A Microbial fuel cell(MFC)with metal free polymer/graphite electrodes(150 mm×150 mm)was constructed.The electrodes with flowing channels,which were different in roughness,were designed.No additional catalyst was coated on the electrode,therefore the MFC was cheaper and possessed good durability with high performance.The effect of roughness,K3Fe(CN)6 concentration and sprayed air on the performance of the constructed MFC was investigated.Results showed that the roughness of electrode can significantly affect the performance of MFC.The power density of MFC increased by 1.56 times owing to the arithmetic mean roughness which has increased by 1.41 times.With an increasing K3Fe(CN)6 concentration,the performance of MFC also improves.The MFC with K3Fe(CN)6 only(30 mM)showed the highest power density of 1260 mW/m2,which is by 21.4 times and 1.3 times higher than those of MFCs with spraying air only(59 mW/m2)and with K3Fe(CN)6+air(1005 mW/m2),respectively.This showed that the appropriate concentration of K3Fe(CN)6 can significantly improve the power density,while the air has a negative effect when it is sprayed onto K3Fe(CN)6 catholyte.A coulombic efficiency of 34.2%and an energy efficiency of 13.3%with a COD degradation rate of 73.5%were achieved with MFC using K3Fe(CN)6 only.The overpotentials of MFC were also calculated.It can be seen that both theηohmic andηconcentration were very low as compared to theηactivation,and theηconcentration can be ignored because its effect was less than 3 mV.The theoretical calculation suggested that with an increasing conversion rate of K3Fe(CN)6,the cathode potential decreased and reached 0.31 V at a conversion rate of 0.99.While the anode behaves differently for constant pH and changeable pH as the reaction progresses,which reveals that the buffer solution and removal of protons play an important role in maintaining the anode potential.

Two Types of Potential Oscillation During the Reduction of Dichromate on Gold Electrode in H2SO4 Solution

潜在的摆动的二种不同类型在一个答案在一个金电极上在重铬酸盐减小期间第一次被识别了冲淡硫磺的酸。一个人由于形成在氢进化前发生，使钝化的溶解低原子价的铬氧化物拍摄，并且其它产生伴随周期的氢进化，从联合有散开、对流的集体运输的电气化学的反应。更有趣地，摆动的这二种类型在周期的 voltammogram (CV ) 对应于二个十字路口环。有穿过的 CV 的摆动的如此的一种关系将提供一个新方法系统地并且很快发现电气化学的摆动的系统。

Studies on the Gold-Coated Electrode with Grid

Introduction Thin-layer spectroelectrochemical method has many unique advantages, therefore this method has been widely applied and developed. Recently light transparent thinlayer spectroelectrochemical cells with various types of structures have been reported at home and abroad with gold or platinum minigrids as the working electrode in most of

Ion Selective Electrode Array Analysis Using Variable Step-Size Generalized Simulated Annealing

A global optimum location algorithm called Variable Step-Size Generalized Simulated Annealing(VSGSA) was applied to treating the data obtained by using an array of ion-electrodes in solutions containing mixtures of Na+, K+, Ca2+. Unlike traditional optimization algorithms such as simplex procedure, VSGSA can be used to determine the model parameters without any priori information about the analytical system under investigation and overcome the disadvantage of simplex method which might converge to local extrema depending on the starting positions. The algorithm was applied to po-tentiometric determination of ions in mixture solutions.

Binding mechanism of halide ions to bovine serum albumin and hemoglobin: investigated by ion selective-electrode

The binding mechanism of the interactions of halide ions (F–, Br– and I–) with bovine serum albumin (BSA) and hemoglobin (Hb) were studied at different temperatures, by using ion-selective electrodes. The experimental data were treated according to Klotz equation, and the number of binding sites and the binding constants were determined. The results show that the binding sites of F– on protein molecules are more than those of Br– and I–. Additionally, the number of the binding sites for halide ions on protein molecules increases with increasing temperature. This study also indicates that the binding constants for the interactions of halide ions with proteins gradually decrease as the size of halide ions and temperature increases. These behaviors were reasonably interpreted with the structural and thermodynamic factors. The thermodynamic functions at different temperatures were calculated with thermodynamic equations, and the enthalpy change for the interactions were also determined by isothermal titration calorimetry (ITC) at 298.15 K, which indicate that the interactions of halide ions with proteins are mainly electrostatic interaction.

Coulometric Response of H-Selective Solid-Contact Ion-Selective Electrodes and Its Application in Flexible Sensors+

The analytical performance of H+-selective solid-contact ion-selective electrodes(SCISEs)based on solid contact polyaniline doped with chloride(PANI(Cl))and poly(3,4-ethylenedioxythiophene)doped with poly(styrene sulfonate)(PEDOT(PSS))was characterized by a developed coulometric signal transduction method.PEDOT(PSS)solid contact is covered by PVC based H+-selective membrane.The obtained coulometric signal demonstrates that the cumulated charge can be amplified by increasing the capacitance of solid contact.SCISEs covered with spin-coated membrane behave faster amperometric response than electrodes with drop-cast mem-brane.In contrast to earlier works,the amperometric response and impedance spectrum demonstrates H+transfer through SCISEs is independent from the thickness of membrane.The exceptional behavior of PANI(Cl)H+-SCISEs shows that the capacitance estimated from impedance spectrum at low frequency 10 mHz and coulometric signal of PANI(Cl)based SCISEs is influenced by the applied po-tentials,whereas PEDOT(PSS)solid contact is independent from the chosen applied potentials.Furthermore,preliminary investiga-tions of coulometric signal transduction on flexible pH sensor implies its potential applications in wearable sensors for sweat ion concentration detection.

锑基材料在钾离子电池负极中的应用

近年来,随着可再生能源和电动设备的广泛应用,储能技术的发展变得至关重要。目前,锂离子电池(LIBs)由于具有较高的能量密度而备受关注,但是又因原料成本过高限制了其在未来市场中的应用。在地壳和海洋中,钾元素的天然丰度及其低的氧化还原电位使得钾离子电池(PIBs)成为了LIBs的潜在替代品。然而,由于K+的半径较大,PIBs通常表现出缓慢的反应动力学。目前,PIBs的电极材料研究仍处于初步阶段。其中,Sb基材料(如Sb、Sb 2S 3、Sb 2Se 3)具有较高的理论储钾容量,成为了当前研究的热点。本文从材料制备、结构优化和性能提升的角度,阐述了Sb基材料在PIBs中的重要进展。在此基础上,本文探讨了Sb基材料面临的挑战和未来的发展方向,并提出了改进建议,以期为Sb基材料的技术进步提供新的思路。

钾离子电池碳基负极材料研究进展

随着锂电池的大范围应用,锂资源匮乏及其价格升高逐渐成为一个全球性的问题。钾离子电池以其原料储量丰富的优点,有望成为锂离子电池的替代品。各类钾电池负极材料中,碳基材料价格低廉,并且有着特殊的多孔结构、良好的导电性以及稳定的电极特性。从软碳、硬碳、石墨三方面综述了近年来国内外钾电池碳基负极材料的相关研究,分析总结了材料改性方法和材料的比容量、循环性能、倍率性能及其影响因素,展望了钾电池碳基负极材料在实现高可逆容量、长循环稳定性等方面的发展方向。

An all-organic aqueous potassium dual-ion battery

Benefiting from the environmental friendliness of organic electrodes and the high security of aqueous electrolyte,an all-organic aqueous potassium dual-ion full battery(APDIB) was assembled with 21 M potassium bis(fluoroslufonyl)imide(KFSI) water-in-salt as the electrolyte.The APDIB could deliver a reversible capacity of around 50 mAh g^(-1) at 200 mA g^(-1)(based on the weight of total active materials),a long cycle stability over 900 cycles at 500 mA g^(-1) and a high coulombic efficiency of 98.5%.The reaction mechanism of APDIB during the charge/discharge processes is verified:the FSI-could associate/disassociate with the nitrogen atom in the polytriphenylamine(PTPAn) cathode,while the K^(+) could react with C=O bonds in the 3,4,9,10-perylenetetracarboxylic diimide(PTCDI) anode reversibly.Our work contributes toward the understanding the nature of water-into-salt electrolyte and successfully constructed all-organic APDIB.

Sodiophilicity/potassiophilicity chemistry in sodium/potassium metal anodes

Heteroatom-doped carbon materials have been widely used as sodium(Na) and potassium(K) metal anode frameworks to achieve uniform Na and K depositions. If the origin of the Sodiophilicity and potassiophilicity of doping sites in heteroatom-doped carbon host are clearly understood, the nucleation and growth behavior of Na and K can be precisely regulated in working batteries. Herein the Sodiophilicity and potassiophilicity chemistries of carbon materials are probed through first-principles calculations. The local dipole of doping functional groups and charge transfer during Na/K deposition are regarded as key principles to reveal the sodiophilic and potassiophilic nature of doping sites. Especially, O–B, O–S, and O–P co-doping strategy are predicted to be effective methods to improve the Sodiophilicity and potassiophilicity of carbon hosts and thus render safe and dendrite-free Na and K metal anodes. This work affords a deep and insightful understanding of Sodiophilicity and potassiophilicity chemistry of Na and K anodes and establishes general principles of designing highly sodiophilic and potassiophilic carbon frameworks.

Adsorption of Potassium and Calcium Ions by Variable Charge Soils

Interactions of potassium and calcium ions with four typical variable charge soils in South China were examined by measuring pK-0.5pCa value with a potassium ion-selective electrode and a calcium ion-selective electrode,and pK value with a potassium ion-selective electrode.The results showed that adsorption of potassium and calcium ions increased with soil suspension pH,and the tendency of the pK-0.5pCa value changing with pH differed with respect to pH range and potassium to calcium ratio.Adsorption of equal amount of calcium and potassium ions led to release of an identical number of protons,suggesting similar adsorption characteristics of these two ions when adsorbed by variable charge soils.Compared with red soil,latosol and lateritic red soil had higher adsorption selectivities for calcium ion.The red soil had a greater affinity for potassium ion than that for calcium ion at low concentration,which seems to result from its possession of 2:1 type minerals,such as vermiculite and mica with a high affinity for potassium ion.The results indicated that adsorption of potassium and calcium ions by the variable charge soils was chiefly caused by the electrostatic attraction between the cations and the soil surfaces.Moreover,it was found that sulfate could affect the adsorption by changing soil surface properties and by forming ion-pair.