氢氧化钽及其焙烧产物对磷酸盐的吸附

研究了氢氧化钽原样及其焙烧产物对磷酸盐的吸附行为,考察了吸附剂用量,吸附时间,焙烧温度,共存阴离子对吸附量的影响以及焙烧温度对吸附剂物理化学性质的影响。结果表明,在磷酸盐初始浓度为50 mg/L,温度为25℃,吸附剂投加量为0.4 g/L,pH值为2的条件下,30 min达到吸附平衡,原样及100℃,200℃3,00℃焙烧后产物的吸附量依次为55.88 PO43-mg/g,27.17 PO34-mg/g,8.78 PO34-mg/g,8.45 PO34-mg/g,而400℃,500℃焙烧产物对磷酸盐不具有吸附性,可见焙烧后吸附剂的吸附能力明显降低。常见共存阴离子(SO24-,Cl-,NO3-)几乎不影响磷酸盐的吸附。热重、红外谱图分析表明随着焙烧温度的升高氢氧化钽的表面活性基团(NH4+,-OH)逐渐消失,并且吸附性能也渐消失。     

Removal of transition metal cations and their counteranions by crosslinked epoxy—polymer

Reaction of epichlorohydrin with ethylenediamine is very exothermic, and severe explosions occur, even when a few milliliters of the reagents are interacted without solvent. A controlled reaction has been achieved safely by suspension polycondensation of epichlorohydrin with ethylenediamine. 1,2-Diaminoethane units in the resulting crosslinked polymer provide high chelating ability for transition metal ions, such as Cu(II), Ni(II), Co(II), Cd(II), Fe(III), and Cr(III). Having all-amine ligating groups, the polymer represents unique properties and can sorb not only metal cations but also their counteranions, such as chloride, sulphate, nitrate, and acetate. The crosslinked polymer is stable hydrolytically and regenerable by acid without losing its activity. It can be recycled and offers a means of simultaneous removal of cations and anions from aqueous solutions. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 103–109, 1998     

Removal of As(V) from wastewaters by chemically modified fungal biomass

Biosorption has been demonstrated to be a useful alternative to conventional treatment systems for the removal of toxic metals from dilute aqueous solution. The objective of this paper was to examine the main aspects of a possible strategy for the removal of arsenates, employing P. chrysogenum biomass. The pretreatment of biomass with common surfactants (as hexadecyl-trimethylammonium bromide and dodecylamine) and a cationic polyelectrolyte was found to improve the biosorption efficiency. The initial biomass showed a relative low affinity for metallic anions, whereas with the application of modified samples a significant uptake of arsenic was observed. Sorption data were well described by typical Langmuir and Freundlich adsorption isotherms. Promising results were obtained in laboratory experiments and effective As(V) removals were observed.     

Overcoming Obstacles in Zn-Ion Batteries Development: Application of Conductive Redox-Active Polypyrrole/Tiron Anolyte Interphase

This study is focused on overcoming obstacles in the implementation of metallic Zn for zinc-ion batteries. The major limiting factors of Zn anodes include dendrite growth, hydrogen evolution, and by-product formation. Herein, the challenges are addressed by the application of a redox-active electrode-electrolyte interphase. Cationic polypyrrole(PPy)/anionic Tiron anolyte is formulated as the mixed conducting interphase to push the limits of zinc-based energy storage. The doping/de-doping behavior of PPy stimulates the surface adsorption/desorption of Tiron attributed to the ion-induced nucleation. Testing results show that PPy as a passivating corrosive-resistant layer improves the interfacial stability of Zn metal; while releasing the redox-active anolyte boosts the charge transfer of cells by the phenol-quinone transformations. The Zn//Zn cells demonstrate an improved life from 50 to 2500 cycles with a reduced overpotential at 2 mA cm⁻² and 1 mAh cm⁻². In situ UV–vis spectroscopic measurements, combined with density functional theory calculations, address the redox mechanisms of PPy/Tiron anolyte. The testing of α-MnO₂//Zn cells shows that the PPy/Tiron anolyte exhibits enhanced capacity and rate performance due to the pseudocapacitive effects. This study unveils a conceptually new approach based on the modification of conducting polymer with redox-active dopants toward the fabrication of high-performance Zn-anolyte batteries.     

Importance of anionic reactive intermediates for lubricant component reactions with friction surfaces

To understand the chemical behaviour of lubricant components during boundary lubrication, a general concept of negative ionradical reactive intermediates formation for these components has been proposed. The concept is based upon the ionisation mechanism of these compounds caused by the action of electrons of law energy (1–4 eV). Electrons of such energy (exoelectrons) are spontaneously emitted from most fresh surfaces formed during friction. The principal thesis of the model is that lubricant components form anions which are then chemisorbed on the positively charged areas of rubbing surfaces. The formation of negative ions and their decomposition process are simulated by electron attachment mass spectrography. This type of mass spectrography uses electrons of an energy range similar to those of exoelectrons. The proposed model encompasses the following major stages: (a) low-energy electron emission process and creation of positively charged spots, (b) action of emitted electrons with lubricant components (anion and radical formation), (c) reactions of anions with metal surfaces forming a film protecting the surface from wear, (d) cracking of chemical bonds producing other radicals. The model explains many lubrication phenomena of hydrocarbons, oxygen-containing compounds, and many types of chemicals used as antiwear and extreme-pressure additives.