Poly-thiosemicarbazide/gold nanoparticles catalytic membrane: In-situ growth of well-dispersed, uniform and stable gold nanoparticles in a polymeric membrane

Use of the O2-Thiosemicarbazide System, for the Leaching of: Gold and Copper from WEEE & Silver Contained in Mining Wastes

Environmental pollution today is a latent risk for humanity, here the need to recycle waste of all kinds. This work is related to the kinetic study of the leaching of gold and copper contained in waste electrical and electronic equipment (WEEE) and silver contained in mining wastes (MW), using the O2-thiosemicarbazide system. The results obtained show that this non-toxic leaching system is adequate for the leaching of said metals. Reaction orders were found ranging from 0 (Cu), 0.93 (Ag), and 2.01 (Au) for the effect of the reagent concentration and maximum recoveries of 77.7% (Cu), 95.8% (Au), and 60% (Ag) were obtained. Likewise, the activation energies found show that the leaching of WEEE is controlled by diffusion (Cu Ea = 9.06 and Au Ea = 18.25 kJ/Kmol), while the leaching of MW (Ea = 45.55 kJ/Kmol) is controlled by the chemical reaction. For the case of stirring rate, it was found a low effect and only particles from WEEE and MW must be suspended in solution to proceed with the leaching. The pH has effect only at values above 8, and finally, for the case of MW, the O2 partial pressure has a market effect, going the Ag leaching from 33% at 0.2 atm up to 60% at a 1 atm.

Preparation of Hierarchical Highly Ordered Porous Films of Brominated Poly(phenylene oxide) and Hydrophilic SiO₂/C Membrane via the Breath Figure Method

Porous permeable films materials have very broad prospects in the treatment of sludge-containing waste water due to their large surface area and good microfiltration. In this work, highly ordered porous membranes have been prepared successfully on ice substrates using a poly(phenylene oxide) (BPPO)-SiO₂ nanoparticle (NP) mixture by the brePorous permeable films materials have very broad prospects in the treatment of sludge-containing waste water due to their large surface area and good microfiltration. In this work, highly ordered porous membranes have been prepared successfully on ice substrates using aath figure method. Based on the theory of Pickering emulsion system and capillary flow, particle assisted membrane formation was analyzed. Another two sorts of new membranes SiO₂/C membrane and hierarchical porous polymer (HPP) membrane, which were obtained by modification of the BPPO-SiO₂ membrane by calcination and etching, were set up in a further study. Their properties were investigated through the methods of scanning electron microscopy (SEM), fourier transform infrared spectrometry (FTIR), ultraviolet spectrum (UV), capillary electrophoresis (CE), contact angle, and water flux tests. All these results demonstrate that both surface hydrophilicity and fouling resistance of the membrane would be improved by using SiO₂ as a filler. The membranes with high permeability and antifouling properties were used for microfiltration applications.

Simultaneous AuIII Extraction and In Situ Formation of Polymeric Membrane-Supported Au Nanoparticles: A Sustainable Process with Application in Catalysis

A polymeric membrane-supported catalyst with immobilized gold nanoparticles (AuNPs) was prepared through the extraction and in situ reduction of Au^III salts in a one-step strategy. Polymeric inclusion membranes (PIMs) and polymeric nanoporous membranes (PNMs) were tested as different membrane-support systems. Transport experiments indicated that PIMs composed of cellulose triacetate, 2-nitrophenyloctyl ether, and an aliphatic tertiary amine (Adogen 364 or Alamine 336) were the most efficient supports for Au^III extraction. The simultaneous extraction and reduction processes were proven to be the result of a synergic phenomenon in which all the membrane components were involved. Scanning electron microscopy characterization of cross-sectional samples suggested a distribution of AuNPs throughout the membrane. Transmission electron microscopy characterization of the AuNPs indicated average particle sizes of 36.7 and 2.9 nm for the PIMs and PNMs, respectively. AuNPs supported on PIMs allowed for >95.4 % reduction of a 0.05 mmol L^-1 4-nitrophenol aqueous solution with 10 mmol L^-1 NaBH₄ solution within 25 min.

Polymer and Membrane Design for Low Temperature Catalytic Reactions

Catalytically active asymmetric membranes have been developed with high loadings of palladium nanoparticles located solely in the membrane's ultrathin skin layer. The manufacturing of these membranes requires polymers with functional groups, which can form insoluble complexes with palladium ions. Three polymers have been synthesized for this purpose and a complexation/nonsolvent induced phase separation followed by a palladium reduction step is carried out to prepare such membranes. Parameters to optimize the skin layer thickness and porosity, the palladium loading in this layer, and the palladium nanoparticles size are determined. The catalytic activity of the membranes is verified with the reduction of a nitro-compound and with a liquid phase Suzuki-Miyaura coupling reaction. Very low reaction times are observed.

An electrochemical sensor for nitrobenzene using π-conjugated polymer-embedded nanosilver

A novel electrochemical sensing platform for nitrobenzene has been developed using silver nanoparticles (AgNPs) embedded in the poly(amic) acid (PAA) polymer matrix (PAA–AgNPs).

Complexation-induced phase separation: preparation of composite membranes with a nanometer-thin dense skin loaded with metal ions

We present the development of a facile phase-inversion method for forming asymmetric membranes with a precise high metal ion loading capacity in only the dense layer. The approach combines the use of macromolecule-metal intermolecular complexes to form the dense layer of asymmetric membranes with nonsolvent-induced phase separation to form the porous support. This allows the independent optimization of both the dense layer and porous support while maintaining the simplicity of a phase-inversion process. Moreover, it facilitates control over (i) the thickness of the dense layer throughout several orders of magnitude from less than 15 nm to more than 6 μm, (ii) the type and amount of metal ions loaded in the dense layer, (iii) the morphology of the membrane surface, and (iv) the porosity and structure of the support. This simple and scalable process provides a new platform for building multifunctional membranes with a high loading of well-dispersed metal ions in the dense layer.

Triazole-stabilized gold and related noble metal nanoparticles for 4-nitrophenol reduction

The preparation of N-substituted triazole–polyethylene glycol-stabilized metal nanoparticles and their high catalytic activities for 4-nitrophenol reduction.