Ammonium Persulfate Concentration Research Articles

Conductive fabric patch with controllable porous structure and elastic properties for tissue engineering applications

Cardiovascular disease has gradually become a kind of lifestyle disease in modern society, and the construction of an engineered cardiac patch (ECP) through tissue engineering means is a promising treatment for myocardial infarction in clinical practice. In this study, polyamide fabric was used as scaffold material. Hydrochloric acid, aniline (AN), and ammonium persulfate (APS) were used as main modification reagents. The knitted ECP was constructed by straight in situ polymerization. Respectively, by using a single variable method to change the concentration of APS and base fabric knit method, through a series of tests analyzing the effect of APS concentration and knitting methods on ECP properties, the optimal preparation of ECP was summarized: under the experimental conditions of hydrochloric acid, AN, and APS solution concentrations of 0.7 mol L−1, the ECP showed the best performance for potential cardiac therapy application: the conductivity can reach 2.63–2.79 S m−1, porosity is 60–62%, average pore size is in the range of 16.4–21.65 μm, and elongation is up to 181.43%, showing superior properties of textiles cardiac patch.

Tailored synthesis of hydrogel media for chirality separation of single walled carbon nanotubes

An alternative approach toward understanding and advancing hydrogel-based single walled carbon nanotube (SWNT) purification is described and employed. Experimental and atomistic modeling analysis of the leading hydrogel for SWNT purification, Sephacryl S200, affords creation of gels that mimic its behavior in terms of dependent SWNT interaction and SWNT purification properties. This achievement introduces a generalized approach toward optimization of SWNT purification media with respect to the components of Sephacryl. Here, the role of the radical initiator ammonium persulfate (APS) in hydrogel-based SWNT purification is explored through synthesis and characterization of gels containing varied APS concentration, and thus, varied amounts of covalently embedded charged organosulfate groups (R–SO4-). The presence of these moieties plays a significant role in SWNT-gel interactions: at decreasing APS concentration SWNT uptake is increased, the chiral profiles of purified SWNT are altered, and a greater fraction of adsorbed material is recovered. Tailored hydrogels containing minimal APS exhibit improved SWNT adsorption vs. Sephacryl. These findings warrant proposition of a four-step qualitative model that deconvolutes electrostatic and steric effects within SWNT/surfactant/hydrogel systems. Collectively, this work demonstrates enhanced methodology for hydrogel-based SWNT purification and lays the foundation for further optimization of the gel medium.

Optimum oxidation for direct and efficient extraction of carboxylated cellulose nanocrystals from recycled MDF fibers by ammonium persulfate

For the first time, this study demonstrates a direct extraction of carboxylated cellulose nanocrystals (c-CNCs) from recycled medium density fiberboard (r-MDF) fibers by ammonium persulfate (APS) without any chemical pre-treatment. The aim of this research was to find an optimum condition for isolating c-CNCs from r-MDF fibers by studying the effect of reaction parameters on the characteristics of c-CNCs. The rod-like c-CNCs had an average length and width of 170 to 365 nm and 13 to 17 nm, leading to an aspect ratio of 13∼21. The optimum conditions for a maximum yield and crystallinity were obtained at a reaction temperature of 70 °C, reaction time of 16 h and APS concentration of 1.5 mol L˗1. Thermal analysis also revealed lower thermal stability of the c-CNCs compared to r-MDF fibers. The APS oxidation is a viable option for converting r-MDF fibers into value-added c-CNCs.

Use of Ammonia Salts in Selective Copper Extraction from Tailings

Tailings (flotation waste) that is formed during copper production may be considered in the class of valuable wastes due to the amount of copper it contains. Owing to the decreasing grade values in copper ores, utilization of wastes such as tailings that carry certain amounts of copper as secondary sources has become a necessity in both the economic and environmental sense. This study investigated the usage conditions of five different ammonia salts as leaching reactants for the purpose of selective extraction of copper from tailings. For this purpose, the effects of parameters such as leaching temperature and leaching time were examined at different concentrations of ammonium hydroxide, ammonium carbonate, ammonium nitrate, ammonium chloride, and ammonium persulfate. The copper extraction efficiency in the case of using the aforementioned salts by themselves were listed as (NH4)2CO3 (73%) > (NH4)2S2O8 (69%) > NH4OH (64%) > NH4Cl (42%) > NH4NO3 (40%). The highest copper extraction efficiency was obtained in the leaching process that was conducted with the solutions obtained by mixing ammonia salts in the best conditions. Accordingly, as a result of 6 h of leaching at 30 °C in the presence of 22.5% NH4OH and 100 g/L (NH4)2S2O8, 91.47% of the copper was transferred into the solution, while iron was not transferred. The obtained results showed that copper could be selectively recovered from tailings.

Synthesis of Grafted Cationic Starch with DMDAAC Using Ammonium Persulfate/Carbamide Initiation System

Using ammonium persulfate (APS)/carbamide initiation system, cationic grafted starch was prepared by the graft copolymerization of starch with diallydimethylammonium chloride (DMDAAC). The synthesized polymer was confirmed by FTIR, NMR, and XRD. And the morphology was characterized by SEM. The optimum conditions of graft copolymerization were determined and the flocculation properties of the cationic grafted starch were investigated using diatomite suspension. The obtained results showed that grafting ratio (G) and grafting efficiency (GE) have an increased trend along with the increase of mass ratio of starch to monomer. G, GE and cationic degree (DC) increased with the rise of mole ratio of AM to DMDAAC. When the total concentration of the monomers in the system is fixed, increasing APS concentration up to 0.33×10-3 M caused a rise for the G, GE and DC. The optimum temperature and the time were 40 °C and 5 h, respectively. The result also showed that the cationic grafted starch has excellent flocculation performance whether in acid, alkaline or neutral conditions.

Superhydrophobic Polypyrrole-Coated Cigarette Filters for Effective Oil/Water Separation

To facilitate the recycling and reuse of cigarette filters and oil/water separation, a superhydrophobic cigarette filter was made by coating with dodecanethiol-modified polypyrrole (Ppy) particles by a dip-coating method. SEM, FTIR, and XPS were used to analyze the surface morphology and chemical compositions. The as-prepared superhydrophobic cigarette filter can realize wettability alteration via changing the ammonium persulfate (APS) concentration from 0.15 mol/L to 3 mol/L, and the contact angle increased from 0° on the original cigarette filter to 155° with a sliding angle of 5°. The superhydrophobic cigarette filter could effectively separate various oils and organic solvents. The separation efficiency was 98.8% and the separation stability was good. Furthermore, the as-prepared superhydrophobic cigarette filter had a large oil absorption range and could absorb different oils and organic solvents, including petroleum ether, engine oil, vegetable oil, n-hexane, and chloroform, with maximum absorption capacities ranging from 9.4 g/g to 22.7 g/g. According to the above results, we believe that the as-prepared superhydrophobic cigarette filter should have great potential in the recovery of solid waste and high-efficiency oil/water separation.

A facile template-free strategy for synthesizing hydroxymethyl-poly(3,4-ethylenedioxythiophene) nanospheres

Hydroxymethyl-poly(3,4-ethylenedioxythiophene)(PEDOT-OH) nanospheres self-assembled using physical blowing method, which continually used a syringe, were successfully formed through aqueous solution polymerization under the oxidative initiators. The effect of blowing on the morphological properties of PEDOT-OH was precisely evaluated based on the different amount of initiator. The concentration of ammonium persulfate might be a driving force in the self-assembly process to create the PEDOT-OH nanospheres. The electrical and electrochemical properties of the resulting nanospheres were also characterized using four-point probe and cyclic voltammetry.

Biodegradable and biocompatible agarose–poly (vinyl alcohol) hydrogel for the in vitro investigation of ibuprofen release

Biodegradable and biocompatible interpenetrating hydrogels consisting of agarose and poly (vinyl alcohol) (PVA) were synthesized using N,N′-methylene bisacrylamide as the cross-linker. Different hydrogels of agarose were prepared with varying concentration of PVA, cross-linker, and initiator ammonium persulfate. The concentration of each of the component was optimized on the basis of their nature of swelling. Surface morphology of the prepared hydrogel was examined by FESEM analysis and structural changes were confirmed by FTIR, XRD and TGA/DSC technique. Prepared hydrogels showed excellent swelling and pH-dependent drug release. Ibuprofen was used as a model drug to investigate the release behavior from hydrogels. Pre-synthesized IBU and β-cyclodextrin (1:1) inclusion complex was loaded directly into the hydrogel and its release study was performed in different pH solutions. The release data were fitted using various kinetic models such as zero-order, first-order, Higuchi model and Korsemeyer–Peppas model and examined the release mechanism. The biodegradation and cytotoxicity assay studies confirmed the degradable and non-toxic nature of modified hydrogel.

One-pot green synthesis of carboxylated cellulose nanocrystals through oxidative degradation of bamboo pulp

Carboxylated cellulose nanocrystals (CCN) were prepared from bamboo pulp by ammonium persulfate (APS) with an ultrasonication-assisted technique. The effects of ultrasonication time, APS concentration, and reaction temperature on the yield of CCN were investigated. The morphology, structure, crystallinity, and thermal properties of prepared samples were analyzed by transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). The CCN presented rod-like shapes with diameter ranging from 10 to 30 nm and length of 50 to 200 nm. FTIR showed that CCN still kept with the basic chemical structure of cellulose, and at the 1735 cm-1 appearing the peak of C=O. The XRD pattern indicated that CCN was characteristic of the cellulose I crystal form, and the crystallinity of CCN was 63%. TGA revealed that CCN had a lower thermal stability than bamboo pulp. This research explored a low-cost and eco-friendly way to prepare CCN.

Preparation and performance of PANI-TiO2 nanotube arrays composite electrode by in-situ microcavity polymerization

TiO2 nanotube arrays (TNTA) were firstly impregnated with ethanol solution containing aniline monomer, then the polyaniline-TiO2 nanotube arrays (PANI-TNTA) composite electrode was prepared through polymerization of aniline monomer in the microcavity of the nanotubes using ammonium persulfate (APS) as the initiator. The effects of aniline and APS concentration on the properties of the composite electrodes were studied. The electrochemical performances of the composite electrode in sodium sulfate aqueous solution and sulfuric acid aqueous solution were compared at different potential windows of −0.2–1 V and −0.2–1.8 V. Results show that the composite electrode exhibits optimal performance when the concentration of aniline and APS is 0.2 M and 0.05 M, respectively. The composite electrode has fair good electrochemical performances under various testing conditions especially in sulfuric acid aqueous solution, it has a maximum capacitance of 816.7 F g−1, and at the enlarged potential window of −0.2–1.8 V, its energy densities are higher than those of −0.2–1 V. The composite electrode also has excellent rate and cycling properties.

Effect of Ammonium Persulfate Concentration on Characteristics of Cellulose Nanocrystals from Oil Palm Frond

Cellulose nanocrystals (CNCs) were successfully isolated from oil palm fronds (OPFs) using different concentrations of ammonium persulfate (APS), and their characteristics were analyzed by Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), X-ray diffraction (XRD) analysis, and thermogravimetric analysis (TGA). APS oxidation effectively isolated CNCs with rod-like morphology in nanometer scale. The dimensions of the CNCs decreased with increasing APS concentration. FTIR and XRD analyses revealed that all the CNCs showed crystals in the form of cellulose I without crystal transformation occurring during APS treatment. The relative crystallinity of the CNCs increased with increasing APS concentration, whereas their thermal stability decreased. An APS concentration of 2 M was found to be optimal for isolating the CNCs.

Variation of Ammonium Persulfate Concentration Determines Particle Morphology and Electrical Conductivity in HCl Doped Polyaniline

Polyaniline (PANI) is one of conducting polymers which is widely used in various applications especially energy field, like solar cells and batteries. PANI emeraldine salt (PANI ES) is the only type of conducting PANI which can be easily synthesized using a direct mixing method in an oxidizing solution. Ammonium persulfate (APS) is one example of a strong oxidizing agent which is often used in PANI synthesis. The APS concentrations used in this study ranged from 0.1 to 1 M. Infrared and Raman spectroscopy shows that the addition of APS concentrations above 0.5 M produces the non-conducting fully oxidized PANI and phenazine species. Scanning electron microscope (SEM) showed morphological changes of PANI ES from nanofiber (diameter 80 - 110 nm) to granules (diameter 20 - 70 nm) as APS concentration increases. Based on Electrochemical impedance spectroscopy (EIS), conductivity of PANI increases as APS concentration increases with maximum conductivity of 0.36 S cm−1 at 0.5 M.

Dextran-graft-poly(hydroxyethyl methacrylate) biosorbents for removal of dyes and metal cations

Dextran-graft-poly(hydroxyethyl methacrylate) gels were prepared and used as a biosorbent for removal of dyes and heavy metal cations. For this propose, the effects of three main parameters during the preparation of gels including concentrations of monomer (hydroxyethyl methacrylate), the crosslinking agent (N,N’-methylenebisacrylamide (MBA)) and initiator (ammonium persulfate) on their swelling and absorbability of dyes and heavy metal cations were investigated. Methylene blue (MB) and rose bengal (RB) as model dyes and Fe(III) and Cu (II) as model metal cations were selected. Increasing the poly(hydroxyethyl methacrylate) content within the gels resulted in higher Equilibrium water absorption (EWA) values and consequently better dye and cation adsorption. Higher concentration of MBA led to lower dye adsorption values. Increasing the ammonium persulfate (APS) concentration did not change significantly the dyes and metal cations adsorption. The results indicated that this biosorbents system could be potentially used in the removal of heavy metal and dye from wastewater.

Extraction of oxidized nanocellulose from date palm (Phoenix Dactylifera L.) sheath fibers: Influence of CI and CII polymorphs on the properties of chitosan/bionanocomposite films

Packaging has increasingly become a dominant factor in the global market competitiveness. This implies we should obtain new raw materials with improved packaging properties. In particular, oxidized nanocelluloses, obtained from locally cultivated date palm sheath fibers, were extracted by ammonium persulfate treatment of unbleached pulp and mercerized date palm sheath fibers. The influence of reaction parameters (e.g. ammonium persulfate concentration 0.5–1.5 M, duration 8–20 h and temperature 50–80 °C) were studied. A significant particle size reduction, surface charge density diminishing and thermal stability enhancement resulted as a consequence of the ammonium persulfate hydrolysis. The extracted oxidized nanocelluloses, at the optimum conditions, were used as a packaging additive in chitosan films. The physicochemical and mechanical analyses of the resulting bionanocomposite films show potential improvements in water vapor barrier and strength properties.

Green acid-free one-step hydrothermal ammonium persulfate oxidation of viscose fiber wastes to obtain carboxylated spherical cellulose nanocrystals for oil/water Pickering emulsion

Textile manufacturing industries produce large amounts of viscose fiber wastes (VFW), causing serious environmental pollution. This study presents an acid-free approach to prepare spherical cellulose nanocrystals (SCNs) with carboxyl groups from industrial VFW by one-step hydrothermal ammonium persulfate (APS) oxidation. Novel double-response surface methodology was employed to optimize the reaction conditions. A maximum yield (37.89%) of carboxylated SCN was obtained at reaction time of 4 h, APS concentration of 1 M and temperature of 80 °C, while the SCNs showed gradual size reductions along with increase of carboxyl contents as reaction time and APS concentration increased. Interestingly, it was possible to obtain carboxylated SCNs in only 2 h of reaction with an increase of 16.5% in the crystallinity index, which was attributed to efficient swelling of cellulose chains and oxidation interaction of surface groups under hydrothermal condition. Compared with SCN-2 h, the crystallinity index and maximum degradation temperature of SCN-10 h were improved by 5.5% and 17.9 °C, respectively. Moreover, SCN-10 h exhibited excellent emulsifying capacity to stabilize soybean oil/water Pickering emulsion droplets and emulsion volume were increased with decreased mean diameter of emulsion droplets as SCN-10 h concentration increased. These results indicate that VFW is an attractive source to produce carboxylated SCNs by APS oxidation, making SCN extraction as value-added alternatives to recycle this waste. Such carboxylated SCNs have great potentials as green food Pickering emulsion stabilizers and nanofillers in high-performance composites.

Grafting of N-vinyl-2-pyrrolidone onto κ-carrageenan for silver nanoparticles synthesis

A water soluble, non-gel, poly (N-vinyl-2-pyrrolidone)/κ-carrageenan (PVP/KC) hybrid was synthesized by graft copolymerization of N-vinylpyrrolidone (VP) onto κ-carrageenan in an aqueous medium using ammonium persulphate (APS) as an initiator. Factors affecting the polymerization reaction such as ammonium persulfate concentration, reaction temperature and time, liquor to KC ratio (LR) and KC to VP molar ratio were studied. The results obtained revealed that the optimum reaction polymerization conditions to prepare that hybrid with a total conversion of 93.9% are: [VP], 0.1799 mol/L; VP/KC molar ratio, 50%; [APS], 0.0105 mol/l; LR, 15 l/k; reaction temperature, 90 °C and reaction time, 75 min. Moreover, the grafted KC of that hybrid was characterized via investigating its FTIR analysis. Furthermore, the potential application of such hybrid as a route for synthesis of silver nanoparticles (Ag NPs) using AgNO3 as a precursor was investigated. The synthesized Ag NPs are characterized using the ultraviolet-visible spectroscopy (UV–vis) as well as transmission electron microscope (TEM). The UV–vis showed a band at 435 nm that confirms the presence of Ag NPs. The TEM image shows that such nanoparticles have a spherical structure with an average size ranging from 3 −18 nm.

Moringa gum-g-poly(N-vinyl-2-pyrrolidone) – a potential buccoadhesive polymer

In the present study, MG-g-poly(NVP) was synthesized using microwave-assisted graft co-polymerization reaction. Synthesis of graft co-polymer was optimized using response surface methodology. The influence of concentration of Moringa gum, N-vinyl-2-pyrrolidone and ammonium persulfate on grafting efficiency of graft copolymer was studied using 3-factor, 3-level central composite experimental design. The optimal calculated parameters were found to be concentration of Moringa gum-1% (w/v), N-vinyl-2-pyrrolidone-2% (w/v), and ammonium persulfate–10 mMol/L, which yielded a graft co-polymer of% grafting efficiency (24.23%). The graft co-polymer were further characterized by Fourier-transform infrared spectroscopy, X-ray diffraction and scanning electron microscopy studies. The results of characterization revealed that grafting of N-vinyl-2-pyrrolidone on Moringa gum decreases its crystallinity and makes its surface smoother. Graft copolymer was further evaluated for pharmaceutical application by formulating clotrimazole-loaded buccal discs. A comparative evaluation of buccal discs of graft co-polymer with native gum revealed higher ex-vivo bioadhesion time and greater sustained release effect of the graft copolymer than of native gum.

New crosslinked-chitosan graft poly(N-vinyl-2-pyrrolidone) for the removal of Cu(II) ions from aqueous solutions

Crosslinked chitosan beads were grafted with N-vinyl-2-pyrrolidone (NVP) using ammonium persulfate (APS) as free radical initiator. Important variables on graft copolymerization such as temperature, reaction time, concentration of initiator and concentration of monomer were optimized. The results revealed optimum conditions for maximum grafting of NVP on 1g crosslinked chitosan as follows: reaction temperature, 60°C; reaction time, 2h and concentrations of APS and NVP of 2.63×10−1M and 26.99×10−1M, respectively. The modified chitosan beads were characterized by FTIR spectroscopy, 13C NMR, SEM and BET to provide evidence of successful crosslinking and grafting reactions. The resulting material (cts(x)-g-PNVP) was evaluated as adsorbent for the removal of Cu(II) ions from aqueous solutions in a batch experiment. The Langmuir and Freundlich adsorption models were also applied to describe the equilibrium isotherms. The results showed that the adsorption of the copper ions onto the beads agreed well with Langmuir model with the maximum capacity (qmax) of 122mgg−1.

Recycling non-leaching gold from gold-plated memory cards: Parameters optimization, experimental verification, and mechanism analysis

Large amounts of gold generally plated on printed circuit boards that drives unregulated activities to recycle it with serious adverse consequences to the environment and human health, demanding innovative strategies to solve this problem. This paper presented a novel, efficient and safer strategy to recover non-leaching gold from waste memory cards by using the renewable agent ammonium persulfate and hydrogen peroxide, which were evaluated in terms of efficiency and kinetics. The tests were conducted in a response surface methodology design called central operation design. The results showed that the optimal conditions were 0.8 mol/L of ammonium persulfate concentration (1:30 of solid/liquid ratio), 14.45 mL of hydrogen peroxide dosage, 80 °C of reaction temperature and 30 min of reaction time, under which the recovery rate of gold was 98.95% with 93.105% purity. This process of gold peeling agreed with the shrinking core model controlled by diffusion. All findings demonstrated that combination of ammonium persulfate and hydrogen peroxide has a good performance for oxidizing base metal substrate and peeling superficial gold from memory cards.

One-Step Synthesis of Hollow Dimpled Polystyrene Microparticles by Dispersion Polymerization.

The design and preparation of hollow nonspherical microparticles are of great significance for their potential applications, but the development of a facile synthetic method using only one production step remains a great challenge. In the current work, a new template-free method based on dispersion polymerization was successfully developed to produce anisotropic hollow polystyrene (PS) microparticles in a single step. In the synthesis, ammonium persulfate (APS) played a critical role in the formation and growth of highly uniform and stable hollow PS microparticles. By varying the concentration of APS and that of the stabilizer used, polyvinylpyrrolidone, we were able to control the average size of the PS particles and their degree of concavity. Based on our results and observations, a plausible mechanism for formation of these unusually shaped PS microparticles was proposed.