Comprehensive study on surfactant role on silver nanoparticles (NPs) prepared via modified Tollens process (original) (raw)
Related papers
Synthesis and characterization of silver nanospheres in mixed surfactant solution
2014
The synthesis and characterization of silver (Ag) nanorods through the Turkevich method in aqueous sodium dodecylsulfate (SDS) solutions have been studied in this work. The results have shown that the shape of Ag nanoparticles closely correlated with SDS concentration in the synthesis process. With high SDS concentrations, the majority of the synthesized Ag nanoparticles appeared in the form of nanorods; with low SDS concentrations, the Ag nanoparticles were spherical. This observation might be attributed to that the Ag nanoparticles grew up in SDS micelles and precipitated in the same shape of the micelles, because surfactant micelles were of cylinders in high concentrations and of spheres in low concentrations.
Studies on the kinetics of growth of silver nanoparticles in different surfactant solutions
Colloids and Surfaces B: Biointerfaces, 2009
Silver nanoparticles were prepared in aqueous silver nitrate solution using hydrazine as reducing agents in presence of two ionic surfactants (cetyltrimethylammonium bromide; CTAB and sodium dodecyl sulfate; SDS) and one non-ionic surfactant (Triton X-100). The reaction rate was determined spectrophotometrically. The nature of the head group of these surfactants is responsible for the formation of stable, yellow and transparent silver sol. For a certain reaction time, i.e., 20 min, the absorbance of reaction mixture first increased until it reached a maximum, then decreased with [hydrazine]. The reaction follows first-order kinetics with respect to each in [hydrazine] and [Ag + ]. The results suggest formation of a complex between silver(I) and hydrazine, decomposes in a rate-determining step, leading in the formation of a free radical, which again reacts with the silver(I) in a subsequent fast step to yield the products. The transmission electron microscopic (TEM) images show that CTAB stabilized silver nanoparticles are spherical and of uniform particle size, and the average particle size is about 15 nm.
Formation and characterization of surfactant stabilized silver nanoparticles: A kinetic study
Colloids and Surfaces B: Biointerfaces, 2008
Kinetic data for the silver nitrate-ascorbic acid redox system in presence of three surfactants (cationic, anionic and nonionic) are reported. Conventional spectrophotometric method was used to monitor the formation of surfactant stabilized nanosize silver particles during the reduction of silver nitrate by ascorbic acid. The size of the particles was determined with the help of transmission electron microscope. It was found that formation of stable perfect transparent silver sol and size of the particles depend upon the nature of the head group of the surfactants, i.e., cetyltrimethylammonium bromide (CTAB), sodium dodecyl sulphate (SDS) and Triton X-100. The silver nanoparticles are spherical and of uniform particle size, and the average particle size is about 10 and 50 nm, respectively, for SDS and CTAB. For a certain reaction time, i.e., 30 min, the absorbance of reaction mixture first increased until it reached a maximum, then decreased with [ascorbic acid]. The reaction follows a fractional-order kinetics with respect to [ascorbic acid] in presence of CTAB. On the basis of various observations, the most plausible mechanism is proposed for the formation of silver nanoparticles.
Chemical Engineering and Processing: Process Intensification, 2012
In this work an attempt was made to intensify the process of nanoparticles synthesis in microreactor. Main objective of the work was to investigate the intensification of silver nanoparticles synthesis using surfactants and to study the effect of associated process parameters in microreactor such as concentration and flow rate of precursor. Reduction reaction was carried out using silver nitrate and sodium borohydride. Two surfactants namely sodium dodecyl sulfate (SDS) and N-cetyl N,N,N,trimethyl ammonium bromide (CTAB) were used to evaluate the effect on particle size by controlling nucleation and growth mechanism. Results of microreactor synthesis were compared with batch process. Optimum parameters such as flow rates, concentrations of reactants/surfactants were determined to obtain nanosize silver colloidal particles in continuous microreactor. Results show that use of 0.02 g/mL SDS with 1 mL/min (0.001 M) AgNO 3 and 3 mL/min (0.003 M) NaBH 4 flow rate shows minimum particle size of 4.8 nm. From residence time distribution (RTD) data, it is found that the Pe ax number was highest 0.39 at Re number 67 (flow rate of 7 mL/min), which signifies the less axial dispersion. The increase in the particle size with an increase in the CTAB loading is due to the agglomeration effect that cationic CTAB, which has positive charge on head, leads to aggregation. SDS favors the reduction in particle size of silver nanoparticle.
2016
Interaction between the anionic and nonionic surfactant at bulk and air/water interface has been studied. The synergistic interaction between surfactants was found in both in bulk solution as well as the interface. The different physicochemical parameters of the free surfactant monomers up to the point of their critical micelle concentration (cmc) have been evaluated and discussed in detail. The synergistic interactions have been analyzed using various theoretical models reported i.e., Clint, Rubingh, Maeda and Rosen models. The spectrophotometric and structural analyses have been achieved for the formation of silver nanoparticles using sodium borohydride as reducing agents and pure as well as mixed surfactant systems as capping agents. Antimicrobial activities of the synthesized nanoparticles were performed against both Gram-negative (P. aeruginosa and Klebsiella Pneumonia) and Gram-positive (Micrococcus luteus) bacteria.
Water based simple synthesis of re-dispersible silver nano-particles P.K.
Successful experiments with tri-sodium citrate as initial surfactant-cum-reducing agent followed by a secondary reducing agent i.e. sodium formaldehyde sulphoxylate (SFS) to silver nitrate were performed which established a clear large-scale method for the preparation of silver nano- powder of particle size of less than 50 nm. The citrate ions also create hydrophilic capping to in-situ generated zero-valent silver, thus leading to surfactant capped particles. Partial re-dispersion of such nano-powder in aqueous medium leads to colloidal silver which can be loaded in water friendly polymers such as polyvinyl alcohol (PVA) and polyvinyl pyrrolidone (PVP). UV–Visible absorption band at about 275 and 400 nm of colloidal silver in water can be retained even after loading in polymer. Transmission electron microscopy (TEM) of the colloidal solution showed a particle of the size b30 nm. Particle size distribution by dynamic light scattering technique (DLS) showed that the particles are in the range of 10– 40 nm. The elemental composition was studied by energy dispersive analysis of X-rays (EDS
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2014
Metal nanoparticles possess unique characteristics which differ from bulk properties [1,2]. Metal nanoparticles are glamorous materials for catalysis with selectivity and specificity. Metal nanoparticles have received remarkable recognition due to their unique features [3,4]. Among various metal particles, copper nanoparticles (CuNPs) posses applications in modern technologies such as metal injection moulding, ceramics, electronics, thin films, biology and medicine. Low-cost of CuNPs have received much attention when compared with costly gold or silver [5,6] nanoparticles. Copper nanoparticles (CuNPs) have been used in non-rigid electronics [7-10], catalysis [11-14], light emitting diodes (LED) [10] and in biology [15,16] and medicine. Nevertheless, the synthesis of CuNPs is more difficult beneath atmospheric contexts in collation to virtuous metals like gold and silver as copper is susceptible for easy oxidation. Different tactics [17-26] have been used to conquer this problem. The preparation procedure in thermal reduction method is straight forward and the dimension and configuration of CuNPs can be easily tracked. In contrast to traditional techniques, it is much speedy, unstained and less expensive.