ZnO/chitosan nanocomposite was successfully synthesized by in-situ precipitation method. The material was characterized by XRD, FESEM, TEM, FTIR, BET, and TGA. Results show that ZnO/chitosan nanocomposite has spherical shape with the average size of 20–25 nm. BET surface area and the average pore size of ZnO/chitosan nanocomposite are 2.2436 (m2/g) and 12.2 nm, respectively. The material was applied as an adsorbent for congo red removal from aqueous solutions. The congo red adsorption is better described by the Langmuir model (R2=0.996) than by the Freundlich model (R2=0.962). Therefore, it can be presumed that congo red was adsorbed in a single monolayer with the theoretical maximum adsorption capacity of 227.3 (mg/g). This is comparable to other available adsorbents. It can be suggested that ZnO/chitosan nanocomposite could serve as promising adsorbent for congo red in wastewater treatment technology.

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A reaction-transport model in a one-dimensional pit geometry is constructed to study the effect of both cation complexation and concentration-dependent diffusivity on the IR potential drop at steady state and with an anodic limiting current density. When there is no cation complexation, the B value from Galvele's pitting potential equation remains at 59 mV, even when the ionic diffusivities are functions of chloride concentration. However, the B value is found to depend on the anionic charge and the formation of cation complexes. When doubly charged anions are assumed, the B value decreases to 30 mV as predicted from both numerical and analytical results. For the pit dissolution of Fe-17Cr alloy in chloride solution, the B value increases up to 100 mV, in agreement with experiments, assuming dissolved chromium can make cationic chloro-complexes. Such results can be rationalized via the distribution of potential and ionic fluxes at the pit mouth which not only maintain the critical chemistry for pit stability but also sustain the complexation reaction inside the pit.

Polyaniline–mutilwalled carbon nanotube (PANi–MWCNT) nanocomposites were electropolymerized in the presence of sodium dodecyl sulfate (SDS) onto interdigitated platinum-film planar microelectrodes (IDμE). The MWCNTs were first dispersed in SDS solution then mixed with aniline and H2SO4. This mixture was used to electro-synthesize PANi–MWCNT films with potentiostatic method at E = + 0.90 V (versus SCE). The PANi–MWCNT films were characterized by cyclic voltammetry (CV) and scanning electron microscopy (SEM). The results show that the PANi–MWCNT films have a high electroactivity, and a porous and branched structure that can increase the specific surface area for biosensing application. In this work the PANi–MWCNT films were applied for covalent immobilization of glucose oxidase (GOx) via glutaraldehyde agent. The GOx/PANi–MWCNT/IDμE was studied using cyclic voltammetric and chronoamperometric techniques. The effect of several interferences, such as ascorbic acid (AA), uric acid (UA), and acetaminophen (AAP) on the glucosensing at +0.6 V (versus SCE) is not significant. The time required to reach 95% of the maximum steady-state current was less than 5 s. A linear range of the calibration curve for the glucose concentration lies between 1 and 12 mM which is a suitable level in the human body.

This work presents a reaction-transport model for pit propagation coupled with a phase field method to model the moving boundary at the corroding surface. This enables numerical simulations of the simultaneous propagation of multiple pits in close proximity to each other to study the interactions between pits under galvanostatic conditions, with limited applied currents. Results show the formation of lacy covers over pits in stainless steel, which is due to undercutting of the surrounding surface, and reveal the development of other complex morphologies arising from the interaction between neighboring pits; e.g., the growth of “pits within pits” and the evolution of “champion pits.” Such observations are due to the shrinkage of the total active surface to sustain the limited current as pits grow larger. The proposed model can be a valuable tool for studying the evolution of pit morphology in more realistic scenarios when multiple pit initiation sites are present.