Sodium diethyldithiocarbamate as a novel corrosion inhibitor to mitigate corrosion of 2024-T3 aluminum alloy in 3.5 wt% NaCl solution

Efficient removal of NaOl from mineral processing wastewater using Al-electrocoagulation

Sodium oleate (NaOl) is widely used as collector for oxidised ore flotation, and residual NaOl in mineral processing wastewater is a serious threat to mine environment. In this work, the feasibility of electrocoagulation (EC) as an alternative for chemical oxygen demand (COD) removal from NaOl-containing wastewater was demonstrated. Major variables were evaluated to optimise EC, and related mechanisms were proposed to interpret the observations in EC experiments. The initial pH of the wastewater greatly affected the COD removal efficiency, which was likely to be related to the variation of predominant species. When the pH was below 8.93 (original pH), liquid HOl_(l) was the predominant specie, which could be rapidly removed by EC thought charge neutralisation and adsorption. At original pH or higher, Ol^- could react with dissolved Al³⁺ to form insoluble Al(Ol)₃, which was subsequently removed through charge neutralisation and adsorption. The presence of fine mineral particles could reduce repulsion force of the suspended solids and promote flocculation, whereas the presence of water glass had an opposite effect. These results demonstrated that EC can be employed as an effective process to purify NaOl-containing wastewater. This study will contribute to deepening our understanding of EC technology for NaOl removal and provide useful information to researchers in mineral processing industry.

Synthesis and Corrosion Inhibition Potential of Cerium/Tetraethylenepentamine Dithiocarbamate Complex on AA2024-T3 in 3.5% NaCl

In this work, a cerium/tetraethylenepentamine dithiocarbamate complex was synthesized and evaluated for the corrosion inhibition capability on an AA2024-T3 Al alloy in a 3.5% NaCl medium. The synthesized compounds were characterized via spectroscopic techniques. The corrosion inhibition behaviour of the complex was elucidated by electrochemical measurements and surface analysis techniques. Based on electrochemical test results, the corrosion inhibition efficiency of the complex increases with the immersion time of aluminium alloy in the test solution. The corrosion inhibition reaches 96.80% when the aluminium is immersed in a 3.5% NaCl solution containing a corrosion inhibitor for 120 h. The potentiodynamic polarization test results show that the complex acts as a mixed-type corrosion inhibitor and the passive range is widened. The surface analysis methods reveal that the corrosion inhibition ability of the complex originated from the formation of a protective layer on the Al surface. This film is created from the physisorption and chemisorption of cerium ions and organic parts simultaneously released from the complex molecules.

Influence of Rare Earth Samarium/Ytterbium Salt on Electrochemical Corrosion Behavior of Aluminum-Based Anode for Batteries

In this work, effects and mechanism analysis of samarium acetate and ytterbium acetate on enhancing the electrochemical corrosion performance of aluminum-based anode for aluminum-air batteries in 3.5 wt.% NaCl are studied by methods such as weight loss tests, electrochemical measurements, anode galvanostatic discharge tests and microscopic morphology analysis. The results show that samarium acetate and ytterbium acetate are ideal electrolyte additives, and exhibit obvious inhibitory effects on the self-corrosion of 7075 aluminum alloy. The optimal concentration is 200 mg/L. Moreover, corrosion inhibitors mainly reduce the self-corrosion speed of aluminum by suppressing the microcathodic reaction, thereby promoting the improvement of the discharge performance of aluminum-air batteries. Simultaneously, it is found that after mixing samarium acetate and ytterbium acetate in different proportions, the two rare earth salts have a mutual adjustment effect. By adding different rare earth salt components, the battery capacity densities of the anode are improved by 9.6% to 16.3%. Finally, a possible model is presented to illustrate the impact mechanism of different additives on the self-corrosion process and discharge performance of aluminum-air batteries.

Improvement of anti-corrosion performance of an epoxy coating using hybrid UiO-66-NH2/carbon nanotubes nanocomposite

In this study, a porous nanocontainer from UiO-66-NH₂/CNTs nanocomposite with an excellent barrier characteristics was constructed through amine-functionalized Zr-based metal organic framework. The characterization of the prepared nano-materials were performed using different analyses such as FTIR, XRD, SEM, EDS, TEM, and BET and the results proved the successful synthesize of UiO-66-NH₂/CNTs nanocomposite. The corrosion protection performance of the coated panels was investigated by electrochemical impedance spectroscopy (EIS), salt spray, and contact angle measurement. The EIS results revealed that unmodified and UiO-66-NH₂ containing coating in 3.5 wt.% NaCl electrolyte were failed after 45 days but the corrosion was negligible in UiO-66-NH₂/CNTs coating due to high pore resistance values even after 45 days. Salt spray and contact angle measurements confirmed that UiO-66-NH₂/CNTs containing coating acts as an efficient barrier against wet saline environment even at long exposure times. This is attributed to uniform dispersion in the epoxy matrix and formation of a uniform nanocomposite coating.

Evolution and stability of 2-mercaptobenzimidazole inhibitor film upon Al alloy 6061

Organic corrosion inhibitors have become competent alternatives to hazardous chrome conversion coatings due to their rapid adsorption over metal surfaces in corrosive environments. Literature suggests a wide range of organic corrosion inhibitors with high inhibition efficiency, barrier properties, and adsorption mechanisms. However, the long-term durability and protectiveness of an organic inhibitor film need to be understood with in-depth insights on its interaction with heterogenous alloy surfaces like AA6xxx, reduction of galvanic activities and time-resolved degradation due to ionic diffusion. The present article is focused on the time-resolved adsorption and degradation of 2-mercaptobenzimidazole (2-MBI)-induced inhibitor layer/film over AA6061 in 0.1 M NaCl solution. Electrochemical and surface analysis data indicate that the presence of 2-MBI drives the rapid formation of a 20–30 nm thick protective film comprised of constitutional elements of C, S, and N from 2-MBI upon the surface of AA6061 substrate. This film mitigated the corrosion cells associated with nano- and micro-sized Fe and Si-rich intermetallic particles (IMPs) in AA6061. XPS reveals two distinguished bonding states of S and N in the inhibitor film and chemical interactions between 2-MBI and the surface of AA6061. The protective film maintained 65% inhibiting efficiency after 1 day, which progressively degraded due to electrolyte ingress and eventually with a drop in inhibition efficiency down to 21% after 14 days. Inhibitor-induced film over AA6061 reduced the corrosion susceptibility of Fe, and Si-rich IMPs up to 1 day given the subsequent adsorption by S and N heteroatoms. However, this film became thick and defective after 1 day, which undermined its barrier properties against ingress of aggressive ions and facilitated water adsorption.

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Achieving a dendrite-free lithium metal anode through lithiophilic surface modification with sodium diethyldithiocarbamate

Sodium diethyldithiocarbamate (DDTC) monolayer self-assembly on Cu foil can be used to construct a lithiophilic surface modification layer, which can help to achieve a robust and stable SEI and guide homogeneous and dendrite-free Li deposition.

Corrosion mitigation of mild steel in hydrochloric acid solution using grape seed extract

Plant extracts have gained a lot of attention due to their ecofriendly nature for corrosion inhibition. In this study, we examined the inhibition performance of grape seed extract as an eco-environmental inhibitor for mild steel in hydrochloric acid medium. Electrochemical impedance spectroscopy, potentiodynamic polarization, and electrochemical noise techniques were employed to study mild steel's electrochemical behavior in the hydrochloric acid solutions containing grape seed extract. Results depicted that grape seed extract could successfully inhibit the corrosion of mild steel. Besides, water droplet contact angle, field-emission scanning electron microscopy coupled with energy dispersive spectroscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, and atomic force microscopy were utilized to study the surface of mild steel specimens after dipping in acidic solutions. Electrochemical impedance results showed a corrosion efficiency of about 88% in 300 ppm of grape seed extract. Also, results revealed more compact corrosion products with improved integrity in the presence of grape seed, which confirmed electrochemical test results.