Three novel dendritic chitosan derivatives for inhibiting acid corrosion of petroleum pipelines

In the process of exploration and development of oil and gas fields, the acidic environment of oil reservoir, production and transport processes cause corrosion of pipelines and equipment, resulting in huge economic losses and production safety risks. Corrosion inhibitors were widely used in oil industry because of simple operation process and economical. In this study, three environmentally friendly corrosion inhibitors were synthesized based on the natural polysaccharide chitosan. Corrosion inhibition of three dendritic chitosan derivatives (We name them BH, CH and DH) on mild steel in 1 mol/L HCl solution with natural ventilation system was evaluated by weight loss experiment, electrochemical analysis and surface morphology characterization. The experimental results showed that when the three dendritic chitosan derivatives added in the corrosive medium were 500 mg L^(−1), the corrosion inhibition efficiencies were all more than 80%. Based on quantum chemical calculation, inhibition mechanisms of three dendritic chitosan derivatives were investigated according to molecular structures. The results showed that the benzene ring, Schiff base and N atom contained in the molecule were the active centers of electron exchange, which were more likely to form a film on the carbon steel surface, thereby slowing or inhibiting corrosion. The results also predicted the corrosion inhibition effect BH > DH > CH, which was consistent with the experimental conclusion.

Corrosion Inhibition of Carbon Steel in Hot Hydrochloric Acid Solutions

The dissolution of carbon steel in 5% HCl in the temperature range of 30~90℃ was inhibited by two organic compounds having the general formula: ClR NH2(CH2)n NH2 RCl where R is a benzyl group. The behaviour of these inhibitors in acidic medium were investigated using weight loss method, open circuit potential and linear polarization technique. These inhibitors provided satisfactory corrosion inhibition for carbon steel in hydrochloric acid solutions even at higher temperature and acid concentration (10%). The electrochemical results showed that the polarization resistance (Rp) values increased with increasing inhibitor concentration, also the corrosion current decreased and a higher inhibition efficiency was obtained. The protective properties of these two organic inhibitors were attributed to the chemisorption mechanism

Cocos nucifera L.water as green corrosion inhibitor for acid corrosion of aluminium in HCl solution

The ability of Cocos nucifera L.water（CW） as non-toxic corrosion inhibitor for acid corrosion of aluminium in 0.5 mol/L HCl has been studied using chemical technique.CW shows significant inhibition as corrosion inhibitor,with 93%efficiency at the highest concentration of the inhibitor.The inhibitive action is attributed to the adsorption of the inhibitor molecules on metal surface following Langmuir adsorption isotherm.

Safety of the long-term use of proton pump inhibitors

The proton pump inhibitors (PPIs) as a class are remarkably safe and effective for persons with peptic ulcer disorders. Serious adverse events are extremely rare for PPIs, with case reports of interstitial nephritis with omeprazole, hepatitis with omeprazole and lansoprazole, and disputed visual disturbances with pantoprazole and omeprazole. PPI use is associated with the development of fundic gland polyps (FGP); stopping PPIs is associated with regression of FGP. In the absence of Helicobacter pylori infection, the long-term use of PPIs has not been convincingly proven to cause or be associated with the progression of pre-existing chronic gastritis or gastric atrophy or intestinal metaplasia. Mild/modest hypergastrinemia is a physiological response to the reduction in gastric acid secretion due to any cause. The long-term use of PPIs has not been convincingly proven to cause enterochromaff in-like cell hyperplasia or carcinoid tumors. PPIs increase the risk of community acquired pneumonia, but not of hospital acquired (nosocomial) pneumonia. There is no data to support particular care in prescribing PPI therapy due to concerns about risk of hip fracture with the long-termuse of PPIs. Long-term use of PPIs does not lead to vitamin B12 def iciencies, except possibly in the elderly, or in persons with Zollinger-Ellison Syndrome who are on high doses of PPI for prolonged periods of time. There is no convincingly proven data that PPIs increase the risk of Clostridium difficile-associated diarrhea in persons in the community. The discontinuation of PPIs may result in rebound symptoms requiring further and even continuous PPI use for suppression of symptoms. As with all medications, the key is to use PPIs only when clearly indicated, and to reassess continued use so that long-term therapy is used judiciously. Thus, in summary, the PPIs are a safe class of medications to use longterm in persons in whom there is a clear need for the maintenance of extensive acid inhibition.

Experimental and Quantum Studies on Adsorption and Corrosion Inhibition Effect on Mild Steel in Hydrochloric Acid by Thiophene Derivatives

The inhibition effect of synthesized diethyl 3,4-bis（4-methoxybenzylideneamino） thieno[2,3-b] thiophene-2,5- dicarboxylate （Inh I） and diethyl 3,4-bis（benzylideneamino） thieno[2,3-b] thiophene-2,5-dicarboxylate （Inh II）, on cor- rosion of mild steel in 15% HC1 solution was investigated using weight loss measurements, electrochemical polarization, and electrochemical impedance spectroscopy techniques. The experimental results show that the inhibition efficiency of studied inhibitors increased with the increase of inhibitors concentration but decreased with the increase of temperature. Corrosion inhibition efficiencies of 94.5% and 92.1% were obtained with 250 ppm of Inh I and Inh II at 303 K, respectively. The potentiodynamic polarization measurements indicate that the studied inhibitors act as mixed inhibitor. The thermodynamic parameters of the corrosion and adsorption processes were calculated and evaluated. The adsorption of these inhibitors was found to obey Langmuir adsorption isotherm. Scanning electron microscopy was used to characterize the surface morphology of the mild steel specimens in presence and absence of inhibitors. The mechanism of the inhibition process was discussed in the light of the chemical structure and quantum-chemical calculations of the investigated inhibitors.

油溶性羧酸铜与二烷基二硫代磷酸锌的抗腐蚀效果

通过Cu片腐蚀试验、红外光谱和XPS扫描分析 ,对油溶性羧酸铜铜剂和二烷基二硫代磷酸锌 (T2 0 2 )的抗腐蚀性能进行了研究 .铜剂与T2 0 2 分别具有良好的抗腐蚀特性 ,两者复合后随着铜剂含量的增加抗腐蚀效果变差 .添加剂之间相互作用使元素S的活性增强 。

Bile acids control inflammation and metabolic disorder through inhibition of NLRP3 inflammasome

With the support by the National Natural Science Foundation of China,the research team led by Prof.Wang Di(王迪)at the Immuno metabolism Lab,Institute of Immunology,Zhejiang University School of Medicine,uncovered the mystery of Bile Acids control inflammation and metabolic disorder,which was published in Immunity(2016,45:802—816)).

An Eco-Friendly High-Effective Scale Inhibitor for High Salt Brine

Now the mining of high salt underground brine has been an important aspect of salt lake mining,which is the necessary support to the development of national economy.With the change of underground geological

Impact of undissociated volatile fatty acids on acidogenesis in a two-phase anaerobic system

This study investigated the degradation and production of volatile fatty acids（VFAs）in the acidogenic phase reactor of a two-phase anaerobic system.20 mmol/L bromoethanesulfonic acid（BESA）was used to inhibit acidogenic methanogens（which were present in the acidogenic phase reactor）from degrading VFAs.The impact of undissociated volatile fatty acids（un VFAs）on＂net＂VFAs production in the acidogenic phase reactor was then evaluated,with the exclusion of concurrent VFAs degradation.＂Net＂VFAs production from glucose degradation was partially inhibited at high un VFAs concentrations,with 59%,37% and 60% reduction in production rates at 2190 mg chemical oxygen demand（COD）/L undissociated acetic acid（un HAc）,2130 mg COD/L undissociated propionic acid（un HPr）and 2280 mg COD/L undissociated n-butyric acid（un HBu）,respectively.The profile of VFAs produced further indicated that while an un VFA can primarily affect its own formation,there were also un VFAs that affected the formation of other VFAs.

1,4-Bis(2-nitrobenzylidene) thiosemicarbazide as Effective Corrosion Inhibitor for Mild Steel

The inhibition efficiency of 1,4-bis （2-nitrobenzylidene） thiosemicarbazide （BBTS） on the corrosion of mild steel in 1 mol/L HCI was investigated by potentiodynamic polarization and electrochemical impedance methods. Inhibition efficiency （IE）, corrosion rate and surface coverage were evaluated at different concentrations of BBTS. The results of the investigation showed that this compound had good inhibiting properties for mild steel corrosion in hydrochloric acid and BBTS was a mixed-type inhibitor. BBTS chemisorbed at the electrode surface obeyed Langmuir adsorption isotherm and formed a stable surface complex on the mild steel surface. The synergistic effect of halide ion in acid solution suggested a co-adsorption of BBTS inhibitor by the adsorbed iodide ion.

The effect of salinity on waste activated sludge alkaline fermentation and kinetic analysis

The effect of salinity on sludge alkaline fermentation at low temperature（20°C） was investigated, and a kinetic analysis was performed. Different doses of sodium chloride（Na Cl, 0–25 g/L） were added into the fermentation system. The batch-mode results showed that the soluble chemical oxygen demand（SCOD） increased with salinity. The hydrolysate（soluble protein, polysaccharide） and the acidification products（short chain fatty acids（SCFAs）, NH＋4–N, and PO_4^（3-）–P） increased with salinity initially, but slightly declined respectively at higher level salinity（20 g/L or 20–25 g/L）. However, the hydrolytic acidification performance increased in the presence of salt compared to that without salt.Furthermore, the results of Haldane inhibition kinetics analysis showed that the salt enhanced the hydrolysis rate of particulate organic matter from sludge particulate and the specific utilization of hydrolysate, and decreased the specific utilization of SCFAs. Pearson correlation coefficient analysis indicated that the importance of polysaccharide on the accumulation of SCFAs was reduced with salt addition, but the importance of protein and NH＋4–N on SCFA accumulation was increased.

Development of bis-thiobarbiturates as successful urease inhibitors and their molecular modeling studies

Bis-thiobarbiturate derivatives 1-15 have been synthesized, characterized by 1HNMR and El-MS and screened for urease inhibition. All compounds showed various degree of urease inhibitory activity with iC50 values ranging 7.45 ± 0.12 - 74.24 ± 0.81 μmol/L while the standard thiourea behaved normally （ICso = 21.10 ±0.12）. Compounds I （IC50= 7.45 ± 0.12 ]μmol/L）, 9 （IC50 =18,17 ± 1.03 bmol/L） and 13 （IC50= 8.61 ± 0.45 bmol/L） showed excellent urease inhibitory activity in the series. Molecular modeling studies were performed to understand the binding site with the bimetallic nickel center of the enzyme. Structure-activity relationship has also been established for these compounds. This study identified bis- thiobarbiturate as a novel class of urease inhibitors.