scholarly journals Effect of conductive copolymers on scale formation of gypsum

2017 ◽  
Vol 89 (1) ◽  
pp. 153-159 ◽  
Author(s):  
Özlem Dogan ◽  
Cagri Senol Erdemir ◽  
Emel Akyol ◽  
Semra Kirboga ◽  
Mualla Öner
Keyword(s):  
Calcium Sulfate ◽  
Oil And Gas ◽  
Crystallization Rate ◽  
Water Cooling ◽  
Effective Parameters ◽  
Cooling Systems ◽  
Langmuir Adsorption ◽  
Calcium Sulfate Dihydrate ◽  
Vinylphosphonic Acid ◽  
Ft Ir

AbstractThe crystallization of scale forming minerals is an important problem in a number of processes. Calcium sulfate dihydrate (CaSO4·2H2O, gypsum) is the most unwelcome deposit in the production of oil and gas, in water cooling systems and in hydrometallurgical processes. Additives have been used in these processes to prevent the formation and deposition of scaling salts. In this study, the effects of additives on the spontaneuos precipitation of CaSO4·2H2O were investigated in aqueous solutions at 30°C. Conductive copolymers with different vinylphosphonic acid (VPA) contents were used as additives. The degree of inhibition of cystallization was measured as an increase in induction time and the reduction in crystallization rate. The crystallization reactions were interpreted in terms of the Langmuir adsorption isotherm. The cystals were characterized by scanning electron microscope (SEM) and Fourier Transform Infrared Spectroscopy (FT-IR). The VPA content of the copolymer and the supersaturation of the solution were found to be effective parameters on CaSO4·2H2O crystallization.

The Effect of Solvent Polarity on Phase Transformation of Citrogypsum via Hydrothermal Process

2019 ◽  
Vol 803 ◽  
pp. 351-355 ◽  
Author(s):  
Thanakit Sirimahasal ◽  
Yutthana Kalhong ◽  
Lida Simasatitkul ◽  
Siriporn Pranee ◽  
Samitthichai Seeyangnok
Keyword(s):  
Physical Properties ◽  
Calcium Sulfate ◽  
Hydrothermal Process ◽  
Solvent Polarity ◽  
Sem Images ◽  
Crystal Water ◽  
Calcium Sulfate Dihydrate ◽  
Hexagonal Shape ◽  
Ft Ir ◽  
Hexane Solution

Calcium sulfate dihydrate (CaSO4•2H2O, CSD), gypsum is a by-product in the production of citric acid (citryogypsum). This by-product could neither be exploited nor distributed as a reactant because of its physical properties including those that are not equivalent to natural gypsum. Moreover, the mentioned citrogypsum has been continually increasing environmental problems. Therefore, this research aims at how to recycle gypsum that is synthesized by hydrothermal method at 95oC for 7 hrs under the atmospheric pressure via different solutions (MeOH, EtOH, PrOH, BuOH and Hexane). In order to produce alpha-calcium sulfate hemihydrate (α-CaSO4•0.5H2O, α-CSH) with improved physical properties that will be used for different industries. FT-IR reveals the chemical composition of crystal and the adsorption of methyl group on the surface. Besides, TGA thermogram shows the theoretical crystal water content of CSD and α-CSH 20.9 wt% and 6.2 wt% respectively. The DSC thermogram, shows that endothermic peaks at 151.2 oC and 168.5 oC. There were two steps of loss at 1.5 and 0.5 water molecule respectively. With SEM images of crystal shows the plate-like shape of citrogypsum, while α-CSH shows the hexagonal shape excluding hexane solution. Of all the results, the polarity of solution has an impact on the transition of CSD to α-CSH under this condition.

The Kinetics and Mechanism of Formation of Calcium Sulfate Scale Minerals—The Influence of Inhibitors

CORROSION ◽  
1979 ◽  
Vol 35 (7) ◽  
pp. 304-308 ◽  
Author(s):  
GEORGE H. NANCOLLAS ◽  
WESLEY WHITE ◽  
FELIX TSAI ◽  
LARRY MAS LOW
Keyword(s):  
Calcium Sulfate ◽  
Mechanism Of Formation ◽  
Seeded Growth ◽  
Langmuir Adsorption ◽  
Calcium Sulfate Dihydrate ◽  
Calcium Sulfate Scale ◽  
Rate Of Reaction ◽  
Growth Method ◽  
Kinetics Of ◽  
Calcium Sulfate Hemihydrate

Abstract A seeded growth method has been used to study the kinetics of crystallization of calcium sulfate dihydrate at various temperatures and at ionic strengths up to 0.6M. Under all conditions, the rate of reaction is proportional to the square of the relative supersaturation and is controlled by a surface process. The same kinetics are applicable for the growth of calcium sulfate hemihydrate at temperatures above 110 C. The organic phosphonates effectively retard scale formation, and diethylenetriaminepenta (methylenephosphonic acid), when present at a concentration as low as 10−7M, completely inhibits the growth of calicum sulfate hemihydrate at 120 C. By assuming that the inhibitor molecules are adsorbed on growth sites on the surface of the crystals, the inhibition can be interpreted in terms of a simple Langmuir adsorption isotherm.

Preparation of Calcium Sulfate Anhydrate Whisker and a Primary Investigation of its Arsenic Removal Performance

2013 ◽  
Vol 690-693 ◽  
pp. 1013-1019
Author(s):  
Xiao Juan Chen ◽  
Liu Chun Yang ◽  
Jun Feng Zhang ◽  
Yan Huang
Keyword(s):  
Calcium Sulfate ◽  
Arsenic Removal ◽  
Removal Rate ◽  
Optical Microscope ◽  
Alkaline Condition ◽  
Crystal Water ◽  
Arsenic Uptake ◽  
Ft Ir ◽  
High Removal Rate ◽  
Calcium Sulfate Whisker

Calcium sulfate whisker (CSW) was prepared through the method of cooling recrystallization. In an attempt to develop its new application in environmental protection, we investigated the effect of calcination on the material properties and arsenic uptake performance of calcium sulfate whisker anhydrate (CSAW), which was obtained from CSW calcined at 600 °C for 2 h. Moreover, XRD, SEM, optical microscope, and FT-IR were used to characterize CSW samples. It was found that calcination played an important role in the whisker structure through changing the content of crystal water and the morphology. The CSAW material exhibited a high removal rate of As3+/As5+under strongly alkaline condition.

scholarly journals Newly Synthesized N-Substituted Thiosemicarbazone as a Potential Corrosion Inhibitor for Mild Steel in 1 M HCl

2019 ◽  
Vol 7 (4.14) ◽  
pp. 168
Author(s):  
N Z. Nor Hashim ◽  
K Kassim ◽  
F H. Zaidon
Keyword(s):  
Mild Steel ◽  
Corrosion Inhibitor ◽  
Potentiodynamic Polarization ◽  
Corrosion Inhibitors ◽  
Inhibition Efficiency ◽  
Electrochemical Impedance ◽  
Langmuir Adsorption ◽  
Before And After ◽  
Ft Ir ◽  
L1 And L2

Two N-substituted thiosemicarbazone derivatives namely as 2-(4-chlorobenzylidene)-N-phenylhydrazinecarbothioamide and 2-benzylidene-N-phenylhydrazinecarbothioamide (L1 and L2, respectively) have been tested as corrosion inhibitors on mild steel in 1 M HCl. The ligands were synthesized and investigated using potentiodynamic polarization (PD) and electrochemical impedance spectroscopy (EIS).  The obtained results indicated that inhibition efficiency, (IE, %) L1 increased with increasing inhibitor concentrations which behaved as a good corrosion inhibitor compared to L2. The synthesized ligands were successfully characterized by melting point, elemental analysis (C, H, N, and S), Fourier-transform infrared spectroscopy (FT-IR) and NMR (1H and 13C) spectroscopy. The excellent inhibition effectiveness for both compounds on mild steel before and after immersion in 1 M HCl solution containing 40 ppm of L1 and L2 were also verified by scanning electron microscope (SEM). Based on potentiodynamic polarization results, it can be concluded that all investigated compounds are mixed-type inhibitors and obey the Langmuir adsorption isotherm. 

scholarly journals Inhibition of Pipeline Steel Corrosion in 0.5 M H2SO4 Using Cotyledon of Chrysophyllum Albidum

2020 ◽  
Vol 24 (4) ◽  
pp. 691-697
Author(s):  
E.P. Othaki ◽  
N.C. Ngobiri
Keyword(s):  
Corrosion Inhibitors ◽  
Inhibition Efficiency ◽  
Adsorption Process ◽  
Pipeline Steel ◽  
Steel Corrosion ◽  
Langmuir Adsorption ◽  
Extract Concentration ◽  
Ir Studies ◽  
Ft Ir ◽  
As Adsorption

The corrosion inhibition characteristics of Chrysophyllum albidum cotyledon extract was studied as a green and sustainable corrosion inhibitors for pipeline steel in acidic environment attemperatures, 303,313 and 323K using gravimetric technique.The results obtained showed that the inhibition efficiency increased with increase in extract concentration but decrease with increase in temperature. The extract attained an inhibition efficiency of 94 % with 5 g/L at 303 K and 52.2 % with 1 g/L at 333K. Also increase in concentration of the extract lead to increase in activation energydepicting an exothermic process.Fourier transform infrared spectroscopy (FT-IR) studies showed the mode of inhibition as adsorption of phytochemicals from the extract on pipeline steel surface. Langmuir adsorption isotherm best fitted into the adsorption process which is spontaneous and physical. Keywords: Chrysophyllum albidum, Pipeline steel, Inhibition, Adsorption.

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