Effect of operating parameters on dye wastewater treatment using Prosopis cineraria and kinetic modeling

Rajamohan Natarajan,Rajasimman Manivasagan 대한환경공학회 2020 Environmental Engineering Research Vol.25 No.5

Textile dye effluent treatment was investigated using a novel biosorbent synthesized from Prosopis cineraria. The influence of operating variables, namely initial COD of the effluent (352-1,303 ㎎/L) and adsorbent dosage (0.25-4.0 g/L) on the removal efficiency was studied. The results of the biosorption experiments indicated that the equilibrium COD removal efficiency attained was 68% and COD uptake achieved was 90.52 ㎎/g at an optimal sorbent dose (2.0 g/L). Pseudo second order model fitted well to the experimental data and the rate constant was estimated as 0.098 x 10<SUP>-5</SUP> g /(㎎ min) .Chemisorption was identified as the removal mechanism involved. Power function model represented the kinetic data in selected range of COD and kinetic constants were estimated. XRF analysis of the biosorbent confirmed the presence of potassium oxide and calcium oxide as the two major components.

Fe3O4-Ag2WO4: facile synthesis, characterization and visible light assisted photocatalytic activity

Rajamohan, S.,Kumaravel, V.,Muthuramalingam, R.,Ayyadurai, S.,Abdel-Wahab, A.,SubKwak, B.,Kang, M.,Sreekantan, S. Royal Society of Chemistry 2017 NEW JOURNAL OF CHEMISTRY Vol.41 No.20

Corrosion inhibition of aluminum under basic conditions using Medicago sativa L. extract - thermodynamic studies

Rajamohan Natarajan,Fatma Al Shibli 한국화학공학회 2021 Korean Journal of Chemical Engineering Vol.38 No.9

In this research, corrosion inhibitors were synthesized using locally available biomass, alfalfa plant. The inhibitor performance was evaluated at different operating conditions and the effect of process variables, namely inhibitor concentration (1-5%v/v), operating temperature (308.15-328.15 K) and method of extraction (alcohol and aqueous) were studied. The corrosion rate of aluminum decreased with increase in inhibitor concentration and the best result attained was 3.7mg cm2 h1 with 5%v/v AALE and 308.15 K. The increase in temperature resulted in the decrease in inhibition efficiency, which could be related to detachment of inhibitors at elevated temperatures. The Langmuir adsorption Isotherm fitted well to the corrosion experiment data (R2>0.990) and thermodynamic parameters were calculated. The value of separation factor (0<RL<1) confirmed the favorable adsorption of corrosion inhibitor on the metal surface. Surface characterization of the green inhibitor using scanning electron microscopy was conducted to understand the morphology and FTIR spectrum was used to identify the main functional groups for Alfalfa extracts. The alcoholic extract possessed comparatively higher number of surface-active groups and produced better performance than aqueous extract. Arrhenius plots were employed to determine the activation energy. Tafel plot was used to determine theoretical corrosion current and potential. Electrochemical impedance spectroscopy inhibition efficiency was found to be 90.91% with 5% AALE.

Trihalomethane formation potential of drinking water sources in a rural location

Rajamohan, R.,Ebenezer, Vinitha,Rajesh, Puspalata,Venugopalan, V.P.,Natesan, Usha,Murugesan, V.,Narasimhan, S.V. Techno-Press 2012 Advances in environmental research Vol.1 No.3

Trihalomethanes, produced as a result of chlorination of drinking water, are considered a potential health hazard. The trihalomethane formation potential (THMFP) of a raw water source may indicate the maximum trihalomethanes (THMs) that are likely to be produced when chlorine reacts with natural organic matter (NOM) present in the water. A study was conducted to evaluate the THMFP in seven different drinking water sources in the vicinity of Kalpakkam, a rural township, on the east coast of India. Water from seven stations were analysed for THMFP. THMFP was compared with surrogate parameters such as dissolved organic carbon (DOC), ultraviolet absorbance ($UV_{254}$) and bromide. The data showed that THMFP was high in water from open wells as compared to closed bore wells, possibly due to more photosynthetic activity. Proximity to sea, and consequently the levels of bromide, was an important factor that influenced THM formation. THM surrogate parameters showed good correlation with THMFP.

Molecular encapsulation of nortriptyline in the β-cyclodextrin cavity: In-vitro cytotoxic potential against MCF-7 cell line

Rajamohan Rajaram,Viswalingam Muthusamy,이용록,Prabu Samikannu,Sivakumar Krishnamoorthy 한국화학공학회 2023 Korean Journal of Chemical Engineering Vol.40 No.7

In the liquid state, UV-visible and fluorescence spectroscopy was used to examine the inclusion complexes of nortriptyline (NP) and β-cyclodextrin (β-CD). The degree of inclusion complexation causes NP’s absorbance and fluorescence intensity to be significantly increased during interaction with β-CD. The binding constant was determined by UV-VIS and fluorescence spectroscopy, and the results indicated a 1:1 stoichiometry for the inclusion complex at 303 K. Complexation is a spontaneous and exothermic process, as determined by Gibbs’s free energy change. To produce solid inclusion complexes (ICs), mixing and co-precipitation were used, which were then characterized using Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM), X-ray powder diffraction (XRD), and thermogravimetric analysis/differential scanning calorimetry (TGA/DSC). According to molecular docking studies, the aromatic ring of the NP does not penetrate the secondary hydroxyl rim of the β-CD cavity, but the aliphatic part of the NP trapped in the cavity is more thermodynamically advantageous. NP and NP: β-CD-ICs were screened for in vitro cytotoxicity on Michigan Cancer Foundation-7 (MCF-7) cell line using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay, and the results showed that the cytotoxicity was not affected by creating an ICs.

Beneficial Effects of Coconut Water Feeding on Lipid Metabolism in Cholesterol-Fed Rats

T. Rajamohan,V.G. Sandhya 한국식품영양과학회 2006 Journal of medicinal food Vol.9 No.3

The purpose of this study was to determine the effect of coconut water feeding in cholesterol-fed rats. Maleterol feeding caused a marked increase in total cholesterol, very low-density lipoprotein (VLDL). low-density lipoprotein(LDL) cholesterol, and triglycerides in serum. Administration of coconut water counteracts the increase in total cholesterol,VLDL. LDL cholesterol, and triglycerides, while high-density lipoprotein cholesterol was higher. Lipid levels in the tissuesviz. liver, heart, kidney, and aorta were markedly decreased in cholesterol-fed rats supplemented with coconut water. Feed-ing coconut water resulted in increased activities of 3-hydroxy-3-methylglutaryl-CoA reductase in liver, lipoprotein lipase inheart and adipose tissue, and plasma lecithin:cholesterol acyl transferase, while lipogenic enzymes showed decreased activites.An increased rate of cholesterol conversion to bile acid and an increased excretion of bile acids and neutral sterols were ob-served in rats fed coconut water. Histopathological studies of liver and aorta revealed much less fatty accumulation in thesetissues in cholesterol-fed rats supplemented with coconut water. Feeding coconut water resulted in increased plasma L-argi-nine content, urinary nitrite level, and nitric oxide synthase activity. These results indicate that both tender and mature co-conut water has beneficial effects on serum and tissue lipid parameters in rats fed cholesterol-containing diet.

Dynamic characterization of a CNT reinforced hybrid uniform and non-uniform composite plates

Jakkamputi Lakshmipathi,Rajamohan Vasudevan 국제구조공학회 2019 Steel and Composite Structures, An International J Vol.30 No.1

In the present study, the various dynamic properties of MWCNT embedded fiber reinforced polymer uniform and tapered composite (MWCNT-FRP) plates are investigated. Various configurations of a tapered composite plate with ply-drop off and uniform composite plate have been considered for the development of the finite element formulation and experimental investigations. First order shear deformation theory (FSDT) has been used to derive the kinetic and potential energy equations of the hybrid composite plates by including the effect of rotary inertia, shear deformation and non-uniformity in thickness of the plate. The governing equations of motion of FRP composite plates without and with MWCNT reinforcement are derived by considering a nine- node rectangular element with five degrees of freedom (DOF) at each node. The effectiveness of the developed finite element formulation has been demonstrated by comparing the natural frequencies and damping ratio of FRP composite plates without and with MWCNT reinforcement obtained experimentally. Various parametric studies are also performed to study the effect of CNT volume fraction and CNT aspect ratio of the composite plate on the natural frequencies of different configurations of CNT reinforced hybrid composite plates. Further the forced vibration analysis is performed to compare the dynamic response of the various configurations of MWCNT-GFRP composite plate with GFRP composite plate under harmonic excitations. It was observed that the fundamental natural frequency and damping ratio of the GFRP composite plate increase approximately 8% and 37% respectively with 0.5wt% reinforcement of MWCNT under CFCF boundary condition. The natural frequencies of MWCNT-GFRP hybrid composite plates tend to decrease with the increase of MWCNT volume fraction beyond 2% due to agglomeration of CNT‘s. It is also observed that the aspect ratio of the CNT has negligible effect on the improvement of dynamics properties due to randomly orientation of CNT‘s.

Investigation on interlaminar shear stresses in laminated composite beam under thermal and mechanical loading

Nagaraj Murugesan,Vasudevan Rajamohan 국제구조공학회 2015 Steel and Composite Structures, An International J Vol.18 No.3

In the present study, the combined effects of thermal and mechanical loadings on the interlaminar shear stresses of both moderately thin and thick composite laminated beams are numerically analyzed. The finite element modelling of laminated composite beams and analysis of interlaminar stresses are performed using the commercially available software package MSC NASTRAN/PATRAN. The validity of the finite element analysis (FEA) is demonstrated by comparing the experimental test results obtained due to mechanical loadings under the influence of thermal environment with those derived using the present FEA. Various parametric studies are also performed to investigate the effect of thermal loading on interlaminar stresses generated in symmetric, anti-symmetric, asymmetric, unidirectional, cross-ply, and balanced composite laminated beams of different stacking sequences with identical mechanical loadings and various boundary conditions. It is shown that the elevated thermal environment lead to higher interlaminar shear stresses varying with the stacking sequence, length to thickness ratio, ply orientations under identical mechanical loading and boundary conditions of the composite laminated beams. It is realized that the magnitude of the interlaminar stresses along xz plane is always much higher than those of along yz plane irrespective of the ply-orientation, length to thickness ratios and boundary conditions of the composite laminated beams. It is also observed that the effect of thermal environment on the interlaminar shear stresses in carbon-epoxy fiber reinforced composite laminated beams are increasing in the order of symmetric cross-ply laminate, unidirectional laminate, asymmetric cross-ply laminate and anti-symmetric laminate. The interlaminar shear stresses are higher in thinner composite laminated beams compared to that in thicker composite laminated beams under all environmental temperatures irrespective of the laminate stacking sequence, ply-orientation and boundary conditions.

Analgesic activity of flavonoids isolated from Persicaria glabra (wild)

Manivannan Rajamanickam,Shopna Rajamohan 경희대학교 융합한의과학연구소 2020 Oriental Pharmacy and Experimental Medicine Vol.20 No.1

The present experimental study conducted to determine the four flavonoids (1–4) isolated from extracts of Persicaria glabra (Polygonaceae) and was tested for its potential central and peripheral analgesic activity. All animals were lowered on a hot plate (55 ± 0.5 °C), the observations were made before and after administration of respective drugs at 30, 60, and at the end of 90 min. In writhing method, acetic acid is administered intraperitoneal to the experimental animals to create pain sensation. The writhing movements were observed and counted for 30 min after acetic acid administration. The results showed that the compound quercetin (1) and its glycosides (3) at a dose of 100 and 200 mg/kg body weight significant analgesic activity (P < 0.05) in both central and peripheral models of analgesia used. The same doses, compounds 2 and 4 did not show any analgesic effects. Among them, quercetin (1) was the most potent in both models tested. Also due to structural difference of four compounds, a number of hydroxyl groups, substitution of –OCH3 and glycosylation, they will exhibit different analgesic responses. The P. glabra leaf extracts containing mixture of quercetin, isorhamnetin and their glycosides were effective in both the central and peripheral models of pain.

Microbial fuel cell for oilfield produced water treatment and reuse: Modelling and process optimization

Majid Mohammadi,Mehdi Sedighi,Rajamohan Natarajan,Sedky Hassan Aly Hassan,Mostafa Ghasemi 한국화학공학회 2021 Korean Journal of Chemical Engineering Vol.38 No.1

Oilfield produced water is one of the vast amounts of wastewater that pollute the environment and cause serious problems. In this study, the produced water was treated in a microbial fuel cell (MFC), and response surface methodology and central composite design (RSM/CCD) were used as powerful tools to optimize the process. The results of two separate parameters of sulfonated poly ether ether ketone (SPEEK) as well as nanocomposite composition (CNT/Pt) on the chemical oxygen demand (COD) removal and power generation were discussed. The nanocomposite was analyzed using XRD, SEM, and TEM. Moreover, the degree of sulfonation (DS) was measured by NMR. A quadratic model was utilized to forecast the removal of COD and power generation under distinct circumstances. To obtain the maximum COD removal along with maximum power generation, favorable conditions were achieved by statistical and mathematical techniques. The findings proved that MFC could remove 92% of COD and generate 545mW/m2 of power density at optimum conditions of DS=80; and CNT/Pt of 14 wt% CNT- 86 wt% Pt.