Madhu Gopal - Academia.edu (original) (raw)

Papers by Madhu Gopal

International Journal of Environment and Waste Management

Materials Science Forum, 2019

The prepared Polypyrrole/Alumina-Iron oxide nanocomposite has showed 100% adsorption capacity in ... more The prepared Polypyrrole/Alumina-Iron oxide nanocomposite has showed 100% adsorption capacity in removing Copper ions from synthetic waste water. The nanocomposite was analyzed using SEM, TEM, FTIR, XRD and EDX. Batch mode adsorption studies were done to check the feasibility of prepared nanomaterial. Adsorption efficiency of the nanocomposite was measured using UV visible atomic absorption spectrophotometry and found 100 % at pH 8. Influence of inceptive Copper concentration, adsorbent dosage, time of contact, temperature, time with dosage, time and concentration were also tested to determine the optimum value in the uptake of Copper ions. Langmuir and Freundlich adsorption isotherm studies were analysed to understand the process of heavy metals adsorption and found best fitted to Freundlich Isotherm.

The feasibility of treating effluents from a natural rubber latex concentration unit alone and in... more The feasibility of treating effluents from a natural rubber latex concentration unit alone and in admixture with domestic sewage in an oxidation pond was studied. The results clearly indicate that oxidation pond is very effective in treating the effluents from a latex concentration unit in combination with sewage. The BOD reduction ranged from 69 to 93 per cent. The percentage ammoniacal nitrogen removal varied between 4 and 20 while the suspended solids removal efficiency was in the range of 11 to 25 per cent.

Journal of Hazardous Materials, 2010

The hazards associated with major accident hazard (MAH) industries are fire, explosion and toxic ... more The hazards associated with major accident hazard (MAH) industries are fire, explosion and toxic gas releases. Of these, toxic gas release is the worst as it has the potential to cause extensive fatalities. Qualitative and quantitative hazard analyses are essential for the identification and quantification of these hazards related to chemical industries. Fault tree analysis (FTA) is an established technique in hazard identification. This technique has the advantage of being both qualitative and quantitative, if the probabilities and frequencies of the basic events are known. This paper outlines the estimation of the probability of release of chlorine from storage and filling facility of chlor-alkali industry using FTA. An attempt has also been made to arrive at the probability of chlorine release using expert elicitation and proven fuzzy logic technique for Indian conditions. Sensitivity analysis has been done to evaluate the percentage contribution of each basic event that could lead to chlorine release. Two-dimensional fuzzy fault tree analysis (TDFFTA) has been proposed for balancing the hesitation factor involved in expert elicitation.

Georisk: Assessment and Management of Risk for Engineered Systems and Geohazards, 2013

ABSTRACT The study aims to prepare a landslide susceptibility zonation (LSZ) map and quantitative... more ABSTRACT The study aims to prepare a landslide susceptibility zonation (LSZ) map and quantitative validation of the result at a scale of 1:50,000 for the upland catchment of river Meenachil, Kottayam district, Kerala, India by recognizing and mapping the palaeoslide locations and the associated terrain attributes. A bivariate statistical method, known as the weights of evidence modeling, which offers a flexible way of testing the importance of input factors used for landslide susceptibility assessment, were used for the analysis. Fourteen terrain parameters namely, geomorphology, drainage density, soil type, soil thickness, land use, Normalized Difference Vegetation Index (NDVI), slope, aspect, relative relief, slope length, profile curvature, plan curvature, flowpath length and topographic wetness index were generated and its weights were determined. The conditional independence of the evidential themes was assessed by ‘Omnibus test’ and those themes which found to be conditionally independent were integrated to produce the final LSZ map. The results shows that areas having slope less than 16° is classified as stable areas since the active geomorphic processes are absent there, areas covered by side-slope plateau and denudational hills constitutes the very high and high susceptible region and is contributed by the slope between 16° and 45°, facing southwest, west and northwest directions, with extended influence from relative relief, slope length, flowpath length and compound topographic index. The reliability and accuracy of the LSZ map was assessed by the receiver operating characteristic curve analysis and the model shows a prediction accuracy of 89.2% (area under the curve = 0.892). In order to enhance the utility of the results of the present study, a panchayath-wise (the lowest administrative body) susceptibility map was produced and it shows that, among these panchayaths, highly susceptible areas are found in Munnilavu, Talanad, Tikoy and Poonjar Thekkekara. Suggestions are also drawn to optimize the hazard assessment for the region having high landslide susceptibility.

Materials Today: Proceedings, 2021

Abstract The efficacy of different advanced oxidation methods such as UV, UV/ H2O2, Fenton and Ph... more Abstract The efficacy of different advanced oxidation methods such as UV, UV/ H2O2, Fenton and Photo Fenton in removing an emerging contaminant, Mefenamic acid from aqueous solution has been compared in this work. The effect of three major operating parameters such as pH, concentration of oxidant and catalyst on the degradation of the compound was analysed. The removal of the compound occurred slowly in the case of direct photolysis using UVA radiation and only 40% removal could be achieved after one-hour exposure to UV radiation. Fenton process could achieve an improved removal efficiency of 80 percent at 0.02 mM Fe2+ and 8 mM H2O2 concentration in acidic pH range. The removal efficiency improved further in UV/ H2O2 process and 94 percent was noticed in 30 min with 1 mM H2O2 concentration. Photo Fenton process resulted in the maximum removal efficiency of 98% within 20 min in acidic pH range. The fastest and the high removal of Mefenamic acid was obtained in the case of Photo Fenton process, among the four advanced oxidation processes studied.

Pollution Research

In this study the toxic effect of a commonly used anionic synthetic detergent on the growth and b... more In this study the toxic effect of a commonly used anionic synthetic detergent on the growth and biochemical characteristics of Nymphoides indica, a rooted floating macrophyte was evaluated for different concentrations. The effect was studied for a period of one month. The growth characteristics of the plant were assessed in terms of specific leaf area (SLA). Biochemical analysis was done for total chlorophyll content, total protein, membrane lipid peroxidation and electrolyte leakage from tissues. Chlorophyll Stability Index (CSI) and percent Membrane Injury (MI %) were also assessed. The results revealed that the anionic detergent inflicted adverse effects on all the parameters considered. Lipid peroxidation and electrolyte leakage serve as more relevant parameters for detergent induced stress.

IEEE Transactions on Industrial Electronics, 2012

This paper presents the design and analysis of a novel machine family-the enclosed-rotor Halbach-... more This paper presents the design and analysis of a novel machine family-the enclosed-rotor Halbach-array permanentmagnet brushless dc motors for spacecraft applications. The initial design, selection of major parameters, and air-gap magnetic flux density are estimated using the analytical model of the machine. The proportion of the Halbach array in the machine is optimized using finite element analysis to obtain a near-trapezoidal flux pattern. The machine is found to provide uniform air-gap flux density along the radius, thus avoiding circulating currents in stator conductors and thereby reducing torque ripple. Furthermore, the design is validated with experimental results on a fabricated machine and is found to suit the design requirements of critical spacecraft applications.

BACKGROUND Chemical industries pollute the fresh as well as marine water resources. This paper pr... more BACKGROUND Chemical industries pollute the fresh as well as marine water resources. This paper presents the removal of chemical pollutants using filamentous cyanobacteria in column-type photobioreactor. Two different species of cyanobacteria collected from refinery effluent were used for this study. Bio Discs of two different species were prepared separately and compared the removal efficiency. Two different concentrations of effluent were prepared and applied to the photobioreactor. Effluent samples were analysed for phenol, sulphide and COD at every 2 days intervals up to 6 days. Both the microorganisms could grow well in the effluent removing the dissolved chemicals from waste water. Phenol content of Low Strength Effluent (LSE) was reduced to 8 mgL-1 from an initial amount of 103 mgL-1 after 4 days of treatment by Phormidium tenue. Both the organisms could remove sulphide effectively from low strength effluent. Oscillatoria acuminata could not remove higher concentrations of sul...

Environmental Technology, 2016

Aerobic granulation is a promising technology for wastewater treatment. Four operational paramete... more Aerobic granulation is a promising technology for wastewater treatment. Four operational parameters were selected as influencing factors for this study. Aerobic granulation was experimented with three different values of organic loading rate (3, 6 and 9 kg COD m −3 d −1), superficial upflow air velocity (SUAV) (2, 3 and 4 cm s −1), settling time (3, 5 and 10 min) and volume exchange ratio (25%, 50% and 75%) in sequencing batch reactor in nine trials for the optimal performance of aerobic granulation. The influence of compared parameters on five reference parameters (sludge volume index (SVI), time taken for the appearance of granules, size and specific gravity of granules and chemical oxygen demand (COD) removal) was analyzed using grey system theory. The grey relational coefficients and grey entropy relational grade of each parameter were calculated. Hydrodynamic shear force in terms of SUAV was found to have the greatest influence on granule appearance, specific gravity of granules and COD removal efficiency. SVI is greatly affected by settling time. The optimal scopes of all the compared parameters were found.

Reaction Kinetics, Mechanisms and Catalysis, 2021

Selective hydrogenation of acetylene was studied using palladium catalysts supported on different... more Selective hydrogenation of acetylene was studied using palladium catalysts supported on different transition alumina spheres. The alumina supports were prepared by calcining pseudo boehmite alumina sphere at different calcination temperatures; the ρ-Al2O3 used was flash calcined alumina. The alumina supports were characterized using different techniques like XRD, surface area, pore volume and acidity. The Pd/Al2O3 catalyst were prepared, palladium penetration depth was measured using microscopic imaging and the catalyst reducibility were studied by Temperature Programmed Reduction (TPR). The microscopic imaging using TEM were done to study the palladium particle size and nature of particle clusters on the support surface. The catalyst performance evaluation was done in a fixed bed reactor with 1% acetylene in nitrogen feed and studied the impact of support properties on the catalytic activity. The catalyst prepared on γ-Al2O3 support showed the highest conversion and lowest selectivity, whereas the catalyst on α-Al2O3 support has the lower conversion and highest selectivity. Thermogravimetric analysis coupled with mass spectroscopy analysis were done for the spent catalyst to understand the possibilities of heavy component deposition of the catalyst. The catalyst prepared on α-Al2O3 support had the lowest hydrocarbon deposit on the surface whereas the γ and δ alumina showed the highest hydrocarbon deposits on the catalyst surface.

Journal of the Indian Society of Remote Sensing, 2009

A GIS-based statistical methodology for landslide susceptibility zonation is described and its ap... more A GIS-based statistical methodology for landslide susceptibility zonation is described and its application to a study area in the Western Ghats

International Journal of Innovative Research in Science, Engineering and Technology, 2014

Application of chitinous products in waste water treatment has received considerable attention in... more Application of chitinous products in waste water treatment has received considerable attention in recent years. The Chitosan, deacetylated chitin derivative is the most interesting biopolymer in the world of adsorption science.The preparation of chitosan beads and chitosan membranes were explained in this paper. The properties of chitosan flake, beads, and film was studied with different analytical method such as CHN, SEM, FTIR, DSC, etc. Chemical modification of chitosan membranes and beads were performed by crosslinking with glutaraldehyde and its properties were analysed.The Adsorption studies of Hg(II) ion was carried out in a batch process at room temperature in static manner with varying parameters such as pH of solution, adsorbent concentration and different Chitosan forms. Metal concentration was measured using ICP AES. It has been shown that cross linked chitosan beads have higher adsorption degree compared to chitosan flakes and cross linked chitosan membrane. The removal ...

Pesticides belong to the class of persistent chemicals in the environment which cause serious hea... more Pesticides belong to the class of persistent chemicals in the environment which cause serious health hazards. Advanced Oxidation Processes (AOPs) represent the fast developing area in water and wastewater treatment by which non biodegradable and difficult to biodegradable compounds can be removed. This paper discusses the use of ozonation for the removal of insecticide acetamiprid from water. Response surface Methodology was used for the optimisation of the process parameters: ozone flow rate and pH.

Various novel cooling solutions have been proposed to circumvent peak heat dissipation as part of... more Various novel cooling solutions have been proposed to circumvent peak heat dissipation as part of endeavours in developing effective self-contained cooling methods for high heat flux management in electronics cooling systems. Dynamic thermal modelling and simulation of a heat sink making use of subcooled flow boiling in microchannel in presence of a phase changing material encapsulated inside fin array is presented here. Dynamic heat transfer model takes care of the heat stored in phase changing material, heat transferred by natural convection in addition to the subcooled boiling in micro channel. Simulations have been performed based on the developed heat transfer model, for wide range of time varying heat input from the processor as well as mass flux admitted through the channel and the condition of subcooled boiling in micro channel have been assessed in detail. Analysis of the response shows that the heat absorbed in variable area PCM storage helps to damp the wall superheat wit...