Faculty Publications

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    Particle Removal by Surfactants During Semiconductor Cleaning
    (Elsevier, 2022) Yerriboina, N.P.; Park, J.-G.; Poddar, M.K.
    Particle removal during semiconductor processing is very crucial to meet the requirements of device reliability and yield. Several process steps are involved during semiconductor manufacturing, and cleaning steps are necessary before and after each processing step to make the wafer surface ready for the next process. As wafers may have different kinds of surfaces and particulate contaminants, the cleaning should be carefully optimized to provide the necessary physical forces and/or chemical forces. In this chapter, two major semiconductor processing steps are discussed for the application of surfactants in removing particles: wafer cleaning and PCMP (post-chemical mechanical planarization) cleaning. There are several issues or challenges to remove the particles from these processing steps. Surfactants play a critical role in preventing the redeposition of the particles during the cleaning process by modifying surfaces to have repulsive interaction forces between particles and wafer surfaces. Some typical surfactants used for the semiconductor cleaning process and their characteristics are discussed. Various mechanisms involved in particle removal by surfactants are explained. They also play an important role in Si wafer cleaning in controlling the etch rates by adsorbing on the wafer surface. A PCMP cleaning is necessary to remove the slurry particles attached to the different substrates (such as dielectrics, metals, III-V materials) after the CMP process. These particles are removed by adding suitable surfactants to the cleaning solutions. The role of surfactants in particle removal depends on the type of substrate. A variety of surfactants used for the PCMP cleaning process are also discussed. © 2022 Elsevier Inc. All rights reserved.
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    Biopolymeric Nanofibrous Materials for Environmental Remediation
    (wiley, 2022) Pallavi, K.C.; Isloor, A.M.
    The present content gathers information regarding the use of nanofibrous materials fabricated out of biopolymers in environmental problems. Biopolymers are environment-friendly and nonhazardous in character. Various conventional methods have been employed so far to solve problems, such as water pollution, air contamination, and soil infertility. Membranes of different types, filtration systems, and various sorbents have been found useful in the removal of contaminants. Apart from all those, nanofibrous materials attain great importance due to their noncomparable high surface area, minute pore size, diameter in the nanorange, and good adsorptive property. Nanofibers can be fabricated out of diverse polymers through various techniques, such as electrospinning. The surface modifications, such as chemical grafting and oxygen plasma treatment induced functional group insertion, can be done, which imparts high potential in respective applications. The present review chapter describes about nanofiber fabrication technique, properties of the resultant nanofiber mat, and their importance in environmental remediation, such as removal of airborne and waterborne contaminants. © 2022 Scrivener Publishing LLC.
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    Effect of 1,2,3benzotriazole on the corrosion of aged 18Ni250 grade Maraging steel in Phosphoric acid solution
    (Institute of Physics Publishing helen.craven@iop.org, 2018) Naik, P.; Nayak, J.; Girish, L.V.; Somashekhar, T.M.; Bhanuprakash, S.H.; Rahul, S.
    The 18 Ni 250 grade maraging steel is a potential high strength steel for advanced technologies such as aerospace, nuclear, and sporting goods. Phosphoric acid and Nitric acid solutions are used in pickling of delicate and precision items where re-rusting after pickling has to be avoided. The present work addresses the study of corrosion behaviour and inhibition using 1,2,3 benzotriazole of aged 18 Ni 250 grade maraging steel in phosphoric acid medium at higher concentration by Potentiodynamic Polarization Technique. The corrosion rates were determined in 1M, 1.5M and 2M by Tafel extrapolation technique in the temperature range 300C-500C with different concentrations of inhibitor. The results indicate that the corrosion rate increases with increase in acid concentration and temperature.Inhibition efficiency of 1,2,3benzotriazolewas found to increase with the increase in 1,2,3 benzotriazole concentration and decrease with the increase in temperature.The activation energy Ea and other thermodynamic parameters (ΔG,ΔH# andΔS#) have been evaluated and discussed. The standard free energy of adsorptionΔGads values indicates that the adsorption is of mixed type. Scanning electron microscopy (SEM) study confirmed the formation of an adsorbed protective film on the metal surface. © Published under licence by IOP Publishing Ltd.
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    Effect of media characteristics on performance of upflow aerobic biofilters
    (2008) Srinikethan, G.; Shrihari, S.; Pradeepan, V.S.
    Laboratory studies were conducted to assess the influence of media related factors such as porosity, pore size, particle size and specific surface area on the performance of upflow aerobic biofilters (ABFs). Three simple models of 8 litre capacity upflow submerged ABFs packed with support media of size 40 mm, 20 mm and 10 mm respectively were installed. The hydraulic retention time (HRT) was maintained as 12 hours. The study was carried out for a period of 90 days. The reactor performance indicated that the aerobic biofilter (ABF-3), associated with media of lowest porosity, pore size, particle size and highest specific surface area, demonstrating the highest BOD and COD removal efficiency of 93.32 % and 85.01 % respectively.
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    Studies on the removal of Pb(II) from wastewater by activated carbon developed from Tamarind wood activated with sulphuric acid
    (2008) Singh, C.K.; Sahu, J.N.; Mahalik, K.K.; Mohanty, C.R.; Mohan, B.R.; Meikap, B.C.
    The low-cost activated carbon were prepared from Tamarind wood material by chemical activation with sulphuric acid for the adsorption of Pb(II) from dilute aqueous solution. The activated carbon developed shows substantial capacity to adsorb Pb(II) from dilute aqueous solutions. The parameters studied include physical and chemical properties of adsorbent, pH, adsorbent dose, contact time and initial concentrations. The kinetic data were best fitted to the Lagergren pseudo-first-order and pseudo-second order models. The isotherm equilibrium data were well fitted by the Langmuir and Freundlich models. The maximum removal of lead(II) was obtained 97.95% (experimental) and 134.22 mg/g (from Langmuir isotherm model) at initial concentration 40 mg/l, adsorbent dose 3 g/l and pH 6.5. This high uptake showed Tamarind wood activated carbon as among the best adsorbents for Pb(II). © 2007 Elsevier B.V. All rights reserved.
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    Biological sulfide oxidation using autotrophic Thiobacillus sp.: Evaluation of different immobilization methods and bioreactors
    (2009) Ravichandra, P.; Gopal, M.; Jetty, A.
    Aims: Evaluation of various immobilization methods and bioreactors for sulfide oxidation using Thiobacillus sp. was studied. Methods and Results: Ca-alginate, K-carrageenan and agar gel matrices (entrapment) and polyurethane foam and granular activated carbon (adsorption) efficacy was tested for the sulfide oxidation and biomass leakage using immobilized Thiobacillus sp. Maximum sulfide oxidation of 96% was achieved with alginate matrix followed by K-carrageenan (88%). Different parameters viz. alginate concentration (1%, 2%, 3%, 4% and 5%), CaCl2 concentration (1%, 2%, 3%, 4% and 5%), bead diameter (1, 2, 3, 4 and 5 mm), and curing time (1, 3, 6, 12 and 18 h) were studied for optimal immobilization conditions. Repeated batch experiments were carried out to test reusability of Ca-alginate immobilized beads for sulfide oxidation in stirred tank reactor and fluidized bed reactor (FBR) at different sulfide concentrations. Conclusions: The results proved to be promising for sulfide oxidation using Ca-alginate gel matrix immobilized Thiobacillus sp. for better sulfide oxidation with less biomass leakage. Significance and Impact of the Study: Biological sulfide oxidation is gaining more importance because of its simple operation. Present investigations will help in successful design and operation of pilot and industrial level FBR for sulfide oxidation. © 2009 The Society for Applied Microbiology.
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    Adsorption of phenol on granular activated carbon from nutrient medium: Equilibrium and kinetic Study
    (2009) Dabhade, M.A.; Saidutta, M.B.; Murthy, D.V.R.
    This paper presents the adsorption of phenol on granular activated carbon (GAC) from nutrient medium suitable for microorganisms' growth and also the subsequent biodegradation. Two parameter Langmuir and Freundlich adsorption isotherm models were studied using large range of phenol concentration (50-1000 mg/L). In low range of phenol concentration (50-300 mg/L), correlation coefficient, normalized deviation "g% and separation factor were 0.9989,2.18% and 0.38-0.78 respectively, while for higher concentration range (400-1000 mg/L), the corresponding values were 0.9719, 1.9% and 0.45- 0.67. Freundlich isotherm gave correlation coefficient of 0.9984, 1/n. value of 0.7269 and normalized deviation of 4.55%. Comparison based on R2, adjusted R2, normalized deviation and root mean square deviation (RMSD) showed that the Redke-Prausnitz isotherm model gives better prediction compared to other models. Adsorption of phenol follows pseudo second order kinetics with correlation coefficient closer to one. Biodegradation study using immobilized cells of Nocardia hydrocarbonoxydans on GAC showed that, biodegradation begins well before GAC reaches the saturation period.
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    Improved utilization of desiccant material in packed bed dehumidifier using composite particles
    (2011) Ramzy K, A.; Kadoli, R.; Ashok Babu, T.P.
    Solid desiccant dehumidifiers are widely used in drying processes. In most of these dehumidifiers, the desiccant material is used as packed bed of granule or spherical particles. Investigations of intra-particle heat and mass transfer processes has shown that the entire portion of the particle is not participating effectively during adsorption as well as desorption processes [Pesaran AA, Mills F. Moisture transport in silica gel packed beds-I. Theoretical study. International Journal of Heat and Mass Transfer 1987; 30: 1037-49]. This is because the diffusion rate is very small compared to that of convection. In the present work, a new desiccant composite particle, in which the unutilized portion of the spherical desiccant particle is replaced with an inert particle, is proposed. By replacing the conventional particles with composite particles for the same mass of desiccant material, the available area for heat and mass transfer increases and more amount of desiccant material is effectively utilized. Further, in order to ascertain the improvement in the performance of the desiccant bed using the composite particles, various factors like thermo-physical properties of the inert material, composite particle thickness ratio, bed configuration, bed volume, the pressure drop and the increase in total adsorbed or desorbed mass have to be considered. In view of this, a theoretical investigation of the operation of vertical solid desiccant packed bed dehumidifier, using both conventional silica gel particles as well as the new proposed composite silica gel particles has been reported. A modified solid side resistance (MSSR) model is developed for the prediction of intra-particle temperature and water content profiles. Results of the present theoretical models, when applied to packed bed of conventional silica gel particles, agree well with the experimental results from the literature for both desorption and adsorption processes. From the theoretical results, more utilization for the desiccant material is obtained when ordinary silica gel particles are replaced by composite silica gel particles. For the same amount of desiccant material and same mass flow rate of air, using particles of 0.2 thickness ratio the pressure drop decreases by about 60% for the case investigated. In addition, an increase of about 11.07% and 20.46% in total mass adsorbed and desorbed respectively are obtained. At the time when adsorption process ends, an increase of 15.5% in the bed effectiveness has been obtained. In addition, the expected improvement in total mass adsorbed and desorbed is observed to be dependent on the inert material thermo-physical properties for thickness ratio less than 0.5. An optimization technique relating the composite particle design, resulting savings in pressure drop and bed volume increase is proposed. © 2010 Elsevier Ltd.
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    Removal of remazol brilliant blue dye from dye-contaminated water by adsorption using red mud: Equilibrium, kinetic, and thermodynamic studies
    (2012) Ratnamala, G.M.; Shetty K, K.V.; Srinikethan, G.
    Utilization of industrial solid wastes for the treatment of wastewater from another industry could help environmental pollution abatement, in solving both solid waste disposal as well as liquid waste problems. Red mud (RM) is a waste product in the production of alumina and it poses serious pollution hazard. The present paper focuses on the possibility of utilization of RM as an adsorbent for removal of Remazol Brilliant Blue dye (RBB), a reactive dye from dye-contaminated water. Adsorption of RBB, from dye-contaminated water was studied by adsorption on powdered sulfuric acid-treated RM. The effect of initial dye concentration, contact time, initial pH, and adsorbent dosage were studied. Langmuir isotherm model has been found to represent the equilibrium data for RBB-RM adsorption system better than Freundlich model. The adsorption capacity of RM was found to be 27.8 mg dye/g of adsorbent at 40 °C. Thermodynamic analysis showed that adsorption of RBB on acid-treated RM is an endothermic reaction with ?H0 of 28.38 kJ/mol. The adsorption kinetics is represented by second-order kinetic model and the kinetic constant was estimated to be 0.0105 ± 0.005 g/mgmin. Validity of intra-particle diffusion kinetic model suggested that among the mass transfer processes during the dye adsorption process, pore diffusion is the controlling step and not the film diffusion. The process can serve dual purposes of utilization of an industrial solid waste and the treatment of liquid waste. © Springer Science+Business Media Dordrecht 2012.