Laxmi Gayatri Sorokhaibam

Industrial wastewater treatment for fertilizer industry—A case study

Wastewaters from chemical fertilizer industry mainly contain organics, alcohols, ammonia, nitrates, phosphorous, heavy metals such as cadmium and suspended solids. The nature of effluent streams va...

A Non-catalytic Deep Desulphurization Process using Hydrodynamic Cavitation

A novel approach is developed for desulphurization of fuels or organics without use of catalyst. In this process, organic and aqueous phases are mixed in a predefined manner under ambient conditions and passed through a cavitating device. Vapor cavities formed in the cavitating device are then collapsed which generate (in-situ) oxidizing species which react with the sulphur moiety resulting in the removal of sulphur from the organic phase. In this work, vortex diode was used as a cavitating device. Three organic solvents (n-octane, toluene and n-octanol) containing known amount of a model sulphur compound (thiophene) up to initial concentrations of 500 ppm were used to verify the proposed method. A very high removal of sulphur content to the extent of 100% was demonstrated. The nature of organic phase and the ratio of aqueous to organic phase were found to be the most important process parameters. The results were also verified and substantiated using commercial diesel as a solvent. The developed process has great potential for deep of various organics, in general, and for transportation fuels, in particular.

Differentiating Process Performance of Various Coagulants in Removal of Congo red and Orange G Dyes

Abstract Two refractory azo dyes- Congo red and Orange G, especially at high concentrations were subjected to coagulation with different conventional coagulants and newer formulations developed from Aluminum sulfate, Iron (III) chloride, Aluminium chloride, Poly diallydimethylammonium chloride (Poly DADMAC) and Poly Aluminium Chloride (PAC). The highest COD reduction of 99 % was obtained with PAC SAB 18 (Powder Grade PAC) for Congo red at pH 4.5 while the color removal of 99 % was achieved with almost all the coagulants in the present study at specific pH within 3–8. The optimum dose for the iron-based coagulant is 200 mg/L while that of aluminum-based coagulants and PAC is 150–200 mg/L. Results showed that Orange G was more difficult to remove with a maximum COD removal of 65 % and 35 % color removal using various formulations. The combinational formulations of inorganic-inorganic and inorganic-organic produced a substantial enhancement in COD and color removal and reduced sludge. PAC-Fe30/70 produces the minimum sludge of 50 mL/g on Congo red. pH in the range 3–9 showed high reductions in COD and color (90–99 %) for Congo red while jerky rise in COD and color reduction was observed in the case of Orange G after pH 9. An attempt to understand the dye coagulation mechanism has been made based on the specific difference in dye structure and cation speciation.

Exploiting functionalities of biomass in nanocomposite development: application in dye removal and disinfection along with process intensification

A green synthesis of multifunctional superparamagnetic nanocomposites using the whole unripened fruit of Cassia fistula (Golden shower) with potential for removal of both cationic and anionic dyes and antimicrobial property is reported for the first time in the present work. A natural medium in the form of clarified butter was used to enhance the multifunctional character. The surface morphology, textural characteristics and composition of the prepared nanoparticles and composites were studied to understand the multifunctional nature. The dye removal was investigated for four different dyes, namely methyl blue, Congo red, rhodamine-B and auramine. Iron nanoparticles were largely effective in the removal of acidic dyes, while the magnetic nanocomposites were effective for the removal of both acidic and basic dyes which can be attributed to the functionalities imparted from Cassia fistula and clarified butter. The dye removal behavior can be significantly enhanced (~ 50%) using process intensification–adsorption coupled with acoustic cavitation, which also indicated a reduced adsorbent loading as compared to the conventional adsorptive dye removal. The nanomaterials were completely separated from dye solution with absolute ease of separation by applying simple magnetic field. Also, the developed materials were useful in disinfection of E. coli with a high efficiency of 90% confirming significant antimicrobial property at lower concentrations.Graphical Abstract

Ion Exchange Resin Catalyzed Reactions-An Overview

This chapter gives an overview of ion exchange resins as catalyst for a variety of reactions. Emphasis is placed on the use of resin as a catalyst rather than on reactions. Various aspects of resin catalysis, such as types of reactions where resin can be used, the physical form of resin and activity, and issues pertaining to its application as a catalyst are discussed. Advantages and disadvantages of resins as catalyst for different types of reactions are highlighted. Aspects like reactor configurations, selection of resin, process integration, process separations and the environmental impact of using resins as catalysts are also included. Possible future developments in the ion exchange catalysis area are also highlighted.

Phenolic Wastewater Treatment: Development and Applications of New Adsorbent Materials

The present chapter describes the development of some newer adsorbent materials, especially derived from biomass for treating phenolic wastewater. Synthesis methods are briefly discussed, and modifications in the form of adsorbents are elaborated with the help of characterization of the materials. These materials were tested for removal of phenolic compounds from wastewaters. The presented approach for developing new adsorbent materials will be useful for realizing cost-effective treatment of phenolic and other wastewater.The present chapter describes the development of some newer adsorbent materials, especially derived from biomass for treating phenolic wastewater. Synthesis methods are briefly discussed, and modifications in the form of adsorbents are elaborated with the help of characterization of the materials. These materials were tested for removal of phenolic compounds from wastewaters. The presented approach for developing new adsorbent materials will be useful for realizing cost-effective treatment of phenolic and other wastewater.