Sivanesan Subramanian

Synthesis of biodiesel from Neem oil using sulfated zirconia via tranesterification

Sulfated zirconia (SZ) is a widely used catalyst, which is synthesized by a solvent free method and the synthesized catalyst has been characterized. Neem Methyl Ester (Biodiesel) was prepared by a two-step process of esterification and transesterification from Neem oil with methanol in the presence of catalyst. Acid catalyst was used for the esterification and alkali catalyst (KOH) for the transesterification reaction. Optimal Free Fatty Acid (FFA) conversion was achieved using 1 wt% SZ as an acid catalyst with a methanol-to-oil molar ratio of 9:1, temperature of 65oC and reaction time of 2 h. The acid value was reduced to 94% of the raw oil (24.76 mg KOH/g), which confirmed the conversion. Consequently, this pretreatment reduces the overall complexity of the process and a conversion efficiency of 95% is achieved when pretreated oil reacts with methanol in the presence of KOH.

Two-step biodiesel production from Calophyllum inophyllum oil: Optimization of modified β-zeolite catalyzed pre-treatment

In this study, a two-step process was developed to produce biodiesel from Calophyllum inophyllum oil. Pre-treatment with phosphoric acid modified β-zeolite in acid catalyzed esterification process preceded by transesterification which was done using conventional alkali catalyst potassium hydroxide (KOH). The objective of this study is to investigate the relationship between the reaction temperatures, reaction time and methanol to oil molar ratio in the pre-treatment step. Central Composite Design (CCD) and Response Surface Methodology (RSM) were utilized to determine the best operating condition for the pre-treatment step. Biodiesel produced by this process was tested for its fuel properties.

Removal of free fatty acid in Azadirachta indica (Neem) seed oil using phosphoric acid modified mordenite for biodiesel production

In this study free fatty acids present in Azadirachta indica (Neem) oil were esterified with our synthesized phosphoric acid modified catalyst. During the esterification, the acid value was reduced from 24.4 to 1.8 mg KOH/g oil. Synthesized catalyst was characterized by NH(3) TPD, XRD, SEM, FTIR and TGA analysis. During phosphoric acid modification hydrophobic character and weak acid sites of the mordenite were increased, which lead to better esterification when compared to H-mordenite. A kinetic study demonstrates that the esterification reaction followed pseudo-first order kinetics. Thermodynamic studies were also done based on the Arrhenius model.

Carrier-free co-immobilization of xylanase, cellulase and β-1,3-glucanase as combined cross-linked enzyme aggregates (combi-CLEAs) for one-pot saccharification of sugarcane bagasse

Combined cross-linked enzyme aggregates (combi-CLEAs) are an innovative prospect and a lucrative technology. The present study addresses the preparation, characterization and application of combi-CLEAs with xylanase, cellulase and β-1,3-glucanase to achieve one-pot bioconversion of lignocellulosic biomass to fermentable sugars. A three-phase partitioning (TPP) method was used to aggregate the enzymes. Glutaraldehyde (100 mM) was employed as a cross-linker with the cross-linking time of 7.5 h. Scanning electron microscopy of the tri-enzyme biocatalyst has a coarse-grained appearance. Combi-CLEAs were more thermally stable, retaining about 70% of their initial activity at 70 °C compared to 30% for the free enzyme. The storage stability of combi-CLEAs was more than 97% of their activity after incubation for 11 weeks at 4 °C, whereas the free enzymes retained about 65% of initial activity. The residual activity of combi-CLEAs remained constant at 90% until the sixth cycle. Contrary to free enzymes that remain in the hydrolysate, which prevents their recovery, reuse of combi-CLEAs was possible. Free enzymes hydrolyze the ammonia cooked sugarcane bagasse at about 73%, whereas the combi-CLEAs resulted in maximum hydrolysis of about 83.5% in 48 h.

A study on the removal of heavy metals and anionic dyes from aqueous solution by amorphous polyamide resin containing chlorobenzalimine and thioamide as chelating groups

Poly(chlorobenzalimino thiourea amide) (PCBA) resin was synthesized by using the phosphorilation poly condensation method. PCBA was characterized by analytical techniques, and it was used for the adsorption of heavy metals (Ni2+ and Zn2+) and anionic dyes (methyl orange (MO) and acid orange (AO)). The variables which affect the adsorption efficiency, such as pH, adsorbate concentration, adsorbent dose and contact time were studied. The results show that the adsorption of Ni2+, Zn2+, MO and AO follows the pseudo-second order kinetic model. The maximum monolayer adsorption capacity of PCBA for Ni2+, Zn2+, MO and AO, calculated using Langmuir isotherm is 191.2, 247.1, 153.8, 149 mg/g, respectively. Surface area (21.1m2/g) and crystal size are 21.1m2/g and 0.35 nm, respectively. High efficiency of the polymeric resins may be due to their amorphous nature and the presence of strong binding sites in the polymer structure. Thermodynamic parameters such as change in standard free energy change, enthalpy and entropy ΔG0, ΔH0 and ΔS0 were evaluated, and the adsorption process was found to be feasible, exothermic and spontaneous. Desorption studies show that adsorption efficiency of PCBA was retained even after four cycles.

Biodegradation of Remazol Brilliant Blue R using isolated bacterial culture (Staphylococcus sp. K2204)

ABSTRACT Staphylococcus sp. K2204, a bacterial isolate, was employed in this work to decolorize Remazol Brilliant Blue R (RBBR), which belongs to the anthraquinone class of textile dye. Staphylococcus sp. K2204 biodegraded 100 mg/L RBBR at 37°C under static condition with the help of extracellular laccase and peroxidases. The products of RBBR degradation were characterized using analytical tools including mass spectral technique. The phytotoxicity tests evaluated the toxicity of RBBR and the products of biodegradation. The research outlined here is the first attempt to utilize Staphylococcus sp. K2204 for remediating the wastewater containing anthraquinone textile dye.

Bioconversion of Lignocellulosic Biomass to Fermentable Sugars by Immobilized Magnetic Cellulolytic Enzyme Cocktails

Enzyme cocktails of reusable, highly stable cellulolytic enzymes play an inevitable role in bioconversion of biomass to biofuels economically. Cellulase, xylanase and β-1,3-glucanase bound silica-amine functionalized iron oxide magnetic nanoparticles (ISN-CLEAs) were prepared and used as the biocatalyst for the depolymerization of cellulosic biomass into monomeric sugar in the present study. The Fe3O4-NPs and Fe3O4@SiO2-NH2-NPs and ISN-CLEAs had an average hydrodynamic size of 82.2, 86.4, and 976.9 nm, respectively, which was confirmed by dynamic light scattering (DLS). About 97% of protein binding was achieved with 135 mM glutaraldehyde at 10 h of cross-linking time and successful binding was confirmed by Fourier transform infrared spectroscopy (FTIR). The ISN-CLEAs exhibited the highest thermal stability of 95% at 50 °C for 2 h and retained extended storage stability of 97% compared to 60% of its free counterpart. Besides, cross-linking allowed ISN-CLEAs reuse for at least eight consecutive cycles retaining over 70% of its initial activity. ISN-CLEAs exhibited approximately 15% increase in carbohydrate digestibility on sugar cane bagasse and eucalyptus pulp than the free enzyme.

Review on nanoadsorbents: a solution for heavy metal removal from wastewater

Elimination of heavy metals from contaminated streams is of prime concern due to their ability to cause toxic chaos with the metabolism of flora and fauna alike. Use of advanced nano-engineered technologies such as the innovative combination of surface chemistry, chemical engineering fundamentals and nanotechnology opens up particularly attractive horizons towards treatment of heavy metal contaminated water resources. The obtained product of surface engineered nanoadsorbent produced has successfully proven to show rapid adsorption rate and superior sorption efficiency towards the removal of a wide range of defiant heavy metal contaminants in wastewater. The use of these materials in water treatment results in markedly improved performance features like large surface area, good volumetric potential, extra shelf-lifetime, less mechanical stress, stability under operational conditions with excellent sorption behaviour, no secondary pollution, strong chelating capabilities and they are easy to recover and reuse. This review intends to serve as a one-stop-reference by bringing together all the recent research works on nanoparticles synthesis and its advantages as adsorbents in the treatment of heavy metal polluted wastewater that have so far been undertaken, thereby providing researchers with a deep insight and bridging the gap between past, present and future of the elegant nanosorbents.

Production of thermostable multiple enzymes from Bacillus amyloliquefaciens KUB29

Abstract A strain of Bacillus amyloliquefaciens KUB29 was identified by 16S ribosomal RNA sequencing (Genbank: MF772779.1). Production of thermostable protease, amylase and lipase were done by the isolated strain. The produced enzymes were partially purified by ammonium precipitation followed by dialysis process. Protease and lipase enzymes are effectively used in bio-oil extraction from proteinaceous sample followed by transesterification to produce methyl ester. Amylase enzyme is widely used in food and laundry industry. The produced enzymes are active at thermophilic condition of 55 °C. Use of these enzymes in biofuel production process will make the process cleaner and greener.

Auxin biosynthetic intermediate genes and their role in developmental growth and plasticity in higher plants

Auxins are a group of phytohormones that regulate several aspects of plant growth and development. Indole-3-acetic acid (IAA) is the predominant form of auxin in plants and several IAA biosynthetic pathways have been previously proposed but remain genetically uncharacterized. One of the proposed pathways is the indole-3-pyruvic acid (IPyA) pathway, which is inferred to regulate key developmental processes such as apical hook formation and shade avoidance. Recent molecular evidence suggests the existence of the pathway in higher plants but remains unverified due to the elusive nature of IPyA in vitro. Extending on these recent advances, this research was aimed at investigating aspects of IPyA-dependent auxin biology in Pisum sativum (pea) using reverse genetics, expression profiling, and analytical techniques. As a result the genes PsTAR2, PsTAR 5g Mt 80, and PsTAR 5g Mt 90, which are inferred to encode key enzymes in the IPyA pathway, were cloned. On expression analysis PsTAR2 was found to be slightly heightened in response to IPyA-inducing conditions (shade) while IAA levels remained unaltered contrary to previous reports. Moreover, the inferred homologs PsTAR 5g Mt 80 and PsTAR 5g Mt 90 appeared down-regulated in the same conditions suggesting functional divergence in the gene family. Thus, PsTAR2 was thought to be solely responsible for regulating IPyA-dependent auxin synthesis. Consequently, using a reverse genetic approach, called TILLING, the PsTAR2 gene was mutated in order to study the down-stream effects of IPyA deficiency. The procedure is currently underway and in the process of isolating two novel pstar2 (IPyA) mutant lines consisting of a missense mutation (pstar24280) and a highly desired knockout mutation (pstar2918). On completion the novel mutants are anticipated to be indispensable to future IPyA-auxin investigations in higher plants. In light of the unstable nature of IPyA, a protocol has been formulated using UPLC for fractioning followed by MS/MS analysis. This technique appears to be very promising as a robust IPyA detection protocol in plant extracts.