Anionic gemini surfactants are a new class of surfactants that comprise of two anionic head groups and two hydrophobic tails separated by a spacer group. Anionic gemini surfactants have low cmc values and show extraordinary surface activity. These surfactants have good water solubility and their ability to form micelles and lowering surface tension characteristics are fairly good as compared to conventional anionic surfactants. These surfactants have excellent lime soap dispersing ability (LSDA) too. Because of their higher surface activity these surfactants are used as promising surfactants in industrial detergency and emulsification. These surfactants are cost effective in area such as laundry detergent compositions, soil clean up, enhanced oil recovery and hydrotropic agents. This review deals with structure, synthesis, critical micelle concentration, surface active properties, performance properties, uses and biodegradability of anionic geminis.
Four vegetable seed oils viz.,Bitter gourd (Momordica charentia), Small bitter gourd (Momordica dioica), Bottle gourd (Lagenaria siseraria), Ridge gourd (Luffa acutangula) seed, solvent extracted oils were evaluated against mustard aphid, Lipaphis erysimi Kalt., in the farm of mustard crop. All the natural insecticides (Vegetable oils) were found very effective and caused 100% mortality (indicated by non-motility of the insects) at 6% conc. in 24 hrs. Seed oil of Small bitter gourd and Bottle gourd were found to be satisfactory natural insecticide giving 100% mortality at 4% conc. in 24 hrs. Lower concentrations up to 2% was also found effective but require longer time (up to 32 hrs.) to give 100% mortality in case of Small bitter gourd and Bottle gourd. No further spray was given to crop and also no further infestation of aphid found in the vegetable oil treated crop.
The present work has synthesized two polyethylene glycol (PEG) esters with two di-basic acids by bioesterification process and has investigated the interface properties like interfacial tension, surface excess concentration, minimum surface area per mole and as well as the Gibbs adsorption and thermodynamic behavior of micelle formation for the PEG-400 esters of the two acids. The esterification reaction was carried out by agitating the reactants in different molar ratios with Mucor miehei (RMIM) lipase enzyme at 70-75°C for 7 hours and 2 mm of Hg pressure. The conversion of PEG to esters ranged from 40-64% depending on the molecular size of di-basic acids.
Lipase-catalyzed acetylation of 1-alkanol with vinyl acetate to give alkyl acetate has been studied kinetically using Burkholderia cepacia lipase, six alcohols and different organic solvents. The rate constants kA and kB with respect to vinyl acetate and 1-alkanol determined from the double reciprocal plots, v-1vs. [vinyl acetate]-1 and v-1vs. [1-alkanol]-1 respectively, where v is the initial rate of the reaction. The rate ratio kB/kA was larger than unity except some cases: the rate in acetylation of active serine residue in the lipase with vinyl acetate was slower than that of 1-alkanol with the acetyl-enzyme intermediate. The rate constant kA was independent of the solvent hydrophobicity log P (where P is a partition coefficient of a given solvent between octanol and water), however, kB increased with log P. Both rate constants were different depending on the structure (carbon number CN) of 1-alkanol.
Nanostructured ZnO particles present in skin-care cosmetics and UVB/UVA sunscreen products generate strong oxidizing species (free radicals) when illuminated with UV radiation that can damages human skin and the horny layer. Damage to DNA by ZnO and other pigmentary ingredients in sunscreen formulations under artificial and solar UV exposure has been examined by Agarose gel electrophoresis using pUC 18 DNA plasmids (2686 base-pairs). Initial photoinduced oxidative damage done to DNA plasmids have been probed by nicking assays under in vitro conditions for ZnO. The effects of nanosize ZnO and CeO2 particles, and the newly developed CaO-doped and SiO2-coated CeO2 pigment are compared when subjected to artificial (75-W Hg-lamp) and solar UV radiation. Supercoiled DNA plasmids undergo one nick to produce the relaxed form, followed by a second nick yielding the linear form of the plasmids. The DNA constituents deoxyadenosine-5’-monophosphate (dAMP), guanosine-5’-monophosphate (GMP) and cytidine-5’-monophosphate (CMP) have been examined to assess the photooxidative damage done to these nucleotides under photocatalytic conditions using the cosmetic/sunscreen ZnO pigment. Adsorption of the nucleotide through the phosphate on the positively charged ZnO surface, followed by attack of the ribose/phosphate backbone by photogenerated · OH (and/or · OOH) radicals on the ZnO surface lead to the degradation of the dAMP’s ribose moiety and subsequently to decomposition of the adenine base residue. About 90% mineralization of the ribose/phosphate backbone occurred as evidenced by formation of H2PO4- ions after only 30 min of UV irradiation. The nitrogen atoms of the adenine base were converted to NO3- and NH4+ ions. About 45% of the organic carbons constituting the dAMP ribose backbone was mineralized to CO2 within 8 h of UV irradiation occurring through formation of carboxylic acid intermediates (succinic, acetic and formic), with 85% of the remaining nucleobase ultimately mineralized after 48 h of UV irradiation. Similar occurrences were seen for the GMP and CMP nucleotides.
Nanoparticles of Titanium dioxide (TiO2) was successfully synthesized from simple aqueous peroxo route using TiOSO4 and H2O2 as the precursors. Amorphous titanium-peroxo complex powder was obtained at room temperature, which was then converted into anatase by heat-treating at 300°C. This new method is simple, inexpensive, environmentally benign and promising to be used for the preparation of large quantity of TiO2 nanoparticles.