Chitosan pretreatment

In general, activities of chitosan based catalysts prepared by impregnation method in hydrogenation of unsaturated organic compounds were comparable with those of traditional heterogeneous catalyst (as calculated per 1 mole of metal). It should be noted that the chitosan pretreatment influenced very much the catalyst activity. For instance, immediate Pd deposition from alcohol solution on dry chitosan fibers or micro beads led to almost completely inactive catalytic systems, regardless of the metal content. On the other hand, metal deposition on chitosan micro beads or fibers preliminary swollen in water dramatically improved the catalytic activity. 

Table 19.3 Effect of chitosan pretreatment on fastness of C. I. Direct Red 81 dyed fabric...

Potato is a tuberous crop from the perennial Solanum tuberosum of the Solanaceae family. It is an essential crop in Europe and Asia. China is now the world s largest potato-producing country. The effect of the chitosan-induced resistance to viral infection was investigated in potato plants. The plants were sprayed with different molecular weights of chitosan solution (1 mg/mL) and the greatest antiviral activity was shown by 120 kDa chitosan. In another experiment, potatoes were infected with potato virus X after chitosan pretreatment. It was found that chitosan treatment significantly decreased the number of systemically infected plants compared to control, and the treated leaves also accnmnlated less amount of virus than the control leaves (Chirkov et al. 2001). 

Du et al. reported a sensitive, fast and stable amperometric sensor for quantitative determination of OP insecticide, triazophos [14], Where, AChE was immobilized on MWNTs-chitosan (MC) composite matrix. Prior to enzyme immobilization, GCE surface was activated by applying a potential of +1.75 V for 300 s and scanned in the potential range +0.3 to +1.25V and +0.3 to -1.3V until a steady-state curve was obtained. This pretreated GCE surface was coated with 2.0 pi of MWCNTs, chitosan and glutaraldehyde mixture, followed by coating 4 pi of AChE solution, dried and used. CV results show that the oxidation peak of thiocholine occurs at +0.66V with much higher peak height at AChE/MC/GCE than at AChE/CS/GCE without MWCNTs. This shows that MWCNTs presence lowers the oxidation potential of thiocholine at the MC composite electrode. CV studies were also carried out to study the inhibition activity of triazophos at the composite electrode. The results show that, the peak currents decreased at the composite electrode with increase in triazophos concentration (Fig. 4). 

Pretreatment with chitosan followed wash, especially in case of after treatment by subsequent treatment with malonic with DMDHEU followed by drying and acid or DMDHEU/MgCl2-6H20 steaming at 150°C/4 min. 

Peroxide pretreatment of cotton fabrics showed better antimicrobial activity that their corresponding intact ones -The imparted antimicrobial activity was governed by the t5T)e of bio-active material and followed the decreasing order Aloe vera > chitosan > curcumin -Combination of the above-mentioned bio-active agent resulted in an enhancement in both the activity and durability of the imparted functional properties to cotton fabrics. 

Pretreatment with Na-poly-phosphate and -Co-application of chitosan with... 

Abou-Okeil, A., and Hakeim, 0. A., Effect of metal ion binding of chitosan on the printability of pretreated wool fabric, Colomtion TechnoL. 121 (2005) 41-44... 

Fouling, which causes flux decline, remains to be the biggest concern in treating dairy wastewater by membrane separation. Various pretreatment procedures have been studied to minimize this problem. In pilot-scale wastewater treatment, Sarkar et al. [187] investigated the clariflcation of dairy wastewater by chitosan treatment (10 mg L" at pH 4.0) to... 

Polyolefins, such as PE and PP, are commonly used in many applications in the biomedical sector. PE and PP can achieve biocompatible and antimicrobial properties using the suitable surface treatment [131, 132]. Many modification methods of the polymer surfaces have been employed, for example, techniques based on the plasma treatment [133]. A deposition of chitosan on the plasma-pretreated PP surface provides antifungal and antibacterial properties because chitosan exhibits an efficient antimicrobial activity [134]. If PE films were modified by a multistep process using plasma discharge, carboxylic groups and antibacterial agent can be developed over the surface. Immersion of these films into the solution of chitosan leads most likely to the adherence of a chitosan monolayer on the treated film. Small concentration of chitosan was enough for the induction of antimicrobial properties to the modified material [135]. 

Pretreated (enzymatic and enzymatic-I-hydrogen peroxide) knitted wool fabrics were treated with argon and atmospheric air plasma to improve adsorption capacity (Demir et al., 2010). After plasma treatment, a chitosan solution was appUed for antimicrobial effect. The treated fabrics were evaluated in terms of washing stabiUty as well as antimicrobial activity. The surface morphology was characterized by SEM images and Fourier transform infrared (FilR) analysis. The results indicate that the atmospheric plasma treatment had an etching effect and increased the fiinctionahty of wool surface. Atmospheric plasma treatment also enhanced the adhesion of chitosan to the surface and improved the antimicrobial activity. 

Reddy et al. (2008) cross-linked sodium alginate (SA)- and chitosan (CS)-blended membranes, pretreated with calcium chloride, with maleic anhydride for the separation of a 1,4-dioxane water mixture at 30°C by PV. The membrane performance exhibited a reduction in selectivity and an improvement in flux due to increased swelling with increasing feed water compositions. It was claimed by Reddy et al. that the membrane has a good potential for breaking the aqueous azeotrope 1,4-dioxane. 

Additional, altered, or alternative pretreatment ingredients. The aim of these is to improve on the standard uptake and fixation of dye molecules on various substrates and reduce negative environmental impacts. Examples include amino compounds on silk (Phattanarudee et al., 2009) and chitosan, as both a binder and a postprint fixation treatment (Momin, 2008). Chitosan is a biopolymer obtained from chitin, an abundant polysaccharide found in the exoskeleton of shrimp and crab and often dumped as waste. 

Katarina, R. K., Takayanagi, T., Oshita, K., Mit-suko Oshima, M., and Motomizu, S. (2008). Sample Pretreatment Using Chitosan-based Chelating Resin for the Determination of Trace Metals in Seawater Samples by Inductively Coupled Plasma-Mass Spectrometry. Analytic. Sci. 24, 1537-1544. 

Liu and Kim [71] modified the PES membrane surfaces using grafting and IP via UV/ozone pretreatment to graft PVA, PEG and chitosan on three samples of PES, and coating PVA, PEG and chitosan layers through interfacial polymerization. The description of the modification experimental design is shown in Table 2.1. 

Recently, attention has been paid to chitosan because of its favorable biological properties, such as biodegradabihty, biocompatibility, and nmi-toxicity, as weU as its physiochemical properties [2, 3]. Moreover, it has been reported that chitosan can accelerate gastric ulcer healing [4], that pretreatment with chitosan prevents ulcerogenic effect in rats [5], and that chitosan displays antimicrobial activity [6,7]. 

A new composite biosorbent has been prepared by coating chitosan onto acid treated oil palm shell eharcoal (AOPSC) and is used for the removal of chromium [142]. Bromine pretreated ehitosan was found to be promising adsorbent for lead (II) removal from water [157]. The ability of chitosan as an adsorbent for Cu (II) and Cr (VI) ions in aqueous solution was studied by Schmuhl et al. (2001). Polymer blend films of chitin and bentonite were prepared and this blended polymer was used as an adsorbent for the removal of copper and chromium from the dye effluent [169]. The alginate-chitosan hybrid gel beads were prepared and it is used to adsorb divalent metal ions [182]. 

Rajendra Dongre Minakshi Thakur Dinesh Ghugal Jostna Meshram. Bromine pretreated chitosan for adsorption of lead (II) from water. Bull. Mater. Sci. 2012, 35, 875-884. 

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