Preparation of Some Cationic Starches Using the Dry Process

Novel Cellulose Derivatives Containing Metal (Cu, Fe, Ni) Oxide Nanoparticles as Eco-Friendly Corrosion Inhibitors for C-Steel in Acidic Chloride Solutions

Novel environmentally-friendly corrosion inhibitors based on primary aminated modified cellulose (PAC) containing nano-oxide of some metals (MONPs), for instance iron oxide nanoparticles (Fe₃O₄NPs), copper oxide nanoparticles (CuONPs), and nickel oxide nanoparticles (NiONPs), were successfully synthesized. The as-prepared PAC/MONPs nanocomposites were categorized using Fourier transform infrared spectroscopy (FT-IR), transmission electron microscope (TEM), field-emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), and selected area diffraction pattern (SAED) techniques. The data from spectroscopy indicated that successful formation of PAC/MONPs nanocomposites, as well as the TEM images, declared the synthesized PAC/Fe₃O₄NPs, PAC/CuONPs, and PAC/NiONPs with regular distribution with particle size diameters of 10, 23 and 43 nm, respectively. The protection performance of the as-prepared PAC and PAC/MONPs nanocomposites on the corrosion of C-steel in molar HCl was studied by the electrochemical and weight-loss approaches. The outcomes confirmed that the protection power increased with a rise in the [inhibitor]. The protection efficiency reached 88.1, 93.2, 96.1 and 98.6% with 250 ppm of PAC/CuONP, PAC/Fe₃O₄NPs, and PAC/NiONPs, respectively. PAC and all PAC/MONPs nanocomposites worked as mixed-kind inhibitors and their adsorption on the C-steel interface followed the isotherm Langmuir model. The findings were reinforced by FT-IR, FE-SEM and EDX analyses.

In-Situ Deposition of Metal Oxides Nanoparticles in Cellulose Derivative and Its Utilization for Wastewater Disinfection

The target of this work is to investigate and assess the utilization of the synthesized in-situ deposition of metal oxide nanoparticles such as nano-nickel oxide (nNiO), nanocopper oxides (nCuO) and nanoiron oxides (nFe₃O₄) in aminated cellulose (Acell), as a protected and compelling antibacterial channel of contamination from domestic wastewater. The prepared Acell and nNiO/Acell, nCuO/Acell and nFe₃O₄/Acell nanocomposites were characterized by field emission-scanning electron microscopy (FE-SEM), Fourier transform-infrared spectroscopy (FT-IR), energy-dispersive X-ray spectroscopy, transmission electron microscopy (TEM), selected area diffraction pattern (SAED) and X-ray diffraction techniques (XRD). TEM declared the synthesis of nNiO, nCuO and nFe₃O₄ with regular size of 10, 23 and 43 nm, correspondingly. The antibacterial impact of both nNiO/Acell, nCuO/Acell and nFe₃O₄/Acell nanocomposites was inspected against Gram-positive microorganisms (Enterococcus faecalis, Staphylococcus aureus) and Gram-negative microbes (Escherichia coli, Salmonella typhi) utilizing agar disk diffusion routes. Furthermore, the ability of the synthesized nanocomposites as sterilizers for optional domestic wastewater was studied. The data for the disk diffusion obtained revealed that nFe₃O₄/Acell had a greater antibacterial impact than nCuO/Acell and nNiO/Acell. In addition, the purification of domestic wastewater utilizing 1.0 mg of nFe₃O₄, nCuO and nNiO in 1 gm of Acell was accomplished by killing 99.6%, 94.5% and 92.0% of total and fecal coliforms inside 10 mins, respectively.

Coagulation/flocculation in dewatering of sludge: A review

Sludge disposal is an integral part of wastewater treatment systems, and its cost usually accounts for more than half of the total operation cost. Sludge disposal technology is facing challenges and opportunities simultaneously and can still be improved. Sludge dewatering is an essential process in sludge disposal, and it is important for the effective reduction of the final processing cost. Coagulation/flocculation is a relatively mature, cost-effective, user-friendly sludge dewatering technology. In this work, coagulation/flocculation and their combinations with other pretreatments, including dewatering mechanisms, are reviewed. Various coagulants/flocculants used in sludge dewatering, including inorganic coagulants, organic synthetic and natural polymeric flocculants, and bioflocculants, are introduced in detail because coagulants/flocculants are the key in coagulation/flocculation. The different factors that influence the dewatering performance of these coagulants/flocculants are also presented briefly. Moreover, aiming at the complicated composition of sludge and its treatment difficulty, the prospects and technical developments of coagulation/flocculation in sludge dewatering are discussed.

Synthesis of Carboxymethyl Starch with High Degree of Substitution by a Modified Dry Process

Granular carboxymethyl starch (CMS) with high degree of substitution (DS) was synthesized using a modified dry process. The carboxymethylation reaction was carried out with granular potato starch, solid NaOH and sodium monochloroacetate (SMCA). The effects of reaction temperature, reaction time, molar ratio of NaOH and SMCA to starch on the degree of substitution (DS) and the reaction efficiency (RE) of CMS were investigated. High DS up to 0.78 was obtained for reaction at 323 K for 6 h with molar ratio of NaOH and SMCA to starch being 2:2:1. CMS was characterized by Fourier transform infrared spectrophotometer and scanning electron microscopy.

Influence of substituent type on properties of starch derivates

The subject of the study was investigation of influence of substituent type on the properties of starch derivates in diluted solutions. Three samples were prepared: two anionic (carboxymethyl starch, CMS) and one cationic starch (KS). Starch derivates were synthesized in two steps. The first step was preparation of alkali starch by the addition of sodium-hydroxide to the starch dispersed in ethanol or water. In the second step, the required amount of sodium monocloracetate or 3-chloro-2-hydroxypropyl-threemethylamonium chloride was added to the obtained alkali starch in order to prepare CMS or KS, respectively. The degree of substitution of carboxymethyl starch was determined by back titration method, and the degree of substitution of cationic starch was determined by potentiometric titration. The degrees of substitution of prepared samples were: 0.50 (assigned as CMS-0.50) and 0.70 (assigned as CMS-0.70) for carboxymethyl starch and 0.30 (assigned as KS-0.30) for cationic starch. The properties of starch derivatives in dilute solutions were investigated by the methods of static and dynamic light scattering. Aqueous solutions of sodium chloride of different concentrations were used as solvent. The values of the mass average molar mass, MW, radius of gyration, Rg, and second virial coefficient, A2, were determined for all samples together with hydrodynamic radius, Rh. Molar masses of the samples were: 5.06?106, 15.4?106 and 19.2?106 g/mol for CMS-0.50, CMS-0.70 and KS-0.30, respectively. The samples, CMS-0.70 and KS-0.30 had similar molar mass and hydrodynamic radius, but radius of gyration of KS-0.30 was smaller then radius of gyration of CMS-0.70 at all sodium chloride concentrations. Consequently, ? value for KS-0.30 was smaller then for CMS-0.70, as a result of more compact architecture of KS-0.30 then of CMS-0.70. Kratky graph confirmed this result. For all samples, radius of gyration and hydrodynamic radius decreased with increasing of sodium chloride concentration, but decrease of the radius was greater for CMS-0.50 then for other two samples due to its significantly lower molar mass. On the other hand, change of both radius of gyration and hydrodynamic radius of CMS-0.70 and of KS-0.30 with increasing sodium chloride concentration were similar. It can be concluded that the decrease of both Rg and Rh with increasing sodium chloride concentration in water depends far more on molar mass than on degree of substitution.

Enzyme-Aided Investigation of the Substituent Distribution in Cationic Potato Amylopectin Starch

The distribution of substituents along the polymer chain in cationic potato amylopectin starch, modified in solution, granular slurry, or dry state, was investigated. The starch derivatives were successively hydrolyzed by different enzymes, followed by characterization of the hydrolysis products obtained by means of electrospray mass spectrometry (ESI-MS) and matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). ESI-MS and MALDI-MS were proved to be appropriate techniques for identification of the substituted hydrolysis products, for which there are no standard compounds available. No highly substituted oligomers were found in the hydrolysates, which was taken as an indication of a more or less homogeneous distribution of cationic groups in the amylopectin molecules. Furthermore, from the results obtained it was suggested that the enzymes cleave glucosidic linkages only between unsubstituted glucose units and, preferentially, linkages in sequences containing more than two adjacent unsubstituted units. The determination of the amount of unsubstituted glucose produced from every successive hydrolysis step revealed slight differences between the different starch samples with respect to the homogeneity of the substitution pattern. Among the three samples under investigation, starch cationized in solution was found to have the most and dry-cationized starch the least homogeneous distribution of substituents.

Synthesis of starch derivatives with labile cationic groups

A new route to starch derivatives bearing hydrolyzable cationic groups was developed. This was based on reacting starch compounds with betaine derivatives in the presence of diisopropylcarbodiimide and 4-dimethylaminopyridine as coupling reagents in an aprotic polar solvent. Water-soluble starches with a perfectly controlled degree of substitution were thus obtained which were fully characterized by infrared, 1H and 13C spectroscopy and viscosity measurements. The cationic groups grafted on the polysaccharides are shown to hydrolyze slowly upon storage at room temperature.

The substitution pattern in cationised and oxidised potato starch granules

The distribution pattern of substituents within the granules and the components of two cationised and two oxidised potato starches was studied. The level of crystallinity in wet-cationised (WC) and hypochlorite oxidised (HO) starch granules was similar to that of native starch granules but lower in dry-cationised (DC) and peroxide oxidised (PO) granules. However, the melting temperature of DC granules remained similar to native granules but was decreased in the other samples. With all modified starches, the initial rate of acid hydrolysis (lintnerisation) was increased compared to native granules. The degree of substitution decreased only slightly in WC granules after the lintnerisation, whereas virtually all the substituted glucosyl units in DC starch were hydrolysed already at initial stages. The decrease of substituents in the HO and PO starches was intermediate. The starches were partly resistant to the action of isoamylase and the successive beta-amylolysis, suggesting that substituents were found both close to the branches and near the nonreducing ends in the amylopectin component. It is suggested that the DC starch was preferentially cationised at the surface of the granules, whereas WC and oxidised starches were modified throughout the granules.