Characterization and Modification of Clay for Removal of Drinking Water Hardness

Hardness in drinking water is a major problem in domestic usage. It is important to use drinking water within the tolerance limits of hardness. Clay samples obtained from two different areas in Sri Lanka were analysed, modified, and optimized with a view to suppress the hardness in drinking water. Characterization of clay was carried out using XRD (X-ray diffraction spectroscopy), FTIR (Fourier transformed infrared spectroscopy), and SEM (Scanning electron microscope). Variation of the adsorption capacity of clay was analysed at different firing temperatures of the clay samples. XRD analysis revealed that both clay types are consisting of Kaolinite as the main constituent. The hardness adsorption efficiency and the retention of hardness adsorption in prolonged cycles has been observed when the clay is heated at different temperatures. In addition, the water hardness adsorption efficiency was enhanced by the cationic modification using sodium chloride. The results further reveals that the Freundlich isotherm is best fit for Ca2+ adsorption on both Biyagama and Deniyaya clay whereas that for the Mg2+ adsorption is Langmuir isotherm. The present study is useful to develop low-cost clay-based materials to minimize water hardness.

The adsorption of lemon yellow dye using cationic cellulose fibers from rice straw as a sustainable biosorbent in aqueous media

A biosorbent was prepared from the cellulose fibers found in rice straw through cationic modification. The effects of the dosage, pH, contact time, and initial concentration of lemon yellow dye were explored. The static adsorption results showed that cationic modification drastically improved the adsorption capacity of straw cellulose fiber. The maximum equilibrium adsorption capacity value was 137.6 mg/g and the highest removal reached 99%. The pseudo-second-order kinetic model was a good fit for the adsorption process, together with the Langmuir isotherm model. The adsorption reaction was spontaneous, and the adsorption process was an exothermic reaction, which was shown by the thermodynamic model. As the adsorption time became longer, the effluent concentration became larger until reaching equilibrium. The time was 420 min. After desorption using a dilute NaOH solution, the maximum adsorption capacity was still 36.1 mg/g and the maximum removal still reached 36.2%. The parameters calculated from the Yoon-Nelson model have a good fit with the experimental data. In short, cationic straw cellulose fiber is an effective and easy to prepare biosorbent. This work offers a new method for dye wastewater purification and solves the effective utilization of rice straw resources.

Multifunctional Hydroxyapatite/Silver Nanoparticles/Cotton Gauze for Antimicrobial and Biomedical Applications

Medical textiles have played an increasingly important protection role in the healthcare industry. This study was aimed at improving the conventional cotton gauze for achieving advanced biomedical specifications (coloration, UV-protection, anti-inflammation, and antimicrobial activities). These features were obtained by modifying the cotton gauze fabrics via in-situ precipitation of hydroxyapatite nanoparticles (HAp NP), followed by in-situ photosynthesis of silver (Ag) NPs with ginger oil as a green reductant with anti-inflammation properties. The HAp-Ag NPs coating provides good UV-protection properties. To further improve the HAp and Ag NPs dispersion and adhesion on the surface, the cotton gauze fabrics were modified by cationization with chitosan, or by partial carboxymethylation (anionic modification). The influence of the cationic and anionic modifications and HAp and Ag NPs deposition on the cotton gauze properties (coloration, UV-protection, antimicrobial activities, and water absorption) was thoroughly assessed. Overall, the results indicate that chemical (anionic and cationic) modification of the cotton gauze enhances HAp and Ag NPs deposition. Chitosan can increase biocompatibility and promotes wound healing properties of cotton gauze. Ag NP deposition onto cotton gauze fabrics brought high antimicrobial activities against Candida albicans, Gram-positive and Gram-negative bacteria, and improved UV protection.

The Study of Cationic Modification of Welan Gum

In the present study, welan gum (WG) was modified with a quaternary amine group producing cationic welan gum (CWG) to enhance its thermal and viscosity properties. N-(3-chloro-2-hydroxypropyl) trimethyl ammonium chloride (CHPTAC) was used as the source of the quaternary amine group. The effect of CHPTAC amount in the presence of NaOH was investigated and analyzed using Fourier transform infrared (FTIR), Field emission scanning electron microscope (FESEM), thermal and viscosity analysis. The viscosity results were increases as the amount of CHPTAC increased. From the thermal analyses, it is observed that the CWG has better thermal resistance compared to WG. This study showed that modification of WG by attaching quaternary amine group on the hydroxyl group is promising for the exploration of the high-temperature reservoir.

Surfactant-Modulation of the Cationic-Polymer-Induced Aggregation of Anionic Particulate Dispersions

Commodity formulations contain many chemically distinct components and their mutual interactions define the beneficial characteristics of the formulation. Mixing oppositely charged polymers and surfactants invariably induces macroscopic phase separation, to a degree dependent on the prevailing polymer and surface charge densities, and the interaction can be modulated by added ionic surfactants. Here, it is shown that a general universality exists between the charge present on a series of cationic-modified cellulose polymers—the charge being controlled either by the degree of cationic modification of the polymer itself or through the subsequent level of anionic surfactant binding—and its capacity to remove anionic colloidal material from solution, be that silica particles or polystyrene-butadiene lattices. Particulate material not removed from solution bears no adsorbed polymer, i.e., the particle surface is bare. Addition of nonionic surfactant does not negate this universality, implying that the nonionic surfactant is largely a spectator molecule or structure (micelle) in these systems, and that the dominant force is an electrostatic one.

Cell proliferation induced by modified cationic dextran

The interaction between oppositely charged membranes and polycations causes cell aggregation, loss of membrane fluidity, and membrane degeneration and may cause an increase of its permeability. Unfortunately, the interaction is the reason why the use of polycations in medicine is severely limited. Therefore, in this paper, we share our observations related to the action of 40-kDa dextran modified using glycidyltrimethylammonium chloride, resulting in increased fibroblast cell proliferation. Using viability and proliferation tests [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide, crystal violet, 3H-thymidine incorporation], we have observed that cationic dextran derivatives exert a positive impact on nonepithelial cell proliferation in vitro. This phenomenon has been noted for human and mouse fibroblasts and several other nonepithelial cell lines. However, the effect seems to be most pronounced for fibroblast cell lines. The presented studies allow to examine the impact of the polymer structure and the methods of its cationic modification on this newly observed phenomenon. The observation is unique because positively charged macromolecules usually exhibit high toxicity in all cell types in vitro.