Hexametaphosphate cross-linked chitosan beads for the eco-efficient removal of organic dyes: Tackling water quality.

There is an increasing trend of developing various low-cost grafted natural amino polysaccharides for the biosorptive removal of noxious dye effluents like Malachite green (MG) and anionic Reactive Red-195 (RR-195) dyes from aqueous solution. Chemically cross-linked chitosan microsphere (CTS-HMP), a promising non-toxic biosorbent possessing high charge density and thermal stability was prepared by using hexametaphosphate as ionic cross-linker. Batch biosorption experiments were carried out under different temperatures (298, 308 and 318 K), pH (2.0-10.0), initial concentrations (25-250 mg L-1), adsorbent dosage (0.01-0.1 g) and contact times (0-180 min) to understand the optimum experimental conditions and simultaneously evaluate the adsorption isotherms and kinetics of CTS-HMP. Biosorption equilibrium was established in 120 and 60 min for MG and RR-195 removal process. The pseudo-equilibrium process was best described by the pseudo-second-order kinetic (R2 ≥ 0.98), Freundlich and Temkin isotherm model (R2 ≥ 0.90). The removal rate of MG and RR-195 gradually increased (69.40 and 148 mg g-1) at 250 mg L-1 of initial concentration till 100 and 50 min of contact period in a single contaminant system, though the removal efficiency of acid dye was ~2 times higher compared to basic dye under optimum conditions (p < 0.05; t-test). Thermodynamic parameters indicated exothermic (MG) and endothermic (RR-195) nature of spontaneous dye removal. The activation energy of sorption (Ea) was <50 kJ mol-1 which highlighted the importance of physical adsorption process. Therefore, the obtained results clearly validate the sustainable utilization of CTS-HMP as a promising functionalized chitosan microparticles/agent for removing dye effluents from the contaminated aqueous phase.

Pyrimidine-based pyrazoles as cyclin-dependent kinase 2 inhibitors: Design, synthesis, and biological evaluation.

A series of new pyrimidine-pyrazole hybrid molecules were designed as inhibitors of cyclin-dependent kinase 2. Designed compounds were docked using Glide and the compounds showing good score values and encouraging interactions with the residues were selected for synthesis. They were then evaluated using CDK2-CyclinA2 enzyme inhibition by a luminescent ADP detection assay. We show that of the 26 compounds synthesized and evaluated, at least 5 compounds were found to be highly potent (IC50  < 20 nm); which can be further optimized to have selectivity over other kinase isoforms.

Adsorption of lead (II) ions onto novel cassava starch 5-choloromethyl-8-hydroxyquinoline polymer from an aqueous medium.

Adsorption of lead (II) ions onto cassava starch 5-choloromethyl-8-hydroxyquinoline polymer (CSCMQ) was investigated with the variation in the parameters of pH, contact time, lead (II) ions concentration, temperature and the adsorbent dose. The Langmuir and Freundlich models have been applied. CSCMQ was characterized by Fourier transform infrared spectroscopy and scanning electron microscopy. Results showed that the adsorption process was better described by the Langmuir model. Adsorption kinetics data obtained for the metal ions sorption were investigated using pseudo-first-order, pseudo-second-order and intraparticle diffusion model. The maximum adsorption capacities (qm) were 46.512, 43.859 and 42.735 mg/g at 25, 35 and 45 °C, respectively. The dynamical data fit well with the second-order kinetics model. The results indicate that CSCMQ could be employed as low-cost material for the adsorption of Pb(II) ions from aqueous medium.

Adsorptive amputation of hazardous azo dye Congo red from wastewater: a critical review.

Increasing amount of dyes in an ecosystem has propelled the search of various methods for dye removal. Amongst all the methods, adsorption occupies a prominent place in dye removal. Keeping this in mind, many adsorbents used for the removal of hazardous anionic azo dye Congo red (CR) from aqueous medium were reviewed by the authors. The main objectives behind this review article are to assemble the information on scattered adsorbents and enlighten the wide range of potentially effective adsorbents for CR removal. Thus, CR sorption by various adsorbents such as activated carbon, non-conventional low-cost materials, nanomaterials, composites and nanocomposites are surveyed and critically reviewed as well as their sorption capacities are also compared. This review also explores the grey areas of the adsorption performance of various adsorbents with reference to the effects of pH, contact time, initial dye concentration and adsorbent dosage. The equilibrium adsorption isotherm, kinetic and thermodynamic data of different adsorbents used for CR removal were also analysed. It is evident from a literature survey of more than 290 published papers that nanoparticle and nanocomposite adsorbents have demonstrated outstanding adsorption capabilities for CR. Graphical abstract ᅟ.

Adsorptive removal of nickel(II) ions from aqueous environment: A review.

Among various methods adsorption can be efficiently employed for the treatment of heavy metal ions contaminated wastewater. In this context the authors reviewed variety of adsorbents used by various researchers for the removal of nickel(II) ions from aqueous environment. One of the objectives of this review article is to assemble the scattered available enlightenment on a wide range of potentially effective adsorbents for nickel(II) ions removal. This work critically assessed existing knowledge and research on the uptake of nickel by various adsorbents such as activated carbon, non-conventional low-cost materials, nanomaterials, composites and nanocomposites. The system's performance is evaluated with respect to the overall metal removal and the adsorption capacity. In addition, the equilibrium adsorption isotherms, kinetics and thermodynamics data as well as various optimal experimental conditions (solution pH, equilibrium contact time and dosage of adsorbent) of different adsorbents towards Ni(II) ions were also analyzed. It is evident from a literature survey of more than 190 published articles that agricultural solid waste materials, natural materials and biosorbents have demonstrated outstanding adsorption capabilities for Ni(II) ions.

Synthesis and antimicrobial studies of s-triazine based heterocycles.

In an effort to discover new candidates with improved antimicrobial activities we report here the synthesis and in vitro biological evalution of various series of 2-(N-methylamino)-4-(N,N-dimethylamino)-6-(arylthioureido)-s-triazine (5a-j) and (N-methylamino)-4-(N,N-dimethylamino)-6-(arylureido)-s-triazine (6a-j). All the synthesized compounds were screened in vitro for their antibacterial activity against two different gram-positive bacteria (S. aureus, B. subtilis) and two different gram-negative bacteria (P. aeruginosa, E. coli) using the broth dilution method.