Lignin based microspheres for effective dyes removal: Design, synthesis and adsorption mechanism supported with theoretical study.

Multifunctional lignin bio-based adsorbent, b-LMS, was obtained via inverse copolymerization in the suspension of acryloyl modified kraft lignin (KfL-AA) and bio-based trimethylolpropane triacrylate (bio-TMPTA). Morphological and structural characterization of KfL-AA and b-LMS was performed using BET, FTIR, Raman, NMR, TGA, SEM, and XPS techniques. The b-LMS microspheres with 253 ± 42 µm diameters, 69.4 m2 g-1 surface area, and 59% porosity efficiently adsorb Malachite Green (MG), Tartrazine (T), and Methyl Red (MR) dye. The influence of pH, pollutant concentration, temperature, and time on the removal efficiency was studied in a batch mode. Favorable and spontaneous processes with high adsorption capacities e.g. 116.8 mg g-1 for MG, 86.8 mg g-1 for T, and 68.6 mg g-1 for MR indicate the significant adsorptive potential of b-LMS. Results from diffusional and single mass transfer resistance studies indicate that pore diffusion is a rate-limiting step. Theoretical calculations confirmed a higher affinity of b-LMS to cationic dye MG compared with an anionic and neutral one, i.e. T and MR, respectively. The data fitting from a flow system, using semi-empirical equations and Pore Surface Diffusion Modelling (PSDM) provided breakthrough point determination. The results from the desorption and competitive adsorption study proved the exceptional performance of b-LMS. Moreover, sulfation of b-LMS, i.e.production of b-LMS-OSO3H, introduced high-affinity sulfate groups with respect to cationic dye and cations. Developed methodology implements the principle of sustainable development and offers concept whose results contribute to the minimization of environmental pollution.

Structural Characterization of Nanocellulose/Fe3O4 Hybrid Nanomaterials.

The rise of innovation in the electrical industry is driven by the controlled design of new materials. The hybrid materials based on magnetite/nanocellulose are highly interesting due to their various applications in medicine, ecology, catalysis and electronics. In this study, the structure and morphology of nanocellulose/magnetite hybrid nanomaterials were investigated. The effect of nanocellulose loading on the crystal structure of synthesized composites was investigated by XRD and FTIR methods. The presented study reveals that the interaction between the cellulose and magnetic nanoparticles depends on the nanocellulose content. Further, a transition from cellulose II to cellulose I allomorph is observed. SEM and EDS are employed to determine the variation in morphology with changes in component concentrations. By the calculation of magnetic interactions between adjacent Fe3+ and Fe2+ ions within composites, it is determined that ferromagnetic coupling predominates.

Novel amino-functionalized lignin microspheres: High performance biosorbent with enhanced capacity for heavy metal ion removal.

Novel highly effective amino-functionalized lignin-based biosorbent in the microsphere geometry (A-LMS) for removal of heavy metal ions, was synthesized via inverse suspension copolymerization of kraft lignin with poly(ethylene imine) grafting-agent and epoxy chloropropane cross-linker. Optimization of A-LMS synthesis, performed with respect to the quantity of sodium alginate emulsifier (1, 5 and 10 wt%), provides highly porous microspheres A-LMS_5, using 5 wt% emulsifier, with 800 ± 80 µm diameter, 7.68 m2 g-1 surface area and 7.7 mmol g-1 of terminal amino groups. Structural and surface characteristics were obtained from Brunauer-Emmett-Teller method, Fourier Transform-Infrared spectroscopy, scanning electron microscopy, X-ray photoelectron spectroscopy and porosity determination. In a batch test, the influence of pH, A-LMS_5 dose, temperature, contact time on adsorption efficiency of Ni2+, Cd2+, As(V) and Cr(VI) ions were studied. The adsorption is spontaneous and feasible with maximum adsorption capacity of 74.84, 54.20, 53.12 and 49.42 mg g-1 for Cd2+, Cr(VI), As(V) and Ni2+ ions, respectively, obtained by using Langmuir model. Modeling of kinetic data indicated fast adsorbate removal rate with pore diffusional transport as rate limiting step (pseudo-second order model and Weber-Morris equations), thus further confirming high performances of produced bio-adsorbent for heavy metal ions removal.

Copper-tolerant yeasts: Raman spectroscopy in determination of bioaccumulation mechanism.

Modern, efficient, and cost-effective approach to remediation of heavy metal-contaminated soil is based on the application of microorganisms. In this paper, four isolates from agricultural and urban contaminated soil showed abundant growth in the presence of copper(II) sulfate pentahydrate (CuSO4·5H2O) up to 2 mM. Selected yeasts were identified by molecular methods as Candida tropicalis (three isolates) and Schwanniomyces occidentalis (one isolate). C. tropicalis (4TD1101S) showed the highest percentage of bioaccumulation capabilities (94.37%), determined by the inductively coupled plasma optical emission spectrometry (ICP-OES). The Raman spectra of C. tropicalis (4TD1101S) analyzed in a medium with the addition of 2 mM CuSO4·5H2O showed certain increase in metallothionein production, which represents a specific response of the yeast species to the stress conditions. These results indicate that soil yeasts represent a potential for practical application in the bioremediation of contaminated environments.