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The adsorption of metal ions from increasing concentrations in aqueous solutions by modified straw lignin Protobind 1000 was studied. The effect of metallic ion concentrations (from 20.72 to 207.2 mg·L-1 for Pb2+ and from 6.538 to 65.38 mg·L-1 for Zn2+) and contact time (30, 60 and 90 minutes) were studied at pH = 6 and 200C. Langmuir and Freundlich isotherm equations were applied to assess equilibrium data and the kinetics of the adsorption processes were analysed using Lagergren pseudo first order and Ho&McKay pseudo second order models. The results show that the adsorption processes reached equilibrium after 90 minutes, but similar values were registered after 60 minutes. The Freundlich isotherm described the process better, denoting chemisorption with the formation of ion-lignin complex structures. The Ho&McKay model fit the adsorption data better with regression coefficients equal to 1 compared to the Lagergren model, where the regression factors varied between 0.72 and 0.95. For the maximum concentration of lead solution and the longest adsorption time of 90 minutes, the Ho&McKay model predicted an equilibrium capacity qe of 13.1406 mg·g-1 compared to the 13.1398 mg·g-1 obtained. For zinc adsorption, the same maximum concentration and time were considered, and the pseudo-second order model predicted a qe of 12.6743 mg·g-1 compared to the obtained value of 12.6714 mg·g-1. The uptake of lead was greater on 0.15 g of adsorbent (a maximum of 27.23 mg·g-1) than the zinc uptake (a maximum of 8.28 mg·g-1), for all analysed concentrations.

In this study, the adsorption of Pb2+ and Zn2+ ions from aqueous solutions onto lignin obtained from unmodified Sarkanda grass was analyzed. To ensure optimal process conditions, the retention of lead and zinc ions was tested at different experimental parameters (pH of the initial solution and adsorbent, the dose of adsorbent, the concentration of aqueous solutions and contact time). The experimental results have been interpreted using the classic Langmuir and Freundlich isotherm models, as well as two kinetic models (the Lagergren pseudo-first order and the Ho and McKay pseudo-second order models). Based on the analysis of the experimental data, it has been concluded that unmodified Sarkanda grass lignin can be recommended as an efficient alternative, considering its practical applicability, in the retention of Pb2+and Zn2+ ions from aqueous solutions, both in terms of the amount of adsorbate and pollutant species retained, as well as in terms of adsorption time.

In the present work, precipitated calcium carbonate (PCC) and carboxymethyl chitosan (CMC) were prepared to obtain new hybrid materials used in papermaking. In the first step, occurred the precipitation of CaCO3 in solution containing CMC at different levels (0.5%, 1%, and 1.5%). In the second step, PCC–CMC hybrid material (25%) was added to pulp suspension, and the sheets were made. The effect of PCC–CMC on paper properties (mechanical and optical) was systematically investigated. Breaking length, the brightness and opacity of the sheets obtained with the PCC–CMC material were better than the sheets fabricated with the unmodified PCC at similar levels of content.

The present research reports the efficient synthesis of mono- and di-(aminophenyl)porphyrins and their metalation with Zn(II) using microwave irradiation. The subsequent reaction of amino-functionalized porphyrins with siloxane moieties bearing epoxy or carboxyl functional groups provided four new porphyrin-modified siloxanes. The structure of the resulting derivatives was established by 1H-NMR and MALDI-TOF-MS. The optical properties of the porphyrin chromophores were preserved, as proven by comparing the absorption and emission spectra of the initial porphyrins to those of the porphyrin-modified siloxanes.

The present paper presents the preparation and characterization of Ni complex of a guanidine functionalized trisiloxane as a model compound for polysiloxanes supported metal complexes. The structures of the ligand and its Ni complex are elucidated by theoretical calculations using semi-empirical PM6 and DFT methods, and experimentally confirmed by IR, UV, NMR, SEM and EDX. Thus, a 1/1 ligand/Ni complex with a tetragonal structure was established. As proved by ATG and DSC analysis, the Ni complex is stable up to about 170 °C and is characterized by a Tg value of 25 °C in dry state. Dielectric measurements revealed a conductivity of 5.6 × 10−7 S cm−1 at 25 °C for the Ni complex, about ten times higher as compared to that of the ligand, due to the reduction of the conduction activation energy induced by the presence of the metal.

In the present paper, aspects concerning the obtained and characterization of additive systems used for maximizing filler retention, and the effects on paper properties, were investigated. The effects of retention additives over properties of paper, containing fibers from in-situ loading (IS-CCP), were analyzed against the effects of additives over properties of paper containing fibers from conventional loading, obtained by the addition of calcium carbonate in precipitated form (CCP). The physico-mechanical properties were analyzed by various analyses and investigations: calcium carbonate content, X-ray diffraction, scanning electron microscopy (SEM) images, optical and mechanical properties, in order to develop the best systems of retention additives for obtaining higher retention loads for making paper with high content of nano-filler material. The obtained results reveal that at the same level of calcium carbonate content, all paper samples with in-situ loading had higher the optical and mechanical properties than the paper obtained by conventional loading in all cases the additives studied. For all studied properties, nanoparticles had a positively influence over paper properties.

Aquatic environments are often contaminated with various compounds, with potential toxicity towards aquatic organisms, which may enter the food chain. Azo dyes are used in various industries and contamination of waters has been reported. The present paper assesses the toxicity of the synthetic, water soluble Congo Red dye towards Lemna minor from a physiological and cytogenetical point of view. The dye was tested in 5-5000 ppm concentrations. Total frond surface, root growth and fresh mass reductions were registered from 5 ppm dye concentration, with a concentration-dependent response and calculated EC50 of 1530 ppm. Plant growth was completely inhibited above 2500 ppm. Dye accumulation was observed in tissues, along with necrosis formation. Chlorophyll a contents decreased, while carotenoid contents increased above 2500 ppm. Significant inhibition of PSII efficiency was recorded above 1000 ppm. Mitotic indices were decreased at 5 and 1000 ppm dye and were 0 at 5000 ppm. The number of chromosomal aberrations significantly increased at 5 and 1000 ppm dye. The growth medium was decontaminated up to 56% at 250 ppm dye concentration by Lemna plants. Congo Red azo dye presented toxicity towards Lemna minor, from a physiological and cyotgenetical point of view, especially at higher concentrations. In the same time, a phytoremediation potential of duckweed with respect to the tested dye was demonstrated.

The present research reports on the synthesis and properties of mesoporous carbon (MC) surface with functionalized aminopropyl-polydimethylsiloxane (AP-PDMS). The aim of MC surface modification was focused on the improvement of its electrical properties (EC electric conductivity), as well as its sorption capacity for cesium ions. In order to anchor AP-PDMS molecules, an intermediate functionalization step of the MC surface with carboxylic groups was carried out. In this respect, two different methods, namely: (i) sonication in the presence of the hydrogen peroxide (MC-COOH) and (ii) gas-plasma activation (MCA) have been considered for carbon surface oxidation. Further, AP-PDMS component was crosslinked to the COOH-reached carbon surface. Fourier transform infrared spectroscopy (FT-IR) and energy dispersion spectroscopy (EDX) were used to confirm the presence of AP-PDMS molecules on MC surface. Morphological and textural properties of the obtained composites have been investigated by using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and nitrogen adsorption–desorption measurements, as well as their electrical properties (EC). The obtained results reveal the grafting of silane-containing component onto MC surface, an improved electrical conductivity of the synthesized composites toward MC sample. Also, the functionalization proved to be efficient in the sorption process of the cesium ions from aqueous solutions, despite the fact that the materials surface became hydrophobic.

Co(II), Cd(II) and Rh(III) complexes with 2-(1H-1,2,4-triazol-3-yl)pyridine (Htzp) as ligand were synthesized and investigated. The neutral mononuclear complexes with a generic [M(tzp)n] structure have been prepared from Htzp and corresponding transition metals chlorides at 2:1 and 3:1, respectively molar ratios in H2O–EtOH. The resulted crystalline complexes were investigated through magnetic and molar conductivity measurements, elemental analysis, FT-IR, mass spectroscopy, thermal analysis, UV-Vis and P-XRD. The experiments indicate that Htzp acts as bidentate anionic ligand, [Co(tzp)2]·1.5H2O and [Cd(tzp)2] are in the tetragonal coordination, whereas six coordinate octahedral [Rh(tzp)3]·H2O complex undergoes a weak tetragonal distortion. In case of Co(II) complex, an interesting feature was revealed through fluorescence spectroscopy, as the fluorescent emission intensity of the free ligand is dependent on the Co(II) solution content. Through complexation, the fluorescence is gradually quenched according to the Co(II) aqueous solution content, which may recommend it as a method of detection of Co(II) presence in waste water.

The UV absorption spectra of polyhydrosilanes are investigated with the purpose to obtain a model that correlates specific aspects of the electronic spectra to the polymer chemical structure. For this purpose polysilanes with a well defined chemical structure were synthesized in similar reaction conditions. UV investigations have been carried out to obtain the profile of the synthesized polysilane electronic spectra and identify the effects induced by both structural and conformational changes. Molecular modeling calculations were then correlated with the experimental results in order to connect the electronic system to the polysilane structure. Such a method is useful to study polysilanes with complex structures where parts of the polymeric architecture should have a specific influence on the conjugated electrons system.

Construction and demolition wastes (C&DW) are usually recognized as not dangerous, but their accumulation can generate serious environmental problems. In spite of C&DW high potential to be reused/recycled, the practical procedures need to be assessed in terms of environmental consequences. The objective of this study is to quantify the environmental impacts of C&DW recycling/reuse, specifically in the production of aggregate 0/30 mm, comparative to those generated during the natural inert processing, in terms of global impacts addressing the whole process and for each technological phase. The analysis was carried out using Life Cycle Assessment methodology, assisted by SimaPro software, and based on primary data collected directly from the Italian Emilia Romagna region. Three methods were used for impact quantification: Eco-Indicator 99, EDIP/UMIP and Cumulative Energy Demand. The analysis revealed that the environmental impacts generated by C&DW recycling/reuse accounting for about 40% of the impacts induced by natural inert processing.

The goal of this study was to analyze the effects of cellulose fibers loading by precipitation in-situ of calcium carbonate over the properties of printing paper obtained from mixtures of the softwood and hardwood fibers. The effects of fibers with in-situ loading were analyzed comparatively with conventional paper loading respectively, by adding precipitated calcium carbonate into fiber stock. The effectiveness of the methods was evaluated by various analyses and investigations: calcium carbonate content, Scanning electron microscope (SEM) images, X-ray diffraction, optical and mechanical properties of the paper sheets. The evaluation of the effects on paper properties led to the conclusion that, at the same filler content, the in-situ loading method gives higher opacity and brightness than conventional methods. The utilization of cellulose fibers with in-situ loading as additive, shown as a modification of the ratio between fibers with in-situ loading and fibers without loading, regardless of whether they are softwood or hardwood fibers, allowed us to optimize printing paper properties, especially regarding the relationship between optical and strength properties.

The effect of synthesis conditions on sorptive properties of glycerol-derived mesoporous carbon materials were studied. Sorption properties of the synthesized carbon-based materials regarding to different adsorbate molecules, as well as water vapors, phenol and methylene blue molecules were analyzed. The sorption capacity of the synthesized mesoporous carbons depends upon synthesis conditions, namely upon pyrolyzing temperature and carbon precursor to silica weight ratio, being determined by the nature of the adsorbate molecule and the chemical and structural properties of carbon-based mesoporous material. The templated mesoporous carbons were synthesized using two different glycerol/silica weight ratios (0.5 and 1) and were pyrolyzed at various temperatures (800 degrees C and 1000 degrees C) to study changes in their textural, structural, morphological and chemical surface properties, as well their sorptive properties. The obtained data showed that both considered parameters, glycerol/silica weight ratio and pyrolysis temperature, are important factors in developing the carbon properties. The variation of above mentioned parameters conduct to a progressive deterioration of the carbon structure, associated with structure shrinking and pore walls breaking. Especially significant changes in the structural properties of the studied mesoporous carbon materials occurred for those heated at 1000 degrees C, which manifested themselves in a loss of the total pore volume. It was found that the mesoporous carbons exhibited better thermal stability reflected by the presence of residual mesopores and/or nanostructure ordering. The studies show that the adsorption of methylene blue and phenol onto glycerol-derived mesoporous carbon materials is influenced by their surface chemistry given by the synthesis conditions.

The present research reports the synthesis of poly-N-isopropylacrylamide / mesoporous carbon composites, prepared by radical polymerization of N-isopropylacrylamide inside mesoporous carbon pores functionalized with carboxylic groups. The deposition of poly-N-isopropylacrylamide on mesoporous carbon was confirmed by FT-IR spectroscopy, TEM, N2-sorption measurements. The mesoporous carbon material was found to adsorb vitamin B2 from aqueous solution at room temperature. The obtained composite, poly-N-isopropylacrylamide / mesoporous carbon, exhibited a higher adsorption capacity for vitamin B2 as compared to un-functionalized mesoporous carbon sample, due to hydrogen bonding between carbonyl groups of poly-Nisopropylacrylamide immobilized on the mesoporous carbon surface and amino groups of vitamin B2 molecules.