Environmentally friendly copolymeric beads of Chlorella vulgaris and poly(methacrylamide) grafted aliginic acid di‐block copolymers for biosorption of zinc ions

The synthesis of biodegradable environmentally friendly copolymeric beads for water treatment biosorption processes is demonstrated. The synthesized poly(methacrylamide) grafted aliginic acid copolymers were characterized using ¹H NMR, Fourier transform infrared spectroscopy, TGA and SEM. The di‐block copolymers showed a morphological change from two‐dimensional layer‐by‐layer structures to three‐dimensional well‐compacted wrinkles as grafting efficiency increased. The copolymeric beads were formed from the di‐block copolymer and algae crosslinked with 5% calcium ions (w/w). These copolymeric beads were then subjected to biosorption investigations for zinc ions as a model heavy metal ion at different pH values and stirring time periods. Batch adsorption experiments showed that the copolymeric beads were effective in zinc ion removal from aqueous solutions with maximum uptake exceeding 89.0 mg g^–1 using higher grafting efficiency copolymeric beads at pH 5.5. Equilibrium pH studies revealed that zinc biosorption was pH dependent and maximum uptake was obtained at pH 5.5. Dynamics studies showed that the biosorption of zinc was rapid with equilibrium attained within 40 min and the data followed pseudo‐second‐order kinetics. The equilibrium biosorption of zinc ions on the copolymeric beads exhibited a Freundlich isotherm fit. © 2012 Society of Chemical Industry     

Cubic fuzzy Einstein aggregation operators and its application to decision-making

In this paper, we define some Einstein operations on cubic fuzzy set (CFS) and develop three arithmetic averaging operators, which are cubic fuzzy Einstein weighted averaging (CFEWA) operator, cubic fuzzy Einstein ordered weighted averaging (CFEOWA) operator and cubic fuzzy Einstein hybrid weighted averaging (CFEHWA) operator, for aggregating cubic fuzzy data. The CFEHWA operator generalises both the CFEWA and CFEOWA operators. Furthermore, we develop various properties of these operators and derive the relationship between the proposed operators and the exiting aggregation operators. We apply CFEHWA operator to multiple attribute decision-making with cubic fuzzy data. Finally, a numerical example is constructed to demonstrate the established approach.     

Characterization and optimization of mechanical properties of bamboo/nanoclay/polyvinyl alcohol/styrene nanocomposites using response surface methodology

This study demonstrates the effects of impregnation of polyvinyl alcohol (PVA), styrene, and nanoclay on the compositional, mechanical, morphological, and thermal properties of bamboo and its nanocomposites (NCs). Design Expert software was used to optimize the materials and modulus of elasticity as well as the modulus of rupture of the composites. Models were obtained with R2 of 0.9999 and 0.998 for the modulus of elasticity (MOE) and the modulus of rupture (MOR), respectively. The MOE and MOR were found to increase significantly after the formation of NC that indicated improvement of mechanical properties of the bamboo NCs. The polymerization of PVA-co-styrene and dispersion of nanoclay were confirmed by the compositional analysis. The X-ray diffraction analysis showed that the degree of crystallinity was slightly improved upon impregnation with PVA-co-styrene, while reduction in the hydroxyl groups was observed using the Fourier transform infrared. The scanning electron microscopy observation showed tightly filled cell cavities of the bamboo matrix. The thermal stability of the formed NCs were found to be slightly less stable than the raw bamboo (RB) with the differential scanning calorimetry showing low glass transition temperature and the thermogravimetric analysis showed lower decomposition temperatures for the NCs compared to RB as a result of plastic property of the styrene.     

Multiscale analysis of nanoparticles size effects on thermal,elastic, and viscoelastic properties of nano-reinforced polymers

Dependency of microstructural organization, thermal, and mechanical properties of reinforced polymers on the size of the fillers was investigated on model nano-reinforced polymers. Binary systems made of poly(methyl methacrylate) and silica spheres were prepared. While volume fraction was kept constant, silica sphere diameters were varied from 500 nm down to 15 nm. X-ray scattering techniques along with static and dynamic mechanical analysis were conducted on the different prepared binary systems. From our experimental results, it appears that decreasing particle size lead to reduced interchain distances which could be interpreted as matrix densification. In addition, intrachain distance reflecting distance between two carbonyl groups within the same chain was also affected by particle size. Decrease of such distance was interpreted as local segmental rotation induced by size reduction. From mechanical aspects, reducing the size enhanced elastic properties, as evidenced by the increase in the elastic modulus. Dynamic analysis also confirmed such trend where the storage modulus increases for sample with smaller silica particle. Chain mobility quantified through the composite glass transition and the damping factor revealed size-induced mobility restriction through the observed increase of the glass transition. Particle size, when less than 60 nm, appeared as an important parameter contribution to material properties enhancement through multiscale microstructural characterization and mechanical analysis.     

Preparation of gold nanoparticles under presence of the diblock polyampholyte PMAA-<Emphasis Type=Italic>b</Emphasis>-PDMAEMA

The preparation of gold nanoparticles in presence of different weak polyampholytes is investigated. As diblock polyampholytes several poly(methacrylic acid)-block-poly((dimethylamino)ethyl methacrylate), PMAA-b-PDMAEMA, have been used, characterized by different molecular weight and block ratio. HAuCl₄ is used as gold precursor where LiBH₄ is acting as reductive agent to obtain the gold nanoparticles. The addition of gold precursors to aqueous solutions of PMAA-b-PDMAEMA polyampholytes leads to an acidification of the solution resulting in a change of the polyampholyte conformation through protonation of the PDMAEMA blocks. This modification of polyampholyte conformation also allows the tuning of the size and size distribution of the accordingly formed gold nanoparticles. Investigations presented, are performed mainly by AFM of the systems in thin film adsorbed on native oxide-terminated Si substrate. TEM was used to reveal the change in size of the obtained gold nanoparticles.     

A prototype simulation-based optimization approach to model feedstock development for chemical process industry

Incorporating non-traditional feedstocks, e.g., biomass, to chemical process industry (CPI) will require investments in research & development (R&D) and capacity expansions. The impact of these investments on the evolution of biomass to commodity chemicals (BTCC) system should be studied to ensure a cost-effective transition with acceptable risk levels. The BTCC system includes both exogenous, e.g., product demands (decision-independent) and endogenous, e.g., the change in technology cost with investment levels (decision-dependent) uncertainties. This paper presents a prototype simulation-based optimization (SIMOPT) approach to study the BTCC system evolution under exogenous and endogenous uncertainties, and provides a preliminary analysis of the impact of using three different sampling methods, i.e., Monte Carlo, Latin Hypercube, and Halton sequence, to generate the simulation runs on the computational cost of the SIMOPT approach. The results of a simplified case study suggest that annual demand increases is the dominant factor for the total cost of the BTCC system. The results also suggest that using Halton sequence as the sampling method yields the smallest number of samples, i.e., the least computational cost, to achieve a statistically significant solution.