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There is currently an interest in optimizing the structural design to improve materials' strength to weight ratio or improve stiffness for energy absorption. As such, cellular structures are continuously studied and improved. However, it is a well-known fact in the literature that one primary mechanism of failure of a honeycomb is the formation of shear bands. The impacts of these shear bands bring many questions and unknowns, especially when the cellular structures are created with the increasingly popular manufacturing technique of 3D printing. Therefore, understanding the deformations in 3D printed honeycomb structures is necessary to explain the behavior of materials generated through new additive manufacturing techniques and further the knowledge of the deformation localization and, consequently, formations of shear bands in the deformation process of cellular structures.In the first phase of this work, samples with a unit cell regular hexagonal honeycomb format were designed and manufactured using masked-stereolithography (M-SLA). After the curing process, the samples were prepared with a paint application in the format of speckle, and DIC was realized in a compression experiment to identify and analyze the presence of high strain regions indicating the presence of shear bands. A second phase was then conducted, aiming to consider the control and manipulation of the shear band through the utilization of relief holes. The results demonstrated that adding incisions in specific parts of the polymeric honeycomb makes it possible to change its strain spread through the shear band and change its toughness.

The emerging contaminants (ECs) such as estrogen hormones, perfluorinated compounds (PFCs), bisphenol A (BPA) and 1, 4-dioxane have been detected in natural water bodies at a noticeable level worldwide. The presence of ECs in the aquatic environment can pose potential threats to aquatic organisms as well as human world. Ion-exchange is a highly efficient technology for the removal of heavy metal ions and natural organic materials (NOMs) due to the nature of exchanging similar charged ions. However, this technology has not been explored for removing ECs. In this study, four categories of ECs: estrogen hormones (12), perfluorinated compounds (10), bisphenol A and 1, 4-dioxane were used as model contaminants. The adsorption of each category of ECs onto various types of polymeric resins (MN100, MN200, A530E, A532E and C115) was investigated. The removal of ECs was tested under batch and column mode. The effects of pH, resin dosage, and contact time on the removal of ECs were studied in batch mode; isotherm and kinetics models were applied to fit the experimental data. Column experiments were conducted to verify the practicability of the polymeric resins. Adsorption results have shown that both MN100 and MN200 resins could efficiently remove estrogen hormones mixture (more than 95%), and bisphenol A (more than 80%) with the initial concentration of 100 ìg/L; A532E and A530E could remove perfuorinated compounds mixture (more than 99%) with the initial concentration of 100 ìg/L. As pH increased from 9 to 11, the adsorption capacity onto polymeric resins decreased dramatically for estrogen hormones such as 17á-ethinylestradiol, estriol, 17â-estradiol, 17á-estradiol, estrone, 17á-dihydroequilin and equilin as well as bisphenol A. The adsorption of estrogen hormones and bisphenol A onto MN100 and MN200 resins reached the equilibrium within 24 hours, whereas the adsorption of perfluorinated compounds onto A532E and A530E reached the equilibrium within 8 hours. It was also observed that the adsorption of PFCs largely depends on the C-C chain length. PFCs with longer chain yielded lower adsorption efficiency onto the ion-exchange resins A532E and A530E. Adding salinity decreased the first-order rate constants for the adsorption of bisphenol A onto MN100 and MN200 resins. Fixed-bed column experiment results with estrogen hormones mixtures confirmed that the polymeric resins were good candidates in the removal of estrogen hormones. Trimegestone was the first compound detected in the effluent in the column test while 17â-estradiol, 17á-estradiol were the last. 80% of the exhausted resins (MN100 and MN200) by bisphenol A were regenerated by using pure methanol as regeneration solution. Polymeric resins were not effectively removing 1, 4-dioxane from the aqueous solution. / Civil Engineering

A large number of organic contaminants are commonly found in industrial and municipal wastewaters. Aromatic compounds, such as phenol, aniline and their derivatives, are contaminants of high priority and usually coexist in waste streams from industries of, for example, aromatic amine compounds and ammonolysis of phenols. Thus, for proper unit design to remove contaminant mixtures by adsorption, multi-component adsorption models are necessary. The present work was aimed at examining the applicability of Ideal Adsorbed Solution Theory (IAST), a prevailing thermodynamic model, and its derivative i.e. Segregated IAST (SIAST) and Real Adsorbed Solution Theory (RAST) to multi-solute adsorption from the aqueous phase, specifically, bi-solute adsorption of phenols, anilines and nitrobenzene onto a hyper-crosslinked polystyrene resin, MN200. Based on the experimental bi-solute adsorption isotherms, we have successfully developed methods for modeling with RAST incorporated with Wilson equation, Nonrandom two-liquid (NRTL) model, and an empirical four-parameter equation developed in this work. It turns out that our proposed four-parameter equation can fit the activity coefficients, γ_(i ), better than the other two equations and thus enhanced the accuracy of RAST in predicting bi-solute adsorption equilibrium. Besides successfully developing methods for properly designing binary-solute batch experiments and accurately modeling with RAST, two empirical linear relationships have been developed for the adsorption of a number of infinite dilute solutes in the presence of a major contaminant (either 4-methylphenol or nitrobenzene). Results show that polyparameter linear free energy relationships have a great potential in predicting adsorbed phase activity coefficients of solutes when the adsorbed amounts are dominated by the major contaminant and the adsorbed mixture resembles infinite dilute solution. Activity coefficients under such conditions were represented by〖 γ〗_i^∞ and were successfully extrapolated to γ_(i )at non-infinite conditions by γ_(i )models i.e. Wilson equation. To the best of our knowledge, this is the first systematic study predicting adsorbed phase activity coefficients for bi-solute adsorption. In addition, our tri- and tetra-solute adsorption data showed that the predominating solute, NB in this case, solely contributed to the competitive effect while the dilute solutes tend not to interact with each other. This indicates that for each solute, the competitive effects can be independently considered and a multi-component system with n components but only one component dominating can be treated as (n-1) bi-solute systems separately. This will significantly simplify the calculation for modeling multi-component adsorption while it is also close to many real systems where there is one major contaminant or a large amount of NOM in present. Our findings have proved a major step forward to accurately modeling multi-solute adsorption for proper unit design of adsorption processes. / Civil Engineering