A tandem simulated moving bed (SMB) process for insulin purification has been proposed and validated experimentally. The mixture to be separated consists of insulin, high molecular weight proteins, and zinc chloride. A systematic approach based on the standing wave design, rate model simulations, and experiments was used to develop this multicomponent separation process. The standing wave design was applied to specify the SMB operating conditions of a lab-scale unit with 10 columns. The design was validated with rate model simulations prior to experiments. The experimental results show 99.9% purity and 99% yield, which closely agree with the model predictions and the standing wave design targets. The agreement proves that the standing wave design can ensure high purity and high yield for the tandem SMB process. Compared to a conventional batch SEC process, the tandem SMB has 10% higher yield, 400% higher throughput, and 72% lower eluant consumption. In contrast, a design that ignores the effects of mass transfer and nonideal flow cannot meet the purity requirement and gives less than 96% yield.

The sorbent-solvent interactions for amylose tris(3, 5-dimethylphenylcarbamate) (ADMPC) with five commonly used solvents, hexane, methanol, ethanol, 2-propanol (IPA), and acetonitrile (ACN), are studied using attenuated total reflection infrared spectroscopy (ATR-IR) of thin sorbent films, X-ray diffraction (XRD) of thin films, (13)C cross polarization/magic angle spinning (CP/MAS) and MAS solid state NMR of polymer-coated silica beads (commercially termed "Chiralpak AD"), and DFT modeling. The ADMPC-polymer-coated silica beads are used commercially for analytical and preparative scale separations of chiral enantiomers. The polymer forms helical rods with intra- and inter-rod hydrogen bonds (H-bonds). There are various nm-sized cavities formed between the polymer side-chains and rods. The changes in the H-bonding states of the C=O and NH groups of the polymer upon absorption of each of the five solvents at 25 degrees C are determined with ATR-IR. The IR wavenumbers, the H-bonding interaction energies, and the H-bonding distances of the polymer side-chains with each of the solvent molecules are predicted using the DFT/B3LYP/6-311+g(d,p) level of theory. The changes in the polymer crystallinity upon absorption of each solvent are characterized with XRD. The changes in the polymer crystallinity and the H-bonding states of C=O groups are also probed with (13)C CP/MAS solid-state NMR. The changes in the polymer side-chain mobility are detected using (13)C MAS solid-state NMR. The H-bonding states of the polymer change upon absorption of each polar solvent and usually result in an increase in the polymer crystallinity and the side-chain mobility. The polymer rods are reorganized upon solvent absorption, and the distance between the rods increases with the increase in the solvent molecular size. These results have implications for understanding the role of the solvent in modifying the structure and behavior of the polymer sorbents.

The effects of the backbone and side chain on the molecular environments in the chiral cavities of three commercially important polysaccharide-based chiral sorbents--cellulose tris(3,5-dimethylphenylcarbamate) (CDMPC), amylose tris(3,5-dimethylphenylcarbamate) (ADMPC), and amylose tris[(S)-alpha-methylbenzylcarbamate] (ASMBC)--are studied by attenuated total reflection infrared spectroscopy (ATR-IR), X-ray diffraction (XRD), 13C cross-polarization/magic-angle spinning (CP/MAS) and MAS solid-state NMR, and density functional theory (DFT) modeling. These sorbents are used widely in preparative-scale chiral separations. ATR-IR is used to determine how the H-bonding states of the C=O and NH groups of the polymer depend on the backbone and side chain. The changes in the polymer crystallinity are characterized with XRD. The changes in the polymer helicity and molecular mobility for polymer-coated silica beads (commercially called Chiralcel OD, Chirapak AD, and Chiralpak AS) are probed with 13C CP/MAS and MAS solid-state NMR. The IR wavenumbers and the NMR chemical shifts for the polymer backbone monomers and dimers and the side chains are predicted at the DFT/B3LYP/6-311+g(d,p) level of theory. It is concluded that the molecular environments of the C=O, NH, and phenyl groups show significant differences in intramolecular and intermolecular interactions and in the nanostructures of the chiral cavities of these biopolymers. These results have implications for understanding how the molecular environments of chiral cavities of these polymers affect their molecular recognition mechanisms.

About five billion tons of plastic waste have accumulated in landfills and the natural environment over the past 50 years. Polypropylene (PP) waste accounts for about 23% of the total plastic waste. Converting PP waste into useful products can reduce the accumulated waste and associated risks to the environment and human health. In this study, model PP was converted into oil using supercritical water at 380–500 °C and 23 MPa over a reaction time of 0.5–6 h. Up to 91 wt % of model PP was converted into oil at 425 °C with a 2–4 h reaction time or at 450 °C with a 0.5–1 h reaction time. Higher reaction temperatures (>450 °C) or longer reaction times (>4 h) led to more gas products. The oil products consisted of olefins, paraffins, cyclics, and aromatics. About 80–90 wt % of the oil components had the same boiling point range as naphtha (25–200 °C) and heating values of 48–49 MJ/kg. Reaction pathways for converting model PP into oil under the tested conditions were proposed. Preliminary analyses indicate that this conversion process is net-energy positive and potentially has a higher energy efficiency and lower greenhouse gas emissions than incineration and mechanical recycling. The oil derived from PP has the potential to be used as gasoline blendstocks or feedstocks for other chemicals.

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