plant-wide control of industrial processes using rigorous simulation and heuristics

Ph.DDOCTOR OF PHILOSOPH

Efficient Dehydration and Recovery of Ionic Liquid After Lignocellulosic Processing Using Pervaporation

Background: Biomass pretreatment using certain ionic liquids (ILs) is very efficient, generally producing a substrate that is amenable to saccharification with fermentable sugar yields approaching theoretical limits. Although promising, several challenges must be addressed before an IL pretreatment technology can become commercially viable. One of the most significant challenges is the affordable and scalable recovery and recycle of the IL itself. Pervaporation (PV) is a highly selective and scalable membrane separation process for quantitatively recovering volatile solutes or solvents directly from non-volatile solvents that could prove more versatile for IL dehydration. Results: We evaluated a commercially available PV system for IL dehydration and recycling as part of an integrated IL pretreatment process using 1-ethyl-3-methylimidazolium acetate ([C2C1Im][OAc]) that has been proven to be very effective as a biomass pretreatment solvent. Separation factors as high as 1500 were observed. We demonstrate that \u3e 99.9 wt% [C2C1Im][OAc] can be recovered from aqueous solution (≤ 20 wt% IL) and recycled five times. A preliminary technoeconomic analysis validated the promising role of PV in improving overall biorefinery process economics, especially in the case where other IL recovery technologies might lead to significant losses. Conclusions: These findings establish the foundation for further development of PV as an effective method of recovering and recycling ILs using a commercially viable process technology

Increasing frailty is associated with higher prevalence and reduced recognition of delirium in older hospitalised inpatients: results of a multi-centre study

Purpose Delirium is a neuropsychiatric disorder delineated by an acute change in cognition, attention, and consciousness. It is common, particularly in older adults, but poorly recognised. Frailty is the accumulation of deficits conferring an increased risk of adverse outcomes. We set out to determine how severity of frailty, as measured using the CFS, affected delirium rates, and recognition in hospitalised older people in the United Kingdom. Methods Adults over 65 years were included in an observational multi-centre audit across UK hospitals, two prospective rounds, and one retrospective note review. Clinical Frailty Scale (CFS), delirium status, and 30-day outcomes were recorded. Results The overall prevalence of delirium was 16.3% (483). Patients with delirium were more frail than patients without delirium (median CFS 6 vs 4). The risk of delirium was greater with increasing frailty [OR 2.9 (1.8–4.6) in CFS 4 vs 1–3; OR 12.4 (6.2–24.5) in CFS 8 vs 1–3]. Higher CFS was associated with reduced recognition of delirium (OR of 0.7 (0.3–1.9) in CFS 4 compared to 0.2 (0.1–0.7) in CFS 8). These risks were both independent of age and dementia. Conclusion We have demonstrated an incremental increase in risk of delirium with increasing frailty. This has important clinical implications, suggesting that frailty may provide a more nuanced measure of vulnerability to delirium and poor outcomes. However, the most frail patients are least likely to have their delirium diagnosed and there is a significant lack of research into the underlying pathophysiology of both of these common geriatric syndromes

Life-Cycle Greenhouse Gas and Water Intensity of Cellulosic Biofuel Production Using Cholinium Lysinate Ionic Liquid Pretreatment

Cellulosic biofuels present an opportunity to meet a significant fraction of liquid transportation fuel demand with renewable, low-carbon alternatives. Certain ionic liquids (ILs) have proven effective at facilitating hydrolysis of lignocellulose to produce fermentable sugars with high yields. Although their negligible vapor pressure and low flammability make ILs attractive solvents at the point of use, their life-cycle environmental impacts have not been investigated in the context of cellulosic biorefineries. This study provides the first life-cycle greenhouse gas (GHG) and water use inventory for biofuels produced using IL pretreatment. We explore two corn stover-to-ethanol process configurations: the conventional water-wash (WW) route and the more recently developed integrated high gravity (iHG) route, which eliminates washing steps after pretreatment. Our results are based on the use of a representative IL, cholinium lysinate ([Ch]­[Lys]). We find that the WW process results in unacceptably high GHG emissions. The iHG process has the potential to reduce GHG emissions per megajoule of fuel by ∼45% relative to gasoline if [Ch]­[Lys] is used. Use of a protic IL with comparable performance to [Ch]­[Lys] could achieve GHG reductions up to 70–85%. The water intensities of the WW and iHG processes are both comparable to those of other cellulosic biofuel technologies

Development of an integrated approach for α-pinene recovery and sugar production from loblolly pine using ionic liquids

In the southeastern US, loblolly pine (Pinus taeda L.) is widely used as a feedstock in the wood, pulp and paper industry. In loblolly pine, the oleoresin is composed of terpenes and has long been a valuable source for a variety of chemicals, and has recently attracted interest from a biofuel perspective for the production of advanced cellulosic biofuels. To date, there have been very few examples where a single conversion process has enabled recovery of both terpenes and fermentable sugars in an integrated fashion. We have used the ionic liquid (IL), 1-ethyl-3-methylimidazolium acetate [CCIm][OAc] at 120°C and 160°C in conjunction with analytical protocols using GC-MS, to extract α-pinene and simultaneously pretreat the pine to generate high yields of fermentable sugars after saccharification. Compared to solvent extraction, the IL process enabled higher recovery rates for α-pinene, from three tissues type of loblolly pine, i.e. pine chips from forest residues (FC), stems from young pine (YW) and lighter wood (LW), while also generating high yields of fermentable sugars following saccharification. We propose that this combined terpene extraction/lignocellulose pretreatment approach may provide a compelling model for a biorefinery, reducing costs and increasing commercial viability. Our preliminary techno-economic analysis (TEA) revealed that the α-pinene recovery based on hexane extraction after IL pretreatment could reduce the minimum ethanol selling price (MESP) of ethanol generated from fermentation of sugars recovered from pine by $0.6-1.0 per gal

Simultaneous application of predictive model and least cost formulation can substantially benefit biorefineries outside Corn Belt in United States: a case study in Florida

Previously, a predictive model was developed to identify optimal blends of expensive high-quality and cheaper low-quality feedstocks for a given geographical location that can deliver high sugar yields. In this study, the optimal process conditions were tested for application at commercially-relevant higher biomass loadings. We observed lower sugar yields but 100% conversion to ethanol from a blend that contained only 20% high-quality feedstock. The impact of applying this predictive model simultaneously with least cost formulation model for a biorefinery location outside of the US Corn Belt in Lee County, Florida was investigated. A blend ratio of 0.30 EC, 0.45 SG, and 0.25 CS in Lee County was necessary to produce sugars at high yields and ethanol at a capacity of 50 MMGY. This work demonstrates utility in applying predictive model and LCF to reduce feedstock costs and supply chain risks while optimizing for product yields

Efficient dehydration and recovery of ionic liquid after lignocellulosic processing using pervaporation

Abstract Background Biomass pretreatment using certain ionic liquids (ILs) is very efficient, generally producing a substrate that is amenable to saccharification with fermentable sugar yields approaching theoretical limits. Although promising, several challenges must be addressed before an IL pretreatment technology can become commercially viable. One of the most significant challenges is the affordable and scalable recovery and recycle of the IL itself. Pervaporation (PV) is a highly selective and scalable membrane separation process for quantitatively recovering volatile solutes or solvents directly from non-volatile solvents that could prove more versatile for IL dehydration. Results We evaluated a commercially available PV system for IL dehydration and recycling as part of an integrated IL pretreatment process using 1-ethyl-3-methylimidazolium acetate ([C2C1Im][OAc]) that has been proven to be very effective as a biomass pretreatment solvent. Separation factors as high as 1500 were observed. We demonstrate that >99.9 wt% [C2C1Im][OAc] can be recovered from aqueous solution (≤20 wt% IL) and recycled five times. A preliminary technoeconomic analysis validated the promising role of PV in improving overall biorefinery process economics, especially in the case where other IL recovery technologies might lead to significant losses. Conclusions These findings establish the foundation for further development of PV as an effective method of recovering and recycling ILs using a commercially viable process technology

Switchable ionic liquids based on di-carboxylic acids for one-pot conversion of biomass to an advanced biofuel

Certain ionic liquids have recently been developed as effective solvents for biomass pretreatment, but their adoption has been limited due to availability, production costs, and inhibitory effects on conventional enzymes and microorganisms. We describe here a novel class of ionic liquids based on di-carboxylic acids that have high pretreatment efficiency and are compatible with both commercial enzyme mixtures and microbial fermentation host organisms. This system takes advantage of the two ionization states of di-carboxylic acids to switch from a basic solution that pretreats biomass effectively to an acidic solution with conditions favorable for cellulases and back again for the next round of pretreatment. Lab-scale reactions show 90% conversion of lignocellulosic biomass to fermentable sugars using commercial enzyme mixtures in a one-pot process. We then demonstrate E. coli fermentation of the resulting crude hydrolysate to produce isopentenol without removal of the ionic liquid or inhibitors prior to fermentation. This new process yields high biomass conversion and eliminates several technical and economic problems associated with current ionic liquid-based processes. Our preliminary techno-economic analysis (TEA) suggests biorefineries designed to use these switchable ILs can reduce the minimum selling price (MSP) of their biofuel by more than $1 gal relative to biorefineries utilizing traditional ILs (e.g., [CCIm][OAc]) that have been shown to be very effective at pretreatment but inhibit downstream saccharification and fermentation processes, requiring extensive washing of the pretreated biomass