Eco-efficient processes for biodiesel production from waste lipids

The paper proposes innovative eco-efficient processes for converting waste lipid feedstock with up to 35% free fatty acids into biodiesel. Free fatty acids pre-treatment is a key issue, which can be handled by esterification with methanol or glycerol, using hetero- or homogeneous catalyst. The integration with the transesterification stage is possible using methods based on process intensification and heterogeneous catalysis. Three integrated continuous processes are investigated. The first performs the esterification with methanol by reactive absorption and superacid solid catalyst, followed by transesterification by reactive distillation with alkali catalyst. The second method applies the esterification with glycerol at high temperature, coupled with transesterification by heterogeneous catalyst in a variable residence-time plug-flow reactor. The third alternative replaces the second reaction stage with vacuum distillation. In all cases, biodiesel fulfills the specifications of D6751 and EN14214 norms. This result is obtained by kinetic simulation of reactors including free fatty acids esterification and glycerides transesterification. A techno-economic analysis pinpoints the pros and cons of each process. The first process is suited for low free fatty acids content, as used cooking oils. The second and third processes can be applied for higher content of free fatty acids, such as animal fats and greases. Particularly the third process can deliver biodiesel of highest quality, conforming to the cold soak filtration test

Connectivity-, Wiener- and Harary-Type Indices of Dendrimers

Formulas for calculating connectivity-based indices (Randić-type index calculated on vertices, χ, and on edges, ε, Zagreb index, M2, and Bertz index, B ) and distance-based indices (Wiener , W, hyper-Wiener, WW, and Harary-type indices, HWe and HWp) in regular homogeneous dendrimers are derived. Values of the above topological indices for families of dendrimers, with up to 10 orbits, are calculated. Mutual intercorrelation of these indices, in the considered dendrimers, is evaluated

Cyclic distillation technology - A mini-review

Process intensification in distillation systems has received much attention during past decades, with the aim of increasing both energy and separation efficiency. Various techniques, such as internal heat-integrated distillation, membrane distillation, rotating packed bed, dividing-wall columns and reactive distillation were studied and reported in the literature. All these techniques employ the conventional continuous counter-current contact of vapor and liquid phases. Cyclic distillation technology is based on an alternative operating mode using separate phase movement which leads to key practical advantages in both chemical and biochemical processes. This article provides a mini-review of cyclic distillation technology. The topics covered include the working principle, design and control methods, main benefits and limitations as well as current industrial applications. Cyclic distillation can be rather easily implemented in existing columns by simply changing the internals and the operating mode, thus bringing new life to old distillation towers by significantly increasing the column throughput, reducing the energy requirements and offering better separation performance

Separation technology–Making a difference in biorefineries

In the quest for a sustainable bio-based economy, biorefineries play a central role as they involve the sustainable processing of biomass into marketable products and energy. This paper aims to provide a perspective on applications of separations that can make a great difference in biorefineries, by significantly reducing the costs and thus making the processes competitive without subsidies. A parallel is drawn between bio-refinery and petro-refinery, to highlight the specific separation challenges encountered in biorefineries and point out the impact of separations on the total costs. Existing and foreseen separations in biorefineries are reviewed, and the upcoming challenges in the bio-domain (additional to current fossil) are identified. Relevant industrial examples are provided to illustrate the tremendous eco-efficiency benefits of well-designed separation processes based on process intensification principles (e.g. reactive separations, dividing-wall column, affinity and trigger-enhanced separations). These examples also illustrate the low sustainability of several bio-separations currently practiced, in terms of high relative energy requirements, large amounts of gypsum co-production and/or excess use of caustic

Challenges and opportunities for process intensification in Europe from a process systems engineering perspective

Process Intensification (PI) is an effective way to enhance process efficiency and sustainability at affordable costs and efforts, attracting particular interest in the European area, as one of the most important chemical production areas in the world. PI primarily contributes by developing and testing new processing technologies that once integrated within a process improve the overall process performance substantially but as a result, it may alter the overall process (flowsheet) structure and its dynamic behavior. As such PI plays a key role in improving energy efficiency, optimizing resource allocation, and reducing environmental impact of industrial processes, and thereby leading to a cost-effective, eco-efficient, low-carbon and sustainable industry. However, along with opportunities, the PI new technologies have challenges related to failures in longer-term performance. In this respect, Process Systems Engineering (PSE) stance is more on integration aspects of new PI technologies into processes by making process (re)designs, doing operability studies, and performance optimizations within a supply chain setting. PSE contributes to overcoming the challenges by providing systematic approaches for the design and optimization of PI technologies. This perspective paper is a lightly referenced scholarly opinion piece about the status and directions of process intensification field from a PSE viewpoint. Primarily, it focuses on PSE perspectives towards sustainable lower energy usage process systems and provides a brief overview of the current situation in Europe. It also emphasizes the key challenges and opportunities for (new) PI technologies considering their integration in a process in terms of process synthesis and design, process flowsheet optimization, process and plantwide control, (green) electrification, sustainability improvements. Potential research directions on these aspects are given from an industrial and academic perspective of the authors

Reconstructive periodontal therapy with simultaneous ridge augmentation. A clinical and histological case series report

Treatment of intrabony periodontal defects with a combination of a natural bone mineral (NBM) and guided tissue regeneration (GTR) has been shown to promote periodontal regeneration in intrabony defects. In certain clinical situations, the teeth presenting intrabony defects are located at close vicinity of the resorbed alveolar ridge. In these particular cases, it is of clinical interest to simultaneously reconstruct both the intrabony periodontal defect and the resorbed alveolar ridge, thus allowing insertion of endosseous dental implants. The aim of the present study was to present the clinical and histological results obtained with a new surgical technique designed to simultaneously reconstruct the intrabony defect and the adjacently located resorbed alveolar ridge. Eight patients with chronic advanced periodontitis displaying intrabony defects located in the close vicinity of resorbed alveolar ridges were consecutively enrolled in the study. After local anesthesia, mucoperiosteal flaps were raised, the granulation tissue removed, and the roots meticulously scaled and planed. A subepithelial connective tissue graft was harvested from the palate and sutured to the oral flap. The intrabony defect and the adjacent alveolar ridge were filled with a NBM and subsequently covered with a bioresorbable collagen membrane (GTR). At 11–20 months (mean, 13.9 ± 3.9 months) after surgery, implants were placed, core biopsies retrieved, and histologically evaluated. Mean pocket depth reduction measured 3.8 ± 1.7 mm and mean clinical attachment level gain 4.3 ± 2.2 mm, respectively. Reentry revealed in all cases a complete fill of the intrabony component and a mean additional vertical hard tissue gain of 1.8 ± 1.8 mm. The histologic evaluation indicated that most NBM particles were surrounded by bone. Mean new bone and mean graft area measured 17.8 ± 2.8% and 32.1 ± 8.3%, respectively. Within their limits, the present findings indicate that the described surgical approach may be successfully used in certain clinical cases to simultaneously treat intrabony defects and to reconstruct the resorbed alveolar ridge