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Waste disposal management and the energy crisis are important challenges facing most countries. The fruit-processing industry generates daily several tons of wastes, of which the major share comes from banana farms. Anaerobic digestion (AD) technology has been applied to the treatment of wastewater, animal slurry, food waste, and agricultural residues, with the primary goals of energy production and waste elimination. This study examines the effect of organic loading (OL) and cow manure (CM) addition on AD performance when treating banana peel waste (BPW). The maximum daily biogas production rates of banana peels (BPs) with a CM content of 10%, 20%, and 30% at 18 and 22 g of volatile solids (gvs) per liter were 50.20, 48.66, and 62.78 mL·(gvs·d)−1 and 40.49, 29.57, and 46.54 mL·(gvs·d)−1, respectively. However, the daily biogas yield showed no clear interdependence with OL or CM content. In addition, a kinetic analysis using first-order and cone models showed that the kinetic parameters can be influenced by the process parameters. Keywords: Biogas, Banana peels, Cow manure, Anaerobic treatment, Batch test, Kinetic study

This paper presents a detailed case study on the effective upcycling of a post-industrial plastic waste stream to a renewed compound, fit for re-use in a new application. The material investigated was a PET-contaminated recycled PP, destined for a high-impact, medium-stiffness application. After two research trials and one large-scale industrial trial, an upcycling formulation was determined to bring the recyclate to the required level of the new application, thus closing this specific material loop within the case company. The used methodology adheres to the Design from Recycling principle, in which industrially available (mechanically) recycled polymer materials are matched to potential new products. The design strategy starts from either the properties of an available recycled polymer (and then defines the product) or from the functional boundary conditions of the product (and then selects the material and/or an optional material upcycling step). The Design from Recycling principles can elegantly be combined with those of Design for Recycling, within the framework of a Circular Economy.

The design and application of an electrochemical micro-flow reactor for the aldol reaction of acetone to diacetone alcohol (DAA) is reported. The modular reactor could be readily disassembled and reassembled to change the electrodes, incorporate a membrane and remove possible obstructions. The productivity and efficiency was quantified. Using a platinum deposit as electrocatalyst or an inert glassy carbon electrode as working electrode, the maximum obtainable equilibrium concentration of ±15 m% was reached after a single pass up to a flow rate of 8 ml min−1, yielding 0.57 g min−1 DAA (3.46 mmol cm−3 min−1) at an efficiency of 0.33 g C−1 on platinum and 0.50 g min−1 (3.04 mmol cm−3 min−1) at 1.20 g C−1 on glassy carbon. Note that no optimisation studies have been made in the present paper.

In this paper a structure-activity and structure-selectivity relation is established for three commercial TiO 2 sources (P25, P90, and PC500). Morphological and electronic parameters of the photocatalysts are determined using widely applicable and inexpensive characterization procedures. More specifically, the electronic properties are rigorously characterized using an electron titration method yielding quantitative information on the amount of defect sites present in the catalyst. Surface photovoltage measurements on the other hand provide complementary information on the charge carrier recombination process. As model reaction, the degradation of a solid layer of stearic acid is studied using an in situ FTIR reaction cell that enables to investigate the catalyst surface and possible formation of reaction intermediates while the reactions are ongoing. We show that the order of photocatalytic conversion is PC500 > P90 > P25, matching the order of favorable morphological properties. In terms of selectivity to CO 2 formation (complete mineralization), however, this trend is reversed: P25 > P90 > PC500, now matching the order of advantageous electronic properties, i.e. low charge carrier recombination and high charge carrier generation. With this we intend to provide new mechanistic insights using a wide variety of physical, (wet) chemical and operando analysis methods that aid the development of performant (self-cleaning) photocatalytic materials.

This paper deals with a study of voids in amorphous glassy polymers that exhibit elastic-viscoplasticity with rate dependent yield, intrinsic softening and progressive strain hardening at large strains. The study is motivated by the plastic deformation in voided polymer-rubber blends caused by cavitation of the rubber particles, and thus attempts to contribute to the understanding of the toughening mechanisms in blends. Axisymmetric cell analyses are presented to study the plastic deformation around initially spherical voids and their resulting growth in terms of size and shape up to large overall strains. This void growth is demonstrated to inherit particular properties from the typical features of plasticity in glassy polymers, viz. small strain softening and large strain hardening. The role of strain localization into shear bands and their subsequent propagation in controlling void growth is highlighted. Furthermore, an approximate constitutive model is presented for the description of the macroscopic overall behaviour of porous glassy polymers. This model includes a modification of existing porous plasticity models to account for elasticity effects on the initiation of overall plasticity, which are important in polymers because of their relatively high yield strain. Its predictions are compared with the results from the numerical cell analyses.

This issue of Advances is devoted to the memory of Hans-Joachim Schulze who, before his untimely death, made substantial contributions in the domains of flotation, wetting and particle interaction, often under adverse working conditions. Many of his publications involve hetero-interaction between different oxides or between solids and air bubbles. In the present paper, the theory for the electric interaction between charged interfaces is reviewed and extended by considering regulation on the Gouy-Stern level, including hetero-interaction. We start from a generalization of the phenomenon of regulation, distinguishing electrostatic, chemical and entropic contributions to the regulation capacity. The analysis is carried out in the mean field approximation for flat double layers. Against this background we review and discuss the existing literature. It is shown that for an appropriate account it is mandatory to include Stern layers, to which not only electrical but also chemical and entropic contributions to the regulation capacity can be attributed. It is demonstrated that interaction at constant diffuse double layer potential or -charge works only at rather large distance of separation. At shorter distance, substantial deviations from this behaviour are found, with a trend that interaction at (about) constant potential is the better obeyed the higher the corresponding regulation capacities are. A lattice model is elaborated to visualize the profiles of the (surface, Stern and diffuse) charges and the corresponding potential changes upon overlap, including the cases where strong induction leads to charge-inversion of the layer with the larger regulation capacity. A number of elaborations is presented, but the potentialities of the model are virtually unlimited.