Search

The prevailing extractive economic model is unsustainable due to the finite nature of resources, thereby necessitating the development of alternative models and policies. The anaerobic digestion (AD) process is key to achieving this objective, as it facilitates the conversion of organic waste into biogas and nutrient-rich digestate. This approach is aligned with the principles of a circular economy and contributes to a reduction in carbon emissions. This study aims to conduct a comprehensive bibliometric analysis of the literature published over the past three decades (1993–2023). The analysis will be based on data drawn from the Scopus database and then analysed using the VOSviewer software, which allows for the interconnection of the revised bibliography through a series of selected keywords. The results demonstrated the existence of four clusters: (i) the beneficial valorisation of waste; (ii) volatile fatty acids and biohydrogen as added value by-products resulting from AD; (iii) lignocellulosic substrates and their by-products; and iv) the main products of AD, biogas and digestate. The bibliometric analysis demonstrates a growing interest in AD within the biorefinery concept in recent years, showcasing its potential for effective waste management and integration into the production chain through the principles of the circular economy.

Abstract To reduce the impact on the environment and enhance the sustainability of resources, it is necessary to promote and strengthen the use of landrace cultivars that advocate regenerative agriculture. In this study, the growth and development as well as the anaerobic digestion (AD) of six different landrace cultivars, two commercial hybrids cultivars and a public genotype of Sorghum bicolor have been evaluated. The landrace cultivars, in general, presented greater heights, biomass yields and compactness shoots as well as similar or an improvement in grain production compare to the commercial varieties. The AD of the different sorghum straws was performed in batch mode at mesophilic temperature (35°C). The landrace cultivar Zahina (ZH) obtained the highest final methane yield (413 ± 79 NL CH4 kg−1 VS, volatile solids) but the landrace cultivars Zahina gigante (ZHG) and Trigomillo (TG) were the ones that obtained the highest methane per biomass production (13.7 and 12.7 NL CH4 shoot unit−1, respectively). By contrast, the commercial varieties were the ones that obtained the lowest methane yields. Two mathematical models, first‐order kinetics and the Transference Function model, were used to fit the experimental data with the aim of describing and simulating the anaerobic biodegradation of these S. bicolor straw varieties and obtaining the kinetic constants. Both models allowed for adequately fitting the experimental results of methane production with time. In particular, the fastest biomethanization occurred using the commercial variety PR88Y20 (PR88) (specific rate constant k = 0.148 ± 0.008 days−1), while the slowest one was obtained from Panizo (PAN) variety (k = 0.064 ± 0.005 days−1). In addition, the highest values of the maximum methane production rate, Rm, were attained for the varieties ZH and PR88, which were 87.1% and 71.3% higher than that achieved for the PAN variety, which exhibited the lowest value.

Thearyl palladium complexes [PdI(C6H4CH2OH-2)(N∧N)] (N∧N = bpy= 2,2′-bipyridyl (1a), tbbpy = 4,4′-di-tert-butyl-2,2′-bipyridine (1b), tmeda= N,N,N′,N′-tetramethylethylenediamine(1c)) were synthesized by oxidative addition of 2-iodobenzylalcohol to one equivalent of “[Pd(dba)2]”(dba = dibenzylideneacetone) in the presence of the N∧N ligands. By reaction of 1awith three equivalentsof XyNC (Xy = 2,6-dimethylphenyl) the insertion complex trans-[PdI{C(NXy)(C6H4CH2OH-2)}(CNXy)2] (2) was formed. The reaction of 1awith KOtBu resulted in the formation of the chelate complex[Pd(κ2-C,O-C6H4CH2O-2)(bpy)] (3), whichcrystallizes as pairs of molecules bridged by hydrogen bonds to waterof crystallization. Complex 3reacts with XyNC, formingthe cyclic imidate N-(2,6-dimethylphenyl)-2-benzofuran-1(3H)-imine (4). By reaction of 3with various primary alkyl halides RCH2X, the complexes[PdX(C6H4CH2OCH2R-2)(bpy)](X = I, R = H (5a), X = Br, R = Ph (5b), p-C6H4CH2Br (5c), p-C6H4Br (5d), and p-C6H4I (5e)) were obtained. When the reaction of 3with p-C6H4(CH2Br)2was carried out in a 2:1 ratio, the dinuclear arylpalladium complex[{(bpy)BrPd(C6H4CH2OCH2-2)}2(C6H4-1,4)] (6) formed. An halide exchange reaction on 5e, using AgOTfand an excess of NaI, afforded [PdI{C6H4(CH2OCH2(C6H4I-4))-2}(bpy)](5f), which by oxidative addition to [Pd(dba)2] in the presence of bpy formed another dinuclear arylpalladium complex,[(bpy)IPd(C6H4CH2-2)O(CH2C6H4-4)PdI(bpy)] (7). Allthe complexes have been extensively characterized by NMR spectroscopy.The crystal structures of 1a, 3·H2O, and 5ewere determined by X-ray diffractionstudies. [ABSTRACT FROM AUTHOR]