The policy debate on sustainability: issues and strategy

Prediction of CO 2 storage site integrity with rough set-based machine learning Abstract CO2 capture and storage (CCS) and negative emissions technologies (NETs) are considered to be essential carbon management strategies to safely stabilize climate. CCS entails capture of CO2 from combustion products from industrial plants and subsequent storage of this CO2 in geological formations or reservoirs. Some NETs, such as bioenergy with CCS and direct air capture, also require such CO2 sinks. For these technologies to work, it is essential to identify and use only secure geological reservoirs with minimal risk of leakage over a timescale of multiple centuries. Prediction of storage integrity is thus a difficult but critical task. Natural analogues or naturally occurring deposits of CO2, can provide some information on which geological features (e.g., depth, temperature, and pressure) are predictive of secure or insecure storage. In this work, a rough set-based machine learning (RSML) technique is used to analyze data from more than 70 secure and insecure natural CO2 reservoirs. RSML is then used to generate empirical rule-based predictive models for selection of suitable CO2 storage sites. These models are compared with previously published site selection rules that were based on expert knowledge. Graphic abstract

Catalytic pyrolysis of cellulose with oxides: effects on physical properties and reaction pathways Abstract Fast pyrolysis is a potential technology for converting lignocellulosic biomass into bio-oil, a potential substitute for crude oil and a source of chemicals. Nevertheless, the high amounts of acid, oxygenated compounds, and water content cause the bio-oil to be unsuitable for direct usage. Catalytic fast pyrolysis (CFP) is able to improve bio-oil properties so that downstream upgrading processes may be economically feasible. The catalytic effects of calcium oxide (CaO), magnesium oxide (MgO), and zinc oxide (ZnO) on the pyrolysis of lignocellulosic biomass were investigated and were found to be attractive. However, the reaction pathways involved have not been comprehensively compiled to our knowledge. This study aimed to study the change in physical properties of bio-oils at the simplest form upon the addition of the oxides and to provide an understanding on the catalytic reaction pathways. Such study is beneficial to further explore the potential of selected oxides in enhancing the properties of bio-oil from biomass with different lignocellulosic compositions. Experiments were carried out in a fixed-bed reactor at laboratory scale to mimic large-scale processes in a controlled environment. The catalysts exhibited strengths at different bases. CaO catalyst showed the most favorable physical effects in terms of reducing the acidity of cellulose-derived bio-oils without increasing the water content significantly and without compromising with the yield. As for deoxygenation ability, ZnO catalyst exhibited better performance. Graphic abstract

Environmental and economic prospects of biomaterials in the automotive industry Abstract This study provides an overview of the application of biomaterials in automotive industries and their economic and environmental implications. It also discusses the recent developments, ongoing activities, and the major constraints that need to be addressed for commercial application. Innovative material selection and processing methods improve the environmental performance of biocomposite materials as well as their properties. Numerous efforts have been made in evaluating the environmental impacts of biomaterials; however, impacts of land use change have been left out, and the economic analysis has been conducted to a limited extent. A broader sustainability analysis is essential for its commercial applications and for any investment in biocomposite industries to alleviate environmental, economic, and safety risks. The proliferation of life cycle sustainability assessment and common material data system in the biocomposite industry may accelerate the acceptance of biocomposite, thus improving the potential social and environmental benefits. Graphic abstract

Protocol encompassing ultrasound/Fe 3 O 4 nanoparticles/persulfate for the removal of tetracycline antibiotics from aqueous environments Abstract The presence of residual antibiotics in the environment is one of the major global concerns, and it is imperative to control their discharge in water bodies. The present study used a combination of Fe3O4 nanoparticles/persulfate in conjunction with ultrasound to address this problem; the influence of effective parameters in the remediation process, persulfate concentration, nanoparticle concentrations, initial antibiotic concentration, contact time and pH was investigated. The highest removal rate of tetracycline antibiotic was observed at pH 10, the amount of magnetic nanoparticles being (0.3 g/L), with persulfate concentration at 4 mM for the removal of antibiotic concentration at 10 mg/L; TC and COD removal efficiency is 92.99 and 79.85%, respectively. The deployment of sonocatalytic process, along with the use of magnetite nanoparticles and persulfates as oxidizing agents, appears to be an effective means for decreasing the high-level tetracycline concentration in water. Graphic abstract

Forward osmosis desalination using pectin-coated magnetic nanoparticles as a draw solution Abstract In this study, magnetic Fe3O4 nanoparticles and pectin-coated magnetic Fe3O4 nanoparticles were used as a potential draw solution in forward osmosis (FO) water desalination applications due to enhanced water flux and easy recovery of the nanoparticles using magnetic separation. The effect of the pectin coating and the operating conditions on the FO performance were studied. The results showed that the fabricated nanoparticles have spherical and rod-like shapes of magnetite Fe3O4 crystal phase and superparamagnetic properties, which allow for facile recovery of the magnetic nanoparticles using a simple magnet. Water flux of 35.7 LMH was obtained using uncoated magnetic Fe3O4 nanoparticles as draw solution against deionized water as the feed solution. The effect of increasing water salinities in the feed side was studied, and water flux decrease of 14%, 58%, and 76% was observed for 0.25, 0.50, and 1.00 g% NaCl solution, respectively. Furthermore, the effect of the pectin coating (0.5 and 1.0 g%) on the use of magnetic nanoparticles as draw solution proved to have a significant effect on the pure water flux. The water flux of 2.6 LMH was obtained against 5.5 g%, 55,000 ppm, NaCl solution as the feed solution showing the potential use of magnetic nanoparticles as draw solution for brine management. The salt rejection exceeded 95% for all experiments. Therefore, this study demonstrates the superiority of magnetic nanoparticles as draw solution and provides new insights in using FO directly for desalination applications. Full economic analysis of the use of magnetic nanoparticles as draw solution for FO processes is still needed and is recommended for future research. Graphic abstract

Characterization of different sugarcane bagasse ashes generated for preparation and application as green products in civil construction Abstract The characterization and manipulation of solid residues according to their types can enable different ways of efficient and specialized applications in the development of products. In particular, the sugarcane bagasse ash, a solid agro-industrial residue resulting from the burning of the bagasse in boilers for energy cogeneration, attracts attention due to its high availability. This study aims to systematically characterize the bottom, fly and mixed ashes, submitted to low-cost processings, in order to do a better directioning of their applicabilities in civil construction products. The processings of the ashes consist basically in stages of sieving and reburning at 600 °C. The results showed that the chemical and physical properties of the bottom and mixed ashes are similar between them and are especially recommended for applications in replacement of fine aggregates in civil construction products. The fly ash sample, without reburning and with amorphous structural organization, satisfies prerequisites for evaluations of pozzolanic applications in partial replacement of cementitious materials. Graphic abstract

Greener assembling of MoO 3 nanoparticles supported on gum arabic: cytotoxic effects and catalytic efficacy towards reduction of p -nitrophenol Abstract An economical and easy one-step method for the biosynthesis of highly stable molybdenum trioxide (MoO3) nanoparticles was developed using gum arabic as a bio-template; ensuing nanoparticles (NP) were characterized by X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, Raman spectroscopy, UV–visible spectroscopy, transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDX). The crystallinity and purity of MoO3 nanoparticles in the orthorhombic phase were confirmed by XRD analysis, and their rod-shaped identity (average sizes ranging from 7.5 to 42 nm) were observed by TEM. Cytotoxic effects of the NP were monitored using Hep G2 (human liver cancer) and HEK 293 (human embryonic kidney) cell lines via 2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide assays. The results of this study revealed that MoO3 nanoparticles are nontoxic towards Hep G2 cell lines and displayed negligible toxicity, even at very high concentrations (1000 ppm), although had moderate toxicity towards HEK 293 cells. Furthermore, their catalytic activity was evaluated for the reduction of p-nitrophenol to p-aminophenol. Graphical abstract Synopsis: Green synthesis of MoO3 nanorods using gum arabic demonstrated as an eco-friendly catalyst for the conversion of p-nitrophenol with negligible toxicity towards Hep G2 cell lines.

Waste heat recovery through organic flash cycle (OFC) using R245fa–R600 mixture as the working fluid Abstract R245fa and R600 are two working fluids with which organic flash cycle (OFC) yields acceptable thermodynamic and economic performance to recover waste heat from low-temperature flue gas free from SO2. However, very high flammability of R600 and higher global warming potential (GWP) of R245fa are two issues of serious concern. Mixture with suitable mole fraction of these two fluids as the optimum working fluid for OFC is explored in this study. A mixture of R245fa and R600 with a mole fraction ratio (0.6/0.4) is selected conservatively as the working fluid of the OFC to suppress the flammability of R600. The corresponding value of GWP of the mixture comes below 800 kg of CO2 per kg of working fluid. It is observed that OFC using this mixture may yield higher work output per kg of flue gas flow and lower bare module cost/kW compared to that of OFC using either of the pure working fluid. OFC yields the highest work output per kg of flue gas for an R245fa/R600 mixture with (0.4/0.6) mole fraction ratio. Bare module cost per unit power output becomes a minimum when R245fa mole fraction is 0.37 in the mixture.

Greenhouse gas mitigation potential under different rice-crop rotation systems: from site experiment to model evaluation Abstract Crop rotation systems in fields could improve crop production and indirectly affect carbon and nitrogen dynamics due to multiple fertilizer applications. Therefore, it is important to evaluate the impact of these crop rotation systems on greenhouse gas (GHG) emissions. Field experiments were conducted with three different rotation systems, and the DeNitrification–DeComposition (DNDC) model was applied to monitor and estimate crop yields and GHG emissions during three rice-upland crop rotational periods (from June 2013 to May 2016). Low methane (CH4) and nitrous oxide (N2O) emissions were observed in rice-Chinese milk vetch and single rice rotation systems. The simulated crop yields fit the observed data very well (d > 0.80, EF > 0.70) after the model was calibrated by adjusting the crop parameters. The model-simulated daily and annual CH4 emissions agreed well with the field measurements (d > 0.7, EF = 0.41–0.98). The simulated N2O (d = 0.01–0.70, EF < 0 or close to 0) of accumulated emissions and daily fluxes (d = 0.07–0.14, EF < 0) showed low levels of accuracy with field observations. The GHG emissions in Shanghai rice paddy were different under various rotation systems, with the following order: single rice rotation system < rice-Chinese milk vetch rotation system < baseline rotation system of Shanghai paddy < 1/3 (rice-Chinese milk vetch + single rice + rice-winter wheat rice-winter) rotation system < rice-winter wheat rotation system under the same nitrogen loading. The DNDC was able to predict rice yields and GHG emissions under different crop rotation systems. The results provide positive reliable indications that crop rotation systems have the potential to reduce GHG emissions; e.g., the rice-Chinese milk vetch rotation system could mitigate the CH4 and N2O emissions. Graphic abstract