Low-CO2 Binders for restoring a Pb-contaminated Soil: Improvements and Drawbacks with respect to Ordinary Portland Cement

The remediation of heavy metal contaminated soils is usually approached with binder-based techniques, like solidification/stabilization (S/S), and ordinary Portland cement (OPC) as the main binding agent. This paper reports our preliminary attempts of substituting traditional OPC with more environmentally sustainable alkali-activated cements, in the S/S of a Pb-contaminated soil. The treatment of Pb contamination is complicated by the amphoteric behavior of Pb, whose mobility is increased at high pH values, which are characteristic of cementitious systems. The use of alkali-activated cements proved to be suitable for soil remediation, with different performances depending on the formulation studied. These preliminary findings may be further enhanced by long-term investigations and further optimization of the alkaline activating solution, as first steps towards the improvement of the environmental impact of soil remediation technologies

Trends and characteristics of employing cavitation technology for water and wastewater treatment with a focus on hydrodynamic and ultrasonic cavitation over the past two decades: A Scientometric analysis

Cavitation-based technologies have emerged as a sustainable and effective way to treat natural waters and wastewater, considering their increasing scarcity due to pollution and climate change. For this reason, this work aimed to conduct a scientometric analysis on the topic of cavitation for water and wastewater treatment during the last 20 years, from 2001 to August 2022. We focused on hydrodynamic and ultrasonic cavitation as the prevalent methods of inducing cavitation. Furthermore, an in-depth study on the main trends regarding the number of publications and citations, keywords co-occurrence and evolution, and countries' publication trends was carried out to investigate the future direction of this research topic. The data was gathered from the Web of Science database and analyzed by the Visualization Of Similarities software. This work focused on: i) publication and citation trends, ii) scientific categories, iii) countries' contribution to the topic of cavitation, iv) prominent journals, v) keyword co-occurrence and cluster analysis, and vi) keyword evolution analysis. Results showed a significant increase in publications during the past 5 years. The scientific categories with the highest number of publications were “environmental sciences” and “environmental engineering,” with a combined share of 19.4 % of publications. Keywords evolution analysis showed that limited focus was given to topics related to “energy” and “energy efficiency” in the field of cavitation, but with the rising importance of each process's sustainability, the attention given to these concepts will increase in the future. Future directions for the topic of cavitation-related water and wastewater treatments will shift towards more environmentally friendly applications of hydrodynamic and ultrasonic cavitation as well as towards more green and sustainable approaches to address the increasing water pollution problems and shortage. Moreover, it will include other uses besides water treatment such as manufacturing nanomaterials, food production, and medicine

The coupling of carbon dioxide with ethene to produce acrylic acid sodium salt in one pot by using Ni(II) and Pd(II)-phosphine complexes as precatalysts

The use of CO2 as a feedstock for chemical synthesis is considered as a viable alternative option to some traditional processes. One of the most interesting challenge for the industry is represented by the CO2 coupling with olefins to produce acrylate. Only recently, with the choice of suitable ligands and the use of a sacrificial base, a selective catalytic reaction was established by using Ni(0)-based complexes. The one-pot reaction, which leads to the highest TON (107 mol/mol Ni, in 20 h) reported so far, was successfully developed starting from Ni(0)-based precursors in the presence of disphosphine ligands, a large excess of base and of finely powdered zinc. In the present paper, we carried out the catalytic synthesis of sodium acrylate from CO2 and ethene, in one-pot, by using Ni(II)-chloride and Pd(II)-chloride phosphine-complexes as precatalyst. The reaction occurs under basic conditions and without adding any external reductants. The Ni(II) complexes lead to higher TON than the respective Pd(II) precursors and the best results are obtained by using diphosphines having high bite angles. Such catalysis is favored by aprotic and polar solvents in which a TON of 290 mol/mol Ni is reached by using the [NiCl2 (dppp)] precursor in DMSO. Furthermore the TON could be increased by increasing the temperature, the base concentration and by using diphosphine ligands having high bite angle

New magnetically recoverable palladium-based catalysts active in the alkoxycarbonylation of iodobenzene

New magnetically recoverable catalysts have been synthesized by deposition of 1% palladium (Pd)-metal on the polymer poly(1-oxo-trimethylene), containing 15% of magnetite. The magnetite allows the complete recovery of the catalyst with the simple application of an external magnetic field. The activity of such a catalyst has been studied under phosphine-free conditions in the alkoxycarbonylation of iodobenzene to the corresponding benzoic acid esters.New magnetically recoverable catalysts have been synthesized by deposition of 1 % palladium (Pd)-metal on the polymer poly(1-oxo-trimethylene), containing 15 % of magnetite. The magnetite allows the complete recovery of the catalyst with the simple application of an external magnetic field. The activity of such a catalyst has been studied under phosphine-free conditions in the alkoxycarbonylation of iodobenzene to the corresponding benzoic acid esters

Catalitic chemical fixation of CO2 through syntehsis of acrylic monomers

The effects of CO2 emissions on global climate are well known and studied problems. Many ways of limiting such emissions have been suggested, from the injection in exhausted oil fields, to the chemical fixation of carbon dioxide in more stable forms. Among the several routes proposed, the use of carbon dioxide as a raw material in the green synthesis of strategic chemicals has gained a great interest. From an industrial point of view, an interesting target is represented by the synthesis of acrylate using CO2 and ethene. Several transition-metals have been showed catalytic activity in such reaction in particular under controlled basic conditions. As in the literature it is reported that the reaction of CO2 with ethene to acrylates is catalyzed by Ni(0)-phosphine complexes, in the present work we have been studied the catalytic activity of a series of Ni(II) and Pd(II) diphosphine-complexes

New magnetically recoverable heterogeneous Pd-catalyst active in the alcoxycarbonylation of iodobenzene

Carbon-carbon bond formation is a long-standing challenge to organic chemists and several catalytic approaches have been developed during the past decades. Among these, the palladium-catalyzed carbonylation of aryl halides and their derivatives represents a powerful method for the synthesis of many aromatic compounds; especially, carboxylic acids and their derivatives. However, the difficult separation of the products from catalyst in the traditional homogeneous catalysis hinders sometimes its application in industrial process. This problem can be overcome by means of heterogeneous catalysis used nowadays in many industries to produce a variety of commercial products. Although in the heterogeneous catalysts the catalyst can be readily recovered usually by filtration or centrifugation catalyst recovery and reuse remain the two most important features for many green synthetic methods.Recently, new smart supports (magnetic nanoparticles, MNPs) have emerged and have great potential for catalyst recovery, because magnetic separation from the reaction mixture with an external permanent magnet is typically simpler and more effective than filtration or centrifugation as it prevents loss of the catalyst

Emissions of pharmaceuticals and plant protection products to the lagoon of Venice: development of a new emission inventory

Estimating the emissions of chemical pollutants to water is a fundamental step for the development and application of effective and sustainable management strategies of water resources, but methods applied so far to build chemicals inventories at the European or national scale show several limitations when applied at the local scale. The issue is particularly relevant when considering contaminants of emerging concern (CECs), whose environmental releases and occurrence are still poorly studied and understood. In this work, an approach to estimate water emissions of nine active pharmaceutical ingredients (APIs) and ten most applied plant protection products (PPPs) is presented, considering proxy indicators (e.g., sales data and census information). The application area is the lagoon of Venice (Italy), a complex transitional environment highly influenced by anthropic pressures (e.g., agricultural and industrial activities, animal breeding, and wastewater discharge). The presented approach can be tailored to the information available for any local scale case study. Data on annual regional sales of PPPs and APIs were integrated with georeferenced demographic and economic statistics (such as census and land-use information) to estimate chemicals emissions to surface water and groundwater. A sensitivity and uncertainty analysis identified the main factors affecting emissions estimates, and those contributing more significantly to results uncertainty. Results showed the highest estimated emissions of APIs for antibiotics (i.e., amoxicillin, clarithromycin, azithromycin, and ciprofloxacin) used for humans and animals, while most of hormones’ emission (i.e., 17- α-ethinylestradiol and 17-β-estradiol) derived from animal breeding. Regarding PPPs, glyphosate and imidacloprid emissions were one to two orders of magnitude higher compared to the other chemicals. Uncertainty and sensitivity analysis showed that the variability of each parameter used to estimate emissions depends greatly both on the target chemical and the specific emission source considered. Excretion rates and removal during wastewater treatment were major key parameters for all the target pharmaceutical compounds, while for PPPs the key parameter was their loss into the natural waters after application

The validation of converting pyrite ash‐contaminated soil into End‐of‐Waste by the High‐Performance Solidification/Stabilization process application

One of the major challenges to establishing more sustainable management strategies than landfill disposal of metals-contaminated soils is the lack of End-of-Waste (EoW) criteria defined at the European and national levels. Another limitation stems from the scarcity of information on industrial-scale applications of treatment technologies able to obtain safe and reusable materials from such contaminated waste. In this context, the High-Performance Solidification/Stabilization process was applied for the full-scale remediation of pyrite ash-contaminated soil (ca. 24 000 m3), and a dedicated sampling and analytical protocol was developed and implemented to verify if the treated material obtained complied with the general EoW criteria established by article 6 of the Waste Framework Directive 2008/98/EC. The results of the leaching, ecotoxicological, and mechanical tests carried out on representative samples of the treated soil showed that this material (ca. 19 000 m3) could be classified as EoW and thus was deemed reusable both in-situ as filler for the excavation and ex-situ as road construction material. These results improve the knowledge of the performance of a state-of-the-art technique for the treatment of metals-contaminated soil. Furthermore, the developed monitoring plan can support future assessments on the compliance of materials obtained from contaminated soil with the general EoW criteria