Evidence for the involvement of Fe(IV) in water treatment by Fe(III)-activated sulfite

Water contamination by emerging organic pollutants is calling for advanced methods of remediation such as iron-activated sulfite-based advanced oxidation. Sulfate radical, SO₄^??, and hydroxyl radical, ^?OH, are the primary reactive intermediates formed in the Fe(III)/sulfite system, yet the possible involvement of Fe(IV) produced from Fe(II) and persulfates is unclear. Here we explored the role of Fe(IV) in the Fe(III)/sulfite system by methyl phenyl sulfoxide (PMSO) probe assay, electron paramagnetic resonance spectra analysis, alcohol scavenging experiment, and kinetic simulation. Results show that PMSO is partially transformed into methyl phenyl sulfone (PMSO₂), thus evidencing Fe(IV) formation. The remaining degradation of PMSO is due to SO₄^?? and ^?OH. The contribution of Fe(IV) versus free radicals is progressively promoted when the Fe(III)-sulfite reaction proceeds, with an upper limit of 80–90%. The contribution of Fe(IV) versus free radicals increases with Fe(III) and sulfite dosages, and decreases with increasing pH. Overall, our findings demonstrate the involvement of Fe(IV) in the Fe-catalyzed sulfite auto-oxidation process.

     

Assessment of popular techniques for co-processing municipal solid waste in Chinese cement kilns

• Municipal solid waste (MSW) was fermented, screened, gasified, then co-processed. • Co-processing MSW in cement kilns could cause excessive pollutant emissions. • Bypass flue gas can be disposed of through the main flue system. • Popular MSW co-processing methods do not affect cement quality. Cement kiln co-processing techniques have been developed in the past 20 years in China, and more than 60 factories now use fermentation, screening, and gasification pre-treatment techniques to co-process municipal solid waste (MSW). There three complete MSW pre-treatment techniques, co-processing procedures, and environmental risk assessments have been described in few publications. In this study, we assessed the effectiveness of each technique. The results suggested that the pollutant content released by each pre-treatment technology was lower than the emission standard. To reveal the mechanisms of pollutant migration and enrichment, the substances in the kiln and kiln products are investigated. The input of co-processing materials (Co-M) produced by fermentation caused formation of polychlorinated dibenzo-p-dioxins and dibenzofuran (PCDD/Fs) in the bypass flue gas (By-gas) in excess of the regulatory standard. The Co-M input produced by the screening and gasifier technologies caused the total organic carbon (TOC) concentration to exceed the standard. In addition, the NO_x, TOC, and PCDD/Fs in the By-gas exceeded the regulatory standard. Raw meal was the primary chlorine and heavy metals input stream, and clinker (CK) and cement kiln dust (CKD) accounted for>90% of the total chlorine output stream. Flue gas and CKD were the primary volatile heavy metal (Hg) output streams. Greater than 70% of the semi-volatile heavy metals (Cd, Pb, Tl and Se) distributed in hot raw meal and bypass cement kiln dust. The low-volatility heavy metals were concentrated in the CK. These results indicated that co-processing techniques used in China still require improvement.     

Recent advances in antimony removal using carbon-based nanomaterials: A review

• The synthesis and physicochemical properties of various CNMs are reviewed. • Sb removal using carbon-based nano-adsorbents and membranes are summarized. • Details on adsorption behavior and mechanisms of Sb uptake by CNMs are discussed. • Challenges and future prospects for rational design of advanced CNMs are provided. Recently, special attention has been deserved to environmental risks of antimony (Sb) element that is of highly physiologic toxicity to human. Conventional coagulation and ion exchange methods for Sb removal are faced with challenges of low efficiency, high cost and secondary pollution. Adsorption based on carbon nanomaterials (CNMs; e.g., carbon nanotubes, graphene, graphene oxide, reduced graphene oxide and their derivatives) may provide effective alternative because the CNMs have high surface area, rich surface chemistry and high stability. In particular, good conductivity makes it possible to create linkage between adsorption and electrochemistry, thereby the synergistic interaction will be expected for enhanced Sb removal. This review article summarizes the state of art on Sb removal using CNMs with the form of nano-adsorbents and/or filtration membranes. In details, procedures of synthesis and functionalization of different forms of CNMs were reviewed. Next, adsorption behavior and the underlying mechanisms toward Sb removal using various CNMs were presented as resulting from a retrospective analysis of literatures. Last, we prospect the needs for mass production and regeneration of CNMs adsorbents using more affordable precursors and objective assessment of environmental impacts in future studies.     

Preparation and performance characterization of a new dust suppressant with a cross-linked network structure for use in open-pit coal mines

Environmental Science and Pollution Research - In an effort to control dust pollution in open-air environments such as pit coal mines and coal transportation systems, a new dust suppressant with a...     

Does leakage exist in China’s typical protected areas? Evidence from 13 national nature reserves

Environmental Science and Pollution Research - There is profound interest in knowing the degree to which the effectiveness of China’s nature reserves, and whether leakage is common around the...     

Accumulation of potentially toxic trace elements (PTEs) by native plant species growing in a typical gold mining area located in the northeast of Qinghai-Tibet Plateau

Environmental Science and Pollution Research - Though gold mines provide significant economic benefits to local governments, mining causes soil pollution by potentially toxic trace elements (PTEs)...     

Exploring volatility of carbon price in European Union due to COVID-19 pandemic

Environmental Science and Pollution Research - The European Union (EU) Emissions Trading System is the most important means for the EU to achieve carbon neutrality, but it has been severely...     

Acute lead acetate induces neurotoxicity through decreased synaptic plasticity-related protein expression and disordered dendritic formation in nerve cells

Environmental Science and Pollution Research - Lead (Pb) is a widespread environmental heavy metal that can damage the cerebral cortex and hippocampus, and reduce the learning and memory ability in...     

Nutrient and tetracycline removal from simulated biogas slurry and biogas upgrading by microalgae cultivation under different carbon nanotubes concentrations

Environmental Science and Pollution Research - The present study sought to determine the effects of multi-walled carbon nanotubes (MWCNTs) concentrations (0–10 mg L?1) on tetracycline...     

Preparation and evaluation of humic acid–based composite dust suppressant for coal storage and transportation

Environmental Science and Pollution Research - To mitigate environmental pollution caused by the escape of dust during coal storage and transportation, humic acid (HA) and grafted acrylamide (AM)...