Enhanced degradation of organic contaminants using catalytic activity of carbonaceous structures:A strategy for the reuse of exhausted sorbents

Generation of hydroxyl radicals(·OH)is the basis of advanced oxidation process(AOP).This study investigates the catalytic activity of microporous carbonaceous structure for in-situ generation of·OH radicals.Biochar(BC)was selected as a representative of carbon materials with a graphitic structure.The work aims at assessing the impact of BC structure on the activation of H2O_(2),the reinforcement of the persistent free radicals(PFRs)in BC using heavy metal complexes,and the subsequent AOP.Accordingly,three different biochars(raw,chemically-and physiochemically-activated BCs)were used for adsorption of two metal ions(nickel and lead)and the degradation of phenol(100 mg/L)through AOP.The results demonstrated four outcomes:(1)The structure of carbon material,the identity and the quantity of the metal complexes in the structure play the key roles in the AOP process.(2)the quantity of PFRs on BC significantly increased(by 200%)with structural activation and metal loading.(3)Though the Pb-loaded BC contained a larger quantity of PFRs,Ni-loaded BC exhibited a higher catalytic activity.(4)The degradation efficiency values for phenol by modified biochar in the presence of H2O_(2) was 80.3%,while the removal efficiency was found to be 17%and 22%in the two control tests,with H2O_(2)(no BC)and with BC(no H2O_(2)),respectively.Overall,the work proposes a new approach for dual applications of carbonaceous structures;adsorption of metal ions and treatment of organic contaminants through in-situ chemical oxidation(ISCO).

A new perspective on ecological vulnerability and its transformation mechanisms

Ecological vulnerability refers to the degree of ecosystem disturbance,system damage,and the ability of system restoration.Although case-specific evaluations of ecological vulnerability are progressing rapidly,they have been carried out mainly in areas with intensive human activities or in harsh natural environments.Using the Web of ScienceTM core collection,this review paper summarized studies on ecological vulnerability published from 2000 to 2022 and analyzed in depth major case studies.It was found that traditional ecological vulnerability research has been addressed largely in terms of assessment models,data processing models,and analysis of influencing factors,however there was a lack of research on the process of vulnerability transformation.Because the vulnerability transformation in a hierarchical vulnerability index system is regulated by multiple factors in a heterogeneous region,it is urgent to understand how the ecological vulnerability in a region evolves from one level to another over time.Therefore this paper put forward the new perspective of research,i.e.,applying quantitative analysis to identification of regulating factors and exploring the mechanisms of ecological vulnerability transformation.This new perspective could assist in monitoring the complex spatiotemporal changes in ecological vulnerability and taking necessary measures to prevent from decline of ecological stability.