One-step preparation of a novel graphitic biochar/Cu^(0)/Fe_(3)O_(4) composite using CO_(2)-ambiance pyrolysis to activate peroxydisulfate for dye degradation

Herein,a one-step co-pyrolysis protocol was adopted for the first time to prepare a novel pyrogenic carbon-Cu^(0)/Fe_(3)O_(4)heteroatoms (FCBC) in CO_(2)ambiance to discern the roles of each component in PDS activation.During co-pyrolysis,CO_(2)catalyzed formation of reducing gases by biomass which facilitated reductive transformation of Fe^(3+)and Cu^(2+)to Cu^(0)and Fe_(3)O_(4),respectively.According to the analysis,the resulting metal (oxide) catalyzed graphitization of biocharand decomposition of volatile substances resulting in an unprecedented surface area (1240 m^(2)/g).The resulting FCBC showed greater structural defects and less electrical impedance.Batch experiments indicated that Rhodamine B (RhB) degradation by FCBC (100%) was superior to Fe_(3)O_(4)(50%) and Cu^(0)/Fe_(3)O_(4)(76.4%) in persulfate (PDS) system,which maintained reasonable efficiency (75.6%-63.6%) within three cycles.The reactive oxygen species (ROS) associated with RhB degradation was identified by an electron paramagnetic resonance and confirmed by scavenging experiments.RhB degradation invoked both(sulfate and dominantly hydroxyl) radical and non-radical (singlet oxygen,^(1)O_(2)) pathways.Regarding FCBC,Cu^(0)can continuously react with Fe^(3+)in Fe_(3)O_(4)to generate larger quantities of Fe^(2+),and both Cu^(0)and Fe^(2+)activated PDS to yield sulfate radicals which was quickly converted to hydroxyl radical.Besides,Cu^(0)/Cu^(2+)could complex with PDS to form a metastable complex,which particularly contributed to1O_(2)generation.These cascade reactions by FCBC were reinforced by carbonyl group of biochar and favorable electron transfer ability.This work highlighted a new approach to prepare a magnetic and environment-benign heterogonous catalyst to remove organic pollutants in water.

Reimagining safe lithium applications in the living environment and its impacts on human,animal,and plant system

Lithium's(Li)ubiquitous distribution in the environment is a rising concern due to its rapid proliferation in the modern electronic industry.Li enigmatic entry into the terrestrial food chain raises many questions and uncertainties that may pose a grave threat to living biota.We examined the leverage existing published articles regarding advances in global Li resources,interplay with plants,and possible involvement with living organisms,especially humans and animals.Globally,Li concentration(<10 e300 mg kg
1)is detected in agricultural soil,and their pollutant levels vary with space and time.High mobility of Li results in higher accumulation in plants,but the clear mechanisms and specific functions remain unknown.Our assessment reveals the causal relationship between Li level and biota health.For example,lower Li intake(<0.6 mM in serum)leads to mental disorders,while higher intake(>1.5 mM in serum)induces thyroid,stomach,kidney,and reproductive system dysfunctions in humans and animals.However,there is a serious knowledge gap regarding Li regulatory standards in environmental compartments,and mechanistic approaches to unveil its consequences are needed.Furthermore,aggressive efforts are required to define optimum levels of Li for the normal functioning of animals,plants,and humans.This review is designed to revitalize the current status of Li research and identify the key knowledge gaps to fight back against the mountainous challenges of Li during the recent digital revolution.Additionally,we propose pathways to overcome Li problems and develop a strategy for effective,safe,and acceptable applications.

Response of microbial communities to biochar-amended soils:a critical review

Application of biochar to soils changes soil physicochemical properties and stimulates the activities of soil microorganisms that influence soil quality and plant performance.Studying the response of soil microbial communities to biochar amendments is important for better understanding interactions of biochar with soil,as well as plants.However,the effect of biochar on soil microorganisms has received less attention than its influences on soil physicochemical properties.In this review,the following key questions are discussed:(i)how does biochar affect soil microbial activities,in particular soil carbon(C)mineralization,nutrient cycling,and enzyme activities?(ii)how do microorganisms respond to biochar amendment in contaminated soils?and(iii)what is the role of biochar as a growth promoter for soil microorganisms?Many studies have demonstrated that biochar-soil application enhances the soil microbial biomass with substantial changes in microbial community composition.Biochar amendment changes microbial habitats,directly or indirectly affects microbial metabolic activities,and modifies the soil microbial community in terms of their diversity and abundance.However,chemical properties of biochar,(especially pH and nutrient content),and physical properties such as pore size,pore volume,and specific surface area play significant roles in determining the efficacy of biochar on microbial performance as biochar provides suitable habitats for microorgan-isms.The mode of action of biochar leading to stimulation of microbial activities is complex and is influenced by the nature of biochar as well as soil conditions.

Removal of toxic elements from aqueous environments using nano zero-valent iron-and iron oxide-modified biochar:a review

Biochar(BC)has gained attention for removal of toxic elements(TEs)from aqueous media;however,pristine biochar often exhibits low adsorption capability.Thus,various modification strategies in BC have been developed to improve its removal capability against TEs.Nanoscale zero-valent iron(nZVI)and iron oxides(FeOx)have been used as sorbents for TE removal.However,these materials are prone to agglomeration and also expensive,which make their usage limited for large-scale applications.The nZVI technical demerits could be resolved by the development of BC-based composite sorbents through the loading of nZVI or FeOx onto BC surface.Nano zero-valent iron modified BC(nZVIBC),FeOx-modified BC(FeOxBC)have attracted attention for their capability in removing pollutants from the aqueous phases.Nonetheless,a potential use of nZVIBC and FeOxBC for TE removal from aqueous environments has not been well-realized or reviewed.As such,this article reviews:(i)the preparation and characterization of nZVIBC and FeOxBC;(ii)the capacity of nZVIBC and FeOxBC for TE retention in line with their physicochemical properties,and(iii)TE removal mechanisms by nZVIBC and FeOxBC.Adopting nZVI and FeOx in BC increases its sporptive capability of TEs due to surface modifications in morphology,functional groups,and elemental composition.The combined effects of BC and nZVI,FeOx or Fe salts on the sorption of TEs are complex because they are very specific to TEs.This review identified significant opportunities for research and technol-ogy advancement of nZVIBC and FeOxBC as novel and effective sorbents for the remediation of TEs contaminated water.

Arsenic removal from water and soils using pristine and modified biochars

Arsenic(As)is recognized as a persistent and toxic contaminant in the environment that is harmful to humans.Biochar,a porous carbonaceous material with tunable functionality,has been used widely as an adsorbent for remediating As-contaminated water and soils.Several types of pristine and modified biochar are available,and significant efforts have been made toward modifying the surface of biochars to increase their adsorption capacity for As.Adsorption capacity is influenced by multiple factors,including biomass pyrolysis temperature,pH,the presence of dissolved organic carbon,surface charge,and the presence of phosphate,silicate,sulfate,and microbial activity.Improved As adsorption in modified biochars is attributed to several mechanisms including surface complexation/precipitation,ion exchange,oxidation,reduction,electrostatic interactions,and surface functional groups that have a relatively higher affinity for As.Modified biochars show promise for As adsorption;however,further research is required to improve the performance of these materials.For example,modified biochars must be eco-friendly,cost-effective,reliable,efficient,and sustainable to ensure their widespread application for immobilizing As in contaminated water and soils.Conducting relevant research to address these issues relies on a thorough understanding of biochar modifications to date.This study presents an in-depth review of pristine and modified biochars,including their production,physicochemical properties,and As adsorption mechanisms.Furthermore,a comprehensive evaluation of biochar applications is provided in As-contaminated environments as a guide for selecting suitable biochars for As removal in the field.