Biochars derived from carp residues:characteristics and copper immobilization performance in water environments

Heavy metal pollution has attracted worldwide attention because of its adverse impact on the aquatic environment and human health.The production of biochar from biowaste has become a promising strategy for managing animal carcasses and remediating heavy metal pollution in the aquatic environment.However,the sorption and remediation performance of carp residue-derived biochar(CRB)in Cu-polluted water is poorly understood.Herein,batches of CRB were prepared from carp residues at 450–650℃(CRB450–650)to investigate their physicochemical characteristics and performance in the sorption and remediation of Cu-polluted water.Compared with a relatively low-temperature CRB(e.g.,CRB450),the high-temperature biochar(CRB650)possessed a large surface area and thermodynamic stability.CRB650 contained higher oxygen-containing functional groups and P-associated minerals,such as hydroxyapatite.As the pyrolytic temperature increased from 450 to 650℃,the maximum sorption capacity of the CRBs increased from 26.5 to 62.5 mg/g.The adsorption process was a type of monolayer adsorption onto homogenous materials,and the sorption of Cu^(2+)on the CRB was mainly based on chemical adsorption.The most effective potential adsorption mechanisms were in order of electrostatic attraction and cation-πinteraction>surface complexation and precipitation>pore-filling and cation exchange.Accordingly,the CRBs efficiently immobilized Cu^(2+)and reduced its bioavailability in water.These results provide a promising strategy to remediate heavy metal-polluted water using designer biochars derived from biowastes,particularly animal carcasses.

Resource utilization of typical biomass wastes as biochars in removing plasticizer diethyl phthalate from water: characterization and adsorption mechanisms

Plastic pollution as a global environmental issue has become a research hotspot,among which the removal of inherent plasticizer(e.g.,phthalic acid esters,PAEs)received increasing attention.However,the effects of biochars derived from different feedstocks on the adsorption of PAEs are poorly understood.Thus,the characteristics of biochars derived from six largely produced biomass wastes in China at 400°C,as well as their performance in adsorption of diethyl phthalate(DEP),one of frequently detected PAEs in aqueous environment,were investigated.The results indicated that the variation in feedstock type showed significant changes in the properties(e.g.,porosity,specific surface area,surface functional groups)of biochars,which affected DEP adsorption and desorption.Pseudosecond order and Freundlich models fitted the adsorption data well,and adsorption mechanisms mainly included hydrophobic effect,followed by micropore filling,hydrogen bonding,andπ-πEDA interactions.Adsorption thermodynamics revealed that the adsorption was a spontaneous and exothermic the adsorption capacities of DEP on these biochars slightly decreased with the increasing pH but increased with the increasing ionic strength.Among these biochars,the giant reed biochar with relatively higher DEP adsorption and low desorption exhibited the great efficiency for DEP removal as an environment-friendly sorbent.These results highlighted the significant roles of micropore filling and hydrogen bond in determining adsorption capacity of designed biochars prepared from selecting suitable agricultural straws and wetland plant waste to typical plasticizer.The findings are useful for producing designed biochars from different biomass wastes for plasticizer pollution control.

Biochar application in remediating salt-affected soil to achieve carbon neutrality and abate climate change

Salt-affected soils urgently need to be remediated to achieve the goals of carbon neutrality and food security.Limited reviews are available on biochar performance in remediating salt-affected soils in the context of carbon neutrality and climate change mitigation.This work summarized the two pathways to achieve carbon neutrality during remediating salt-affected soils using biochars,i.e.,biochar production from sustainable feedstock using thermal technologies,application for promoting plant productivity and mitigating greenhouse gas(GHG)emission.Converting biomass wastes into biochars can reduce GHG emission and promote carbon dioxide removal(CDR),and collection of halophyte biomass as biochar feedstocks,development of biochar poly-generation production systems with carbon neutrality or negativity could be promising strategies.Biochar can effectively improve plant growth in salt-affected soils,showing that the grand mean of plant productivity response was 29.3%,via improving physicochemical characteristics,shifting microbial communities,and enhancing plant halotolerance.Moreover,biochar can mitigate GHG emission via inducing negative priming effect,improving soil properties,changing microbial communities associated with carbon and nitrogen cycle,direct adsorption of GHG.However,biochar also may pose negative effects on plant growth because of stress of toxic compounds and free radicals,and deterioration of soil properties.The promoted GHG emission is mainly ascribed to positive priming effect,and provision of labile carbon and inorganic nitrogen fractions as microbial substrates.Finally,this review pointed out the gaps in the current studies and the future perspectives.Particularly,the development of“carbon neutral”or“carbon negative”biochar production system,balancing the relationship of biochar effectiveness and functionality with its environmental risks and costs,and designing biochar-based GHG adsorbents would be important directions for remediating salt-affected soils to achieve carbon neutrality and abate climate change.

Data quality assessment for studies investigating microplastics and nanoplastics in food products: Are current data reliable?

Data on the occurrence of microplastics and nanoplastics(MP/NPs)in foods have been used to assess the human health risk caused by the consumption of MP/NPs.The reliability of the data,however,remains unclear because of the lack of international standards for the analysis of MP/NPs in foods.Therefore,the data quality needs to be assessed for accurate health risk assessment.This study developed 10 criteria applicable to the quality assessment of data on MP/NPs in foods.Accordingly,the reliability of 71 data records(69 of them only focused on MPs)was assessed by assigning a score of 2(reliable without restrictions),1(reliable but with restrictions),or 0(unreliable)on each criterion.The results showed that only three data records scored 2 or 1 on all criteria,and six data records scored 0 on as many as six criteria.A total of 58 data records did not include information on positive controls,and 12 data records did not conduct the polymer identification,which could result in the overestimation or underestimation of MP/NPs.Our results also indicated that the data quality of unprocessed foods was more reliable than that of processed foods.Furthermore,we proposed a quality assurance and quality control protocol to investigate MP/NPs in foods.Notably,the characteristics of MP/NPs used in toxicological studies and those existing in foods showed a remarkable discrepancy,causing the uncertainty of health risk assessment.Therefore,both the estimated exposure of MP/NPs and the claimed potential health risks should be treated with caution.

Regioselective oxidation of tetracycline by permanganate through alternating susceptible moiety and increasing electron donating ability

Permanganate has attracted much attention in wide range of chemistry and particularly in degradation of environmental pollutants.However,few studies have discussed the feature of regioselective reactivity of permanganate with specific moiety of the target compound.Herein,we studied the reaction between permanganate and tetracycline that is an emerging micropollutant with different species containing several electron-rich groups.The second-order rate constants increased from 6.0 to 9.0 and could be quantitatively modeled by considering the speciation of both reactants,yielding kTC0=11.7(mol/L)^-1 sec^-1,kTC-=35.7(mol/L)^-1 sec^-1,kTC2-=43.1(mol/L)^-1 sec^-1 for individual reaction channels.Degradation products were then identified as the hydroxylated and demethylated compounds.The result suggested a rate-limiting step of simple hydroxylation at the phenolic and/or alkene moieties,while the demethylation should be caused by the unavoidably formed manganese oxide via single electron oxidation.This is supported by the DFT calculation,indicating the primary oxidation of phenolic group of TC0 with activation barrier of 44.5 kcal/mol and of alkene group of TC-and TC2-with activation barriers of 44.0 and 43.4 kcal/mol,respectively.This is in agreement with the experimental results,implying the alternation of regioselectivity associated with the deprotonation process.The result was further supported by performing the Fukui function and electrostatic potential analysis,reflecting the more probable site and better electron donating tendency beneficial to the permanganate oxidation.

Allelopathic inhibition on red tide microalgae Skeletonema costatum by five macroalgal extracts

This study aims to identify effective antialgal allelochemicals from marine macroalgae that inhibit the growth of red tide microalgae.Practically,new algicidal agents were developed to control red tide.The growth inhibitory effects of 5 marine macroalgae Porphyra tenera,Laminaria japonica,Ulva pertusa,Enteromorpha clathrata,and Undaria pinnatifida on Skeletonema costatum were evaluated by adding crude seawater extracts of macroalgal dry tissue into the culture medium containing S.costatum.The half-effective concentrations at 120 h(EC_(50),120 h)of the seawater extracts were 0.6,0.9,1.0,1.0,and 4.7 g/L for the five macroalgae above,respectively.E.clathrata,L.japonica and U.pertusa showed strong allelopathic effect on the growth of S.costatum.There have been no previous reports with regard to the allelopathic effects of the former two macroalgae so far.The possible allelochemicals of 21 compounds of the E.clathrata were detected using Gas chromatography-mass spectrometry(GC-MS)analysis.Unsaturated fatty acids,acrylic acid(C_(3)H_(4)O_(2)),and linolenic acid(C_(18)H_(30)O_(2))were the most likely allelochemicals in E.clathrata.

Rhizosphere effect of different aquatic plants on phosphorus depletion

A series of pot experiments with Alternanthera philoxeroides,Typha latifolia,Sagittaria sagittifolia and Phragmites communis were conducted to assess the phosphorus depletion effect in the rhizosphere.The ratio of root to shoot,root morphology,phosphorus uptake efficiency and phosphorus utilization efficiency were analyzed.An obvious variation in phosphorus concentrations between the rhizosphere soil and non-rhizosphere soil was observed.The water-soluble P contents in the rhizosphere soil of A.philoxeroides,T.latifolia,S.sagittifolia and P.communis were reduced by 81%,42%,18%and 16%,respectively,compared with that in the non-rhizosphere soil.A.philoxeroides had the highest phosphorus uptake efficiency(1.32 mg/m),while T.latifolia achieved the effective phosphorus depletion by the strong rooting system and the high phosphorus uptake efficiency(0.52 mg/m).T.latifolia not only used phosphorus to produce biomass economically,but also adjusted carbon allocation to the roots to explore the soil for more available phosphorus.A.philoxeroides and T.latifolia were more effective in depleting phosphorus in the rhizosphere than S.sagittifolia and P.communis.