Tb^(3+)-nucleic acid probe-based label-free and rapid detection of mercury pollution in food

Mercury is a threatening pollutant in food,herein,we developed a Tb^(3+)-nucleic acid probe-based label-free assay for mix-and-read,rapid detection of mercury pollution.The assay utilized the feature of light-up fluorescence of terbium ions(Tb^(3+))via binding with single-strand DNA.Mercury ion,Hg^(2+)induced thymine(T)-rich DNA strand to form a double-strand structure(T-Hg^(2+)-T),thus leading to fluorescence reduction.Based on the principle,Hg^(2+)can be quantified based on the fluorescence of Tb^(3+),the limit of detection was 0.0689μmol/L and the linear range was 0.1-6.0μmol/L.Due to the specificity of T-Hg^(2+)-T artificial base pair,the assay could distinguish Hg^(2+)from other metal ions.The recovery rate was ranged in 98.71%-101.34%for detecting mercury pollution in three food samples.The assay is low-cost,separation-free and mix-to-read,thus was a competitive tool for detection of mercury pollution to ensure food safety.

High surface area and mesoporous activated carbon from KOH-activated dragon fruit peels for methylene blue dye adsorption:Optimization and mechanism study

In this study,an alternative precursor for production of activated carbon was introduced using dragon fruit(Hylocereus costaricensis)peel(DFP).Moreover,KOH was used as a chemical activator in the thermal carbonization process to convert DFP into activated carbon(DFPAC).In order to accomplish this research,several approaches were employed to examine the elemental composition,surface properties,amorphous and crystalline nature,essential active group,and surface morphology of the DFPAC.The BrunauerEmmettTeller test demonstrated a mesoporous structure of the DFPAC has a high surface area of 756.3 m2g 1.The cationic dye Methylene Blue(MB)was used as a probe to assess the efficiency of DFPAC towards the removal of MB dye from aqueous solution.The effects of adsorption input factors(e.g.DFPAC dose(A:0.040.12 g L 1),pH(B:310),and temperature(C:3050℃))were investigated and optimized using statistical analysis(i.e.BoxBehnken design(BBD)).The adsorption kinetic model can be best categorized as the pseudofirst order(PFO).Whereas,the adsorption isotherm model can be best described by Langmuir model,with maximum adsorption capacity of DFPAC for MB dye was 195.2 mg g 1 at 50℃.The adsorption mechanism of MB by DFPAC surface was attributed to the electrostatic interaction,pp interaction,and Hbonding.Finally,the results support the ability of DFP to be a promising precursor for production of highly porous activated carbon suitable for removal of cationic dyes(e.g.MB).

Vine pruning waste-based activated carbon for cerium and lanthanum adsorption from water and real leachate

In this study,vine pruning wastes(VPW)were used as raw material to develop an alternative activated carbon(VPW-AC)for adsorbing and concentrating rare earth elements cerium(Ce(Ⅲ))and lanthanum(La(Ⅲ))from synthetic and real leachate solutions.The Ce and La adsorption studies evaluated the effects of VPW-AC dosage,pH,contact time,rare earth initial concentration,and temperature.The VPW-AC adsorbent was subjected to many physicochemical characterization methods to correlate and understand its adsorptive performance.The characterization data indicate a carbonaceous adsorbent with a specific surface area of 467 m^(2)/g.Zeta potential indicates a material with a negatively charged surface at a pH higher than 3.1,which is extremely beneficial to cations removal.For both rare earths elements(REEs),the adsorption capacity increases with the increase of the pH,reaching its maximum at pH 4-6.The kinetic data are well fitted by Avrami-fractional o rder,while the Liu model agreeably fits equilibrium data.The maximum adsorption capacities for Ce(Ⅲ)and La(Ⅲ)are 48.45 and 53.65 mg/g at 298 K,respectively.The thermodynamic studies suggest that the adsorption process is favorable,spontaneous,and exothermic for both REEs.Pore filling,surface complexation,and ion exchange are the dominant mechanisms.Finally,the VPW-AC was subjected to the recovery of REEs from real phosphogypsum leachate,and it is proved that it can be successfully used to recover REEs in a real process.