The preparation and performance of lignin-based activated carbon fiber adsorbents for treating gaseous streams

Two types of lignin-based carbon fibers were prepared by electrospinning method. The first was activated with Fe304 （LCF-Fe）, and the second was not activated with Fe3O4 （LCF）. Gas phase adsorption isotherms for toluene on LCF-Fe and LCF were studied. The gas phase adsorption isotherm for 0% RH showed LCF-Fe have about 439 mg/g adsorption capacity which was close to that of commercially available activated carbon （500 rag/g）. The Dubinin-Radushkevich equation described the isotherm data very well. Competitive adsorption isotherms between water vapor and toluene were measured for their RH from 0 to 80%. The effect of humidity on toluene gas-phase adsorption was predicted by using the Okazaki et al. model. In addition, a constant pattern homogeneous surface diffusion model （CPHSDM） was used to predict the toluene breakthrough curve of continuous flow-packed columns containing LCF-Fe, and its capacity was 412 mg/g. Our study, which included material characterization, adsorption isotherms, kinetics, the impact of humidity and fixed bed performance modeling, demonstrated the suitability of lignin-based carbon fiber for volatile organic compound removal from gas streams .

Microbial mediated arsenic biotransformation in wetlands

Arsenic （As） is a pervasive environmental toxin and carcinogenic metalloid. It ranks at the top of the US priority List of Hazardous Substances and causes worldwide human health problems. Wetlands, including natural and artificial ecosystems （i.e. paddy soils） are highly susceptible to As enrichment; acting not only as repositories for water but a host of other elemental/chemical moieties. While macroscale processes （physical and geological） supply As to wetlands, it is the micro-scale biogeochemistry that regulates the fluxes of As and other trace elements from the semi-terrestrial to neighboring plant/ aquatic/atmospheric compartments. Among these fine-scale events, microbial mediated As biotransformations contribute most to the element＇s changing forms, acting as the ＇switch＇ in defining a wetland as either a source or sink of As. Much of our understanding of these important microbial catalyzed reactions follows relatively recent scientific discoveries. Here we document some of these key advances, with focuses on the implications that wetlands and their microbial mediated transformation pathways have on the global As cycle, the chemistries of microbial mediated As oxidation, reduction and methylation, and future research priorities areas.

Ultrastable MOF-based foams for versatile applications

Metal-organic frameworks(MOFs)are attractive for promising applications but plagued by difficult recovery and deployment due to their intrinsic nano/micro powder nature.Although significant efforts have been made to develop separable solid matrixes for MOF supporting,the poor loading stability and durability of MOFs still challenge their engineering applications.Here,we present a facile and effective approach to fabricate MOF-based melamine foams(MFs)(denoted as MOFiths)with ultrahigh loading stability and operation stability,easy separation,and high-efficient performance for versatile robust applications.By adopting our approach,numbers of typical fragile MOFs characterized with wide ranges of particle size(from~nm to~μm)can be precisely incorporated into MFs with controllable loading ratios(up to~1,600%).Particularly,the produced MOFiths show excellent capacities for the highly effective and durable water purifications and acetalization reactions.100%of organic pollutants can be rapidly destructed within 10 min by MOFiths initiated Fenton or catalytic ozonation processes under five successive cycles while the maximum adsorption capacity of MOFiths toward Pb(II),Cd(II),and Cu(II)reaches to 422,222,and 105 mg·g^(-1),respectively.This study provides a critical solution to substantially facilitate the engineering applications of MOFs for long-term use in practice.