ZIF-derived nitrogen-doped porous carbons as highly efficient adsorbents for removal of organic compounds from wastewater

Abstract

Dyes as one of organic pollutants have received increasing attention due to its harmful effects on many forms of life, in which methylene blue (MB) is often considered as a model organic pollutant for experimental measurement. In this work, we synthesize three ZIF-derived N-doped porous carbon adsorbents and further investigate their performance of removing MB from wastewater. Results indicate that MB saturated adsorption capacities of Carbon-ZD, Carbon-ZS, Carbon-Z are 1148.2, 791.3 and 505.3mg/g, respectively, which means that Carbon-ZD is a better MB adsorbent, compared to the other two. Moreover, when the excessive adsorbents are used to treat wastewater containing MB pollutant, Carbon-ZD can almost completely remove the MB pollutant, because the removal percent of Carbon-ZD is almost 100%, which means that Carbon-ZD is an excellent candidate for MB removal from wastewater. Further experiments indicate that Carbon-ZD also possesses excellent regeneration and reusability, as well as anti-interference ability when MO and MB pollutants coexist in wastewater. To explore adsorption kinetic and thermodynamics, we also found that the pseudo-second order model can satisfyingly describe MB adsorption kinetics and the Langmuir model can well describe MB adsorption isotherm. The excellent performance of Carbon-ZD for MB removal from wastewater is mainly attributed to the high BET specific surface area, suitable pore size distribution and nitrogen-doping. It is expected that the strategy of rationally designing ZIF or MOF template to prepare nitrogen-doped porous carbon adsorbents can open a new way to develop highly efficient adsorbents for removing pollutants in wastewater.