Highly effective and selective adsorption of thorium(IV) from aqueous solution using mesoporous graphite carbon nitride prepared by sol-gel template method

Abstract Selective separation of thorium resources from aqueous solutions is an ideal strategy for recovering or removing radioactive ions, as well as reducing potential human health and environmental risks. In this study, an effective adsorbent, mesoporous graphite carbon nitride (mpg-C3N4), was synthesized by a simple thermal condensation using a sacrificial LUDOX HS-40 colloidal silica as template and applied to the selective adsorption of thorium ions from the multi-ion solutions. The results of competitive experiments illustrated that mpg-C3N4/r exhibited higher selectivity and efficiency for Th(IV) over other 14 co-existing cations, with the maximum selective adsorption capacities of Th(IV) reaching to 108.18 mg g−1 for mpg-C3N4/r=1.0 which is more than g-C3N4 (36.64 mg g−1) at pH 4.0. The interaction of Th(IV) with mpg-C3N4/r=1.0 and g-C3N4 were performed using batch processing, the adsorption isotherm was well conformed to the Langmuir adsorption model, and the maximum adsorption capacity of thorium at pH 4.0 and 298 K was calculated to be 196.08 mg g−1 which is more than three times of g-C3N4 (60.60 mg g−1). Also, the results of adsorption experiments on monazite leachate showed that mpg-C3N4/r=1.0 can be successfully used as an attractive adsorbent with the high adsorption efficiency (93.53%) of thorium. This work could broaden insights into the tailored design and synthesis of mesoporous adsorbents for the selective adsorption of thorium in multi-ion solutions.