Scavenging of aqueous toxic organic and inorganic cations using novel facile magneto-carbon black-clay composite adsorbent

New magneto-carbon black-clay composite adsorbents derived from feldspar clay, acorn (Quercus robur) fruit pericarp have been developed for efficient removal of both organic (methylene blue- MB) and inorganic (Cd(II)) pollutants from aqueous solutions. The facile composite adsorbents prepared in a one pot process using two varying mass ratios of clay to carbon black of 0.5:1 (BMF-0.5) and 1:1 (BMF-1) exhibited higher cation exchange capacity (CEC) than any of the starting adsorbents. The rates of removal of MB were faster than for Cd(II) ions in both composites, and consequently, faster equilibrium (30 and 120 min, respectively). The pseudo -second order kinetic model described the adsorption data better suggesting that the removal mechanism involved electrostatic interactions. Surface adsorption (>= 56%) accounted for the bulk of cations removal on the BMF-0.5 composite, while adsorption on pores or within various partitions was dominant (>= 54%) on the BMF-1 adsorbent for both cations. The equilibrium data for both cations adsorption onto BMF-0.5 and BMF-1 fit the Langmuir-type adsorption isotherm implying that adsorption of both cations occurred on adsorption sites having equal affinity for these cations and with the formation of only monolayer cations on adsorbent surfaces at equilibrium. Cd(II) was more adsorbed than MB on the adsorbents while increase in temperature enhanced adsorption to an extent: 298 > 288>308 K. The adsorption capacities of BMF-0.5 and BMF-1 for both cations were approximately 14 and 16 mg/g, respectively. Pre- and post-adsorptive IR spectra study suggested that the positions of active interactions between the cations and the adsorbents involved surface functional groups such as the OH, -COO-, and -C-N groups. The composite adsorbents could be reused more than three times without significantly losing the cation adsorption efficiency. Thus, magneto-carbon black-clay composite is a promising adsorbent for removal of organic and inorganic pollutants from water. (C) 2018 Elsevier Ltd. All rights reserved.