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Manganese is one of the heavy metals that is a major environmental concern when present in large amount. Manganese is discarded into water systems by numerous industries, including mining, batteries and electroplating etc. Pineapple leaves were applied as a biomass source to produce a magnetic hydrothermal treated hydochar nanocomposite; Fe3O4-HC. The BET surface area of Fe2O3-HC nanocomposite was 21.27 m2/g. Batch adsorption experiments revealed that the uptake of Mn2+ fit well in the pseudo second kinetics model, while the adsorption isotherm best fit the Freundlich model, with a maximum adsorption capacity of 2.99 mg/g at 25 °C and a pH of 5. The obtained thermodynamic parameters demonstrated that Mn2+ ion adsorption using the Fe2O3-HC nanocomposite was endothermic and nonspontaneous. Additionally, Fe2O3-HC nanocomposite demonstrated to be highly selective towards Mn2+ ions in the presence of other ions. The removal percentage of Mn2+ from a real water sample spiked with 50 mg/L Mn2+ was reported to be 53.2%. The spent adsorbent was then used to detect latent fingerprints, which revealed that Mn2+-Fe2O3-HC nanocomposite generated better and clear latent fingerprints than Fe2O3-HC nanocomposite.

In this study potassium salts such as KF, KCl and KBr were doped onto g-C3N4 to form KX-g-C3N4 (X = F, Cl and Br) via a thermal method. The KX-g-C3N4 was characterized by various instrumentation techniques such as UV–visible, FT-IR, XRD, Photoluminescence, TGA, BET, Raman, SEM, EDAX, HR-TEM, and Zeta potential. KX-g-C3N4 was explored for the photocatalytic degradation of methylene blue (MB) under visible light irradiation. Among them, KF-g-C3N4 showed excellent photocatalytic degradation of methylene blue (MB) under visible light irradiation. The KF-g-C3N4 significantly reduced the electrons–holes recombination rate when compared to KCl-g-C3N4, KBr-g-C3N4 and g-C3N4. The photocatalytic degradation mechanism was also studied with KF-g-C3N4.

Sulfur containing ion imprinted polymers (S-IIPs) were applied for the uptake of Hg(II) from aqueous solution. Cysteamine which was used as the ligand for Hg(II) complexation, was grafted along the epichlorohydrin crosslinked carboxylated carboxymethyl cellulose polymer chain through an amide reaction. The adsorption ability of S-IIPs towards Hg(II) was investigated by kinetic and isotherm models, which, corresponding, showed that the adsorption process followed a pseudo-second-order, fitted well with the Langmuir isotherm with a maximum adsorption capacity of 80 mg/g. Moreover, thermodynamic studies indicated an endothermic and spontaneous reaction with the tendency of an enhanced randomness at the surface of the S-IIPs with temperature increases. S-IIPs indicated a high degree of selectivity towards Hg(II) in the presence of Cu 2+ , Zn 2+ , Co 2+ , Pb 2+ and Cd 2+ . Furthermore, the efficiency of S-IIPs was also evaluated against real samples showing 86.78%, 91.88%, and 99.10% recovery for Hg(II) wastewater, ground water and tap water, respectively. In this study, the adsorbent was successfully regenerated for five cycles, which allows for their reuse without significant loss of initial adsorption capability., (Copyright © 2018. Published by Elsevier B.V.)

A new ion-imprinted polymer (IIP) was synthesized from sodium carboxymethyl cellulose and used for the adsorption of hexavalent chromium from aqueous solution. Epichlorohydrin was used to stabilize the polymer before ethylenediamine (EDA) ligand and Cr(VI) were introduced. The obtained IIP was characterized with FTIR, XPS, TGA, 13 C NMR, SEM, EDX, BET and zeta sizer. The kinetics of adsorption followed a pseudo-second-order model while the Langmuir adsorption isotherm provided the best fit with a maximum adsorption capacity of 177.62mg/g at 25°C. The Langmuir adsorption capacity for the non-imprinted polymer (NIP) at 25°C was 149.93mg/g. Thermodynamic parameters indicated an endothermic process and spontaneous adsorption of Cr (VI) on the polymers. IIP adsorbent was successfully recycled 5 times using 0.1M NaOH as a leachate; 98% Cr(VI) was desorbed during the last adsorption-desorption cycle., (Copyright © 2017. Published by Elsevier B.V.)