Equilibrium and kinetic studies of copper (II) ion uptake by modified wheat shells

Abstract

A B S T R AC TNatural adsorbents such as shells of unmodifi ed wheat (RW), and modifi ed wheat (MW) were assessed for Cu(II) adsorption from aqueous solutions. The removal of Cu(II) by these adsorbents from aqueous solution was investigated by using several parameters such as modifi ciation, contact time, temperature and pH. The extent of Cu(II) removal increased with increasing contact time, temperature and pH and also with modifi cation by Reactive Orange 122 of adsorbent. The experimental data were analysed by the Langmuir and Freundlich models of adsorption. It was found that the Freundlich equation fi ts better than the Langmuir equation. In addition, the adsorption data obtained at different temperatures of Cu(II) by adsorbents were applied to pseudo fi rst-order, pseudo second-order and Weber-Morris equations, and the rate constants of fi rst-order adsorption (k 1 ), the rate constants of second-order adsorption (k 2 ) and diffusion rate constants (k 3 ) at these temperatures were calculated, respectively. The rates of adsorption were found to conform to pseudo second-order kinetics with good correlation (R 2 ≥ 0.989). The data obtained from adsorption isotherms at different temperatures were used to calculate some thermodynamic quantities such as free energy of adsorption (ΔG°), enthalpy (ΔH°), and entropy (ΔS°). It is found that ΔG° is negative, indicating that the nature of adsorption process for Cu(II) is spontaneous. The positive value of ΔH° indicates that the adsorption of Cu(II) onto adsorbents is an endothermic process. The positive value of ΔS° refl ects the affi nity of the adsorbent for Cu(II). As a result, the present work indicates that the wheat shells MW chemically by Reactive Orange 122, possess more effi ciency in adsorbing Cu(II) ions than the unmodifi ed one (RW).

Sorption Properties of the Filter Material MS in Relation to Copper(II) Ions

“…According to the data given in [4,5], the capacity of the monolayer of various mineral sorbents with respect to copper(II) ions lies in the range from 1.01 to 55.56 mg/g. Thus, the filter material MS in its sorption properties is comparable with other mineral sorbents.…”

Green Routes for the Development of Chitin/Chitosan Sustainable Hydrogels

“…In Table 3, a summary of different methods conventionally used for the preparation of hydrogels from chitin is reported. Chitosan-based physical hydrogels (as summarized in Table 4) are normally obtained by combining its acidic solution with an alkaline medium containing a physical cross-linker, such as Sodium Citrate (SC), Tripolyphosphate (TPP), and β-Glycerophosphate (β-GP) [81][82][83][84][85][86][87][88][89]. [81] Hydrogel low stability TPP Drop in 10 wt% TPP (RT)/Cure (RT, 12 h) [82] Hydrophobic…”

Utilization ofMentha arvensiswaste biomass for the removal of Pb(II) and Co(II) from aqueous solutions

“…Biomasses have the ability to adsorb metal ions due to different functional groups of macromolecules such as polysaccharides, proteins, and lignin [10,17]. The biosorption of metal ions to the biomass surface occurs mainly as a result of either physical binding involving London forces or electrostatic attraction, or chemical binding such as binding between the adsorbent and the adsorbate [11].…”

“…A number of advantages associated with biosorption over other conventional techniques include simple and toxic sludge-free operation, low cost, and high selectivity [7]. Lead, one of the nonessential metal ions, is the third most toxic priority metal pollutant [8] listed by EPA and directly enters into water bodies through the effluent discharges including lead storage battery manufacturing, paper and pulp industries, mining operations, and smelting and metallurgical finishing processes [9][10][11][12]. Extensive reports and reviews are available on the toxicity of lead due to its excessive intake leading to immunological, neurological, developmental, reproductive, genotoxic, and carcinogenic effects.…”