Figures (9)  Tables (4)

    • Figure 1. 

      Schematic for the fabrication of CoFe2O4 nanoparticles and PPy/CoFe2O4 nanocomposite.

    • Figure 2. 

      (a) X-ray diffraction patterns of cobalt ferrite and polypyrrole coated cobalt ferrite nanocomposite. (b) FE-SEM image of cobalt ferrite. (c) FE-SEM image polypyrrole coated cobalt ferrite.

    • Figure 3. 

      (a) FTIR spectrum of synthesized PPy/CoFe2O4 and CoFe2O4. (b) pH's influence on PPy/CoFe2O4's zeta-potential.

    • Figure 4. 

      Impact of pH on adsorption capability of Pb(II) at contact time = 120 min, adsorbent dose = 0.16 g·L−1, T = 303 K, and Pb(II)] = 30 mg·L−1.

    • Figure 5. 

      Impact of adsorbent dose on adsorption capacity and % removal Pb(II) at contact time = 120 min, T = 303 K, pH = 8.0, and [Pb(II)] = 30 mg·L−1.

    • Figure 6. 

      (a) Impact of [Pb(II))] and contact duration on adsorption capability of Pb(II) at contact time = 120 min, T = 303 K, pH = 8.0, and adsorbent dose = 0.16 g·L−1. (b) Analysis of the efficacy of Pb(II) removal utilizing PPy/CoFe2O4, PPy, and CoFe2O4 at contact time = 120 min, adsorbent dose = 0.16 g·L−1, T = 303 K, pH = 8.0, and [Pb(II)] = 30 mg·L−1.

    • Figure 7. 

      (a) PFO kinetic study, (b) PSO kinetic study, (c) IPD diffusion kinetic study for adsorption of Pb(II) by PPy/CoFe2O4 at contact time = 120 min, T = 303 K, pH = 8.0, [Pb(II)] = 30 mg·L−1, and adsorbent dose = 0.16 g·L−1.

    • Figure 8. 

      (a) The relationship between Ce and Ce/Qe (Langmuir model). (b) The relationship between logCe and logQe (Freundlich model). (c) The relationship between lnCe and Qe (Temkin model).

    • Figure 9. 

      (a) Effect of solvent on regeneration of PPy/CoFe2O4. (b) PPy/CoFe2O4 reusability.

    • Kinetic models Variables Initial Pb(II) content (mg·l−1)
      15 30 60
      Pseudo-first order kinetic Qe (mg·g−1) 42.26 93.60 173.27
      R2 0.9582 0.9797 0.9672
      k1 (min−1) 0.0552 0.0532 0.0531
      Pseudo-second order kinetic k2 (g−1·mg−1·min−1) 3.07 × 10−3 1.43 × 10−3 7.54 × 10−4
      Qe (mg·g−1) 92.59 188.68 357.14
      R2 0.9995 0.9991 0.9989
      Qe (mg·g−1) [Experimental] 91.2 184.4 343.2

      Table 1. 

      Variables computed from the PSO, and PFO kinetic model.

    • Temp (K) ∆S# (kJ·mole−1) ∆H# (J·K−1 mole−1) ∆G# (kJ·mole−1)
      298 −128.2 − 42.2 − 2.4
      303 − 3.3
      308 − 4.5
      313 − 5.5
      318 − 6.6

      Table 2. 

      Thermodynamic variables for adsorptive removal of Pb(II) by PPy/CoFe2O4.

    • Isotherm Constant values
      Freundlich KF (mg·g−1 ) = 202.63; 1/n = 0.361; R2 = 0.8592
      Langmuir RL = 0.044 − 0.007; R2 = 0.9995; KL (L·mg−1) = 2.15;
      Qmax (mg·g−1) = 357.14
      Temkin B = 67.30; KT (L·g−1) = 32.46; R2 = 0.9415

      Table 3. 

      Freundlich, Langmuir, and Temkin isotherm constants.

    • Adsorbent pH Contact time (min) Qmax
      (mg·g−1)      		 Ref.
      Polyaniline/Fe3O4 9.0 120 111.11 [45]
      Polythiophene-coated rice husk ash nanocomposite 4.0 240 34.48 [46]
      Polyaniline Sn(IV) tungstomolybdate nanocomposite 6.0 60 44.64 [48]
      Fig sawdust activated carbon 4.0 120 80.64 [50]
      Sulfonated magnetic nano particle 7.0 1440 108.93 [51]
      Poly(acrylic acid)/bentonite nanocomposite -- 1440 93.01 [52]
      Amino-functionalized magnetic nanoadsorbent 5.0 60 40.1 [53]
      Ti(IV) iodovanadate cation exchange 6.0 120 18.8 [54]
      Palygorskite-iron oxide nanocomposite 5.0 720 26.7 [55]
      Chitosan-starch composite 3.46 300 99.01 [56]
      PPy/CoFe2O4 8.0 120 357.14 This work

      Table 4. 

      Competitive assessments of the adsorption capabilities of Pb(II) onto diverse adsorbent materials.