4-Aminoacetophenone Intercalated CoAl Layered Double Hydroxides: Synthesis, Characterization and Adsorptive Removal of Cd(II) ions from Water Samples

In the present study, CoAl-NO3 Layered Double Hydroxides (CoAl-NO3-LDH) was synthesized and an enolate anion of 4-Aminoacetophenone (AAP) was intercalated into LDH following the reconstruction approach. The CoAl-NO3-LDH and CoAl-AAP-LDH were characterized by Fourier-Transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive X-ray (EDX) analyses. CoAl-AAP-LDH worked well for adsorption of Cd(II) ions from aqueous samples at optimum pH 7, adsorbent dosage 25 mg, concentration of Cd(II) ions 25 mg L-1 and shaking time 20 min at 25 °C. Different isotherms such as Langmuir, Freundlich and Dubinin-Radushkevich (D-R) isotherms fitted well to adsorption data with correlation coefficient (R2) of 0.998, 0.982 and 0.992, respectively. Monolayered (Qm) and multi-layered (KF) capacities of CoAl-AAP-LDH for adsorption of Cd(II) ions were calculated and found to be 34.40 and 19.44 mg g-1, respectively. Sorption energy was calculated and found to be 9.13 kJ mol-1, indicating chemisorption or ion exchange sorption mechanism. The method worked well for the adsorption of Cd(II) ions from wastewater samples.

Equilibrium and Thermodynamic Investigation of Biosorption of Nickel from Water by Activated Carbon Made from Palm Kernel Chaff

Novel biosorbents were derived from a waste product of palm kernel oil extraction known a palm kernel chaff (PKC). One portion of the PKC was carbonized in a furnace and then activated chemically while the other half was activated without carbonization. Both were designated as CPKC and UPKC respectively. The two biosorbents so produced were then used to conduct batch equilibrium sorption studies at 30 ºC, 35 ºC and 40 ºC and pH 3.0 and 9.0. The Koble-Corrigan, Dubinin-Radushkevich and the Freundlich isotherms fitted the experimental data very well with R2 values of 0.97 to 1.0, 0.95 to 1.0 and 0.96 to 1.0 respectively. The linear type II Langmuir isotherm performed much better (0.96 ≤ R2 ≤ 1.0) than the nonlinear isotherm. The maximum sorption capacity was obtained as 120.6 mg/g using CPKC at pH 9.0 and 35ºC. The values of Langmuir separation coefficient (0.022 ≤ RL≤0.926) show that the sorption of nickel to PKC is favourable. The most favourable sorption condition was found for CPKC at pH 9 and temperature of 40 ºC. The values of sorption energy (8.21 ≤ E ≤ 14.27) and the isosteric heat of sorption (-133.09≤∆Hx≤-17.92) indicate that the mode of sorption is mostly ion exchange. Thermodynamic parameters also show that the process is exothermic and entropy-driven.

The Use of Biomass of Apricot Kernels as a Material for the Extraction of Methylene Blue from Aqueous Media

The possibility of using a sorption material based on apricot kernels for the extraction of methylene blue (MG) dye from aqueous media is considered. The maximum sorption capacity of the material was established – 0.58 mmol/g (185.6 mg/g). The obtained isotherm was processed within the framework of monomolecular and polymolecular adsorption models. The equations that most accurately describe the isotherm are determined, and the correlation coefficients are calculated. It has been shown that the sorption isotherm of the MG dye by the crushed apricot kernel (CCA) is best described by the Langmuir (R2 = 0.9724) and Dubinin-Radushkevich (R2 = 0.9818) models. However, when comparing the plots of the function A = f(Ce) of the sorption processes of the dye by the CCA sorbent according to the models under study with the experimental dependence, it was found that the sorption process is most accurately described by the sorption models of Dubinin-Radushkevich and Temkin. Using the equations of the Langmuir and Dubinin-Radushkevich models, the thermodynamic parameters of the process were calculated: the sorption energy (E = 8.066 kJ/ mol) and the Gibbs energy (∆Go = -8.597 kJ/mol).

Kinetics and Isotherms of an Iron-Modified Montmorillonite/Polycaprolactone Composite Nanofiber Membrane for the Adsorption of Cu(II) Ions

Exposure to toxic concentrations of Cu (II) continues to rise as developing countries undergo rapid industrialization. Because of its high solubility in water, improperly disposed copper contaminate our water sources in its aqueous Cu (II) form. A nanofiber membrane composed of iron-modified montmorillonite (Fe-MMt) dispersed in polycaprolactone (PCL) was electrospun for the adsorption of Cu (II) ions. Kinetics and isotherm models were used to study the adsorption behavior of the fabricated membrane. The adsorption capacity of this membrane was observed as a function of increasing contact time and initial Cu (II) ion concentration. Kinetic studies showed that Cu (II) adsorption follows a pseudo-second order kinetic model, while isotherm studies determined the adsorption to be monolayer as described by the Langmuir isotherm. Furthermore, it was observed that the adsorption capacity increases with increasing contact time, and with increasing initial metal ion concentration up to a maximum value of 6.44 mgg-1. Lastly, the Dubinin-Kaganer-Radushkevich isotherm was used to calculate for the sorption energy and determine the type of adsorption. A sorption energy of-5.83 kJmol-1 was obtained, thus the adsorption was classified to be physical.

Adsorption of Acid Blue 113 using Nanocarbon Spheres and its Kinetic and Isotherm Studies

Nanocarbon spheres were prepared from the stems of Alternanthera sessilis. Their characterization studies were performed and the application of nanocarbon spheres for the adsorption of acid blue 113 from the aqueous solution was studied. Effect of pH of effluent, effect of initial acid blue 113 concentration and the effect of solution temperature were analyzed. Pseudo-first order model, pseudo-second order model, Elovich model, Intra-particle diffusion model, Langmuir model, Freundlich model and thermodynamic parameters were used to evaluate the percentage and the amount of acid blue 113 dye removed. The kinetics follows multi-order and Langmuir type of isotherm. The ΔG, ΔH and ΔS parameters which relate to sorption energy were also evaluated. The outcome of the study indicates that nanocarbon sphere is a potential material for the sorption of acid blue 113 with good efficiency.

Alumina as environmentally stable adsorbent for the removal of diresul black dye from waste water

Various adsorbents for the removal of dyes from waste water may or may not be stable, resulting in the desorption of adsorbed dyes with slight changes in physical conditions. To avoid this problem, environmentally stable adsorbent such as activated aluminum oxide or alumina has been used for the removal of Diresul Black, which is a dye used in the textile processing industry. Fourier-transform infrared spectroscopy confirms the non-tetrahedral framework of alumina. The efficiency of alumina via adsorption implies that 1 g alumina having the Brunauer–Emmett–Telle surface area of 2.65 ± 0.25 m2/g is enough to achieve up to 85% removal of concentrated dye solution in just 20 minutes. Adsorption energy as well as adsorption capacity is calculated by different adsorption isotherms. The sorption energy E turns out to be 19.3 KJ/mol. The thermodynamic studies show that the value of ΔH for the adsorption process is −976.5 J/mol while that of ΔS is −4.748 J/mol/K. Desorption studies show that the dye remains in its adsorbed form over aluminum oxide up to a pH of 2. Various ions present in the matrix interfere with the adsorption process, however none can decrease the adsorption below 65%.