Adsorption of Lead (II) from aqueous solutions onto activated carbon prepared from Algerian dates stones of Phoenix dactylifera.L (Ghars variety) by H3PO4 activation

Preparation and characterization of low-cost activated carbon from Moringa oleifera chemically activated using ZnCl2 for the adsorption of bisphenol A

The use of agricultural by-products such as Moringa oleifera plants is one effort to support the reduction of environmental pollution. Activated carbon produces from agricultural wastes is relatively less expensive and can replace traditional methods such as renewable as well as nonrenewable materials such as petroleum residue and coal. In this study, the removal of bisphenol A from aqueous media was studied using activated carbon produced from M. oleifera pods and peels. A batch adsorption study was carried out by varying the parameters of the adsorption process. A maximum removal percentage of 95.46% was achieved at optimum conditions of 2.5 g L^-1 adsorbent dose, pH 7, 60 min contact time and 20 mg L^-1 initial concentration of BPA. The BET surface areas of MOP, MOP-AC and MOP-ACZ were found to be 12.60, 4.10 and 45.96 m²/g, respectively. The experimental data were analyzed by Langmuir, Freundlich and Temkin adsorption isotherm models. Equilibrium data fitted well with the Langmuir isotherm with a maximum monolayer adsorption capacity of 20.14 mg g^-1. The rates of adsorption were found to conform to the pseudo-second-order kinetics with a good correlation. The results indicate that the M. oleifera activated carbon could be employed as a low-cost alternative to commercial activated carbon in the removal of BPA from water.

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 as 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 and kinetic sorption studies at 30 °C, 35 °C and 40 °C and pH 3.0 and 9.0 for an agitation period of 5, 10, 20, 40, 60, 90, and 120 min. 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 35 °C. The Langmuir separation coefficient values (0.022 ≤ R_L ≤ 0.926) show that the sorption of nickel to PKC is favorable. The most favorable sorption condition was found for CPKC at pH 9 and temperature of 40 °C. The values of sorption energy (8.21 ≤ E ≤ 14.27) and the isosteric heat of sorption (-133.09 ≤ ∆H_x ≤ -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 pseudo-second-order kinetic model shows the best correlation compared to the other kinetic models. The coefficient of correlation for the pseudo-second-order model was mostly within the range of 0.999-1.000 for 90% of all kinetic studies carried out.

Preparation and characterization of MCM-48/nickel oxide composite as an efficient and reusable catalyst for the assessment of photocatalytic activity

Mesoporous silica (MCM-48) was synthesized and used as a catalyst for supporting the nickel oxide photocatalyst. The loading of nickel oxide on MCM-48 results in a considerable reduction in the bandgap energy to 2.4 eV. MCM-48 was used as a catalyst and back-supporter for the nickel oxide to enhance its photocatalytic properties along with adsorption capacity. Therefore, the adsorption capacity of MCM-48/Ni₂O₃ was enhanced by 17.5% and 32.2% compared to Ni₂O₃ and MCM-48, respectively. Furthermore, the percentage of photocatalytic degradation was improved by approximately 68.2% relative to the free-standing Ni₂O₃. The MCM-48/Ni₂O₃ proved the chemisorption adsorption mechanism that happens in multilayer form through the heterogeneous surface. This through fixing such Ni₂O₃ particles over the nanoporous topography to provide more exposed hot adsorption and photocatalytic sites for the incident light photons. Therefore, supporting Ni₂O₃ catalytic particles onto MCM-48 produces a new category of photocatalytic systems with promising active centers for the efficient degradation of Congo red dye molecules.

Removal of Cu(II), Pb(II) and Cr(VI) ions from aqueous solution using amidoximated non-woven polyethylene-g-acrylonitrile fabric

Pre-irradiation method was applied to graft acrylonitrile (AN) onto non-woven polyethylene film. Graft yield reached 130% at 70 kGy radiation dose, 60% monomer concentration and 4 h reaction time when H₂SO₄ was used as an additive. The modification of AN grafted films with hydroxyl amine hydrochloride was done for the preparation of amidoxime adsorbent. The constructed adsorbent was characterized using FTIR, DMA and SEM. The amidoxime adsorbent was used for adsorption of Cu(II), Pb(II) and Cr(VI). Adsorption capacity was investigated under different conditions: contact time, pH and initial metal ion concentration. The optimum condition for maximum adsorption was found to be contact time 72 h and initial metal concentration 500 ppm for all the metal ions studied and pH 5.2 for Cu(II), 5.4 for Pb(II), 1.5 for Cr(VI). Kinetic adsorption data was elucidated using pseudo-first-order and pseudo-second-order equations. The equilibrium experimental data of metal adsorption matched Langmuir isotherm model. From the Langmuir equation, the monolayer saturation adsorption capacity (highest adsorption capacity) of the adsorbent was found to be 74.62 mg/g for Cu(II), 107 mg/g for Pb(II) and 156.25 mg/g for Cr(VI). The thermodynamics of metal adsorption was also investigated. Furthermore, desorption and reuse of the adsorbent film was studied. The results suggest that the adsorbent can be effective for adsorption of Cu(II), Pb(II) and Cr(VI).

Data on the removal of heavy metals from aqueous solution by adsorption using melanin nanopigment obtained from marine source: Pseudomonas stutzeri

Heavy metals are one of deadly contaminants in ground water across the globe. Thus, herein, this data set comprises experimental and modelled data on the removal of heavy metals from ground water using melanin synthesized by the marine bacteria Pseudomonas stutzeri. Characterization of biosynthesized melanin and modelling of the kinetic and the thermodynamic study on adsorption of heavy metals such as mercury (Hg(II)), lead (Pb(II)), chromium (Cr(VI)), and copper (Cu(II)) are included in this article. Apart from the study of parameters involved in adsorption such as pH, temperature, concentration and time; the data from these studies are modelled to analyze the nature and characteristic of heavy metals adsorbing to melanin nanoparticles. The figures from models, results from models as tables, characterization and analytical figures are depicted in this work.

Pb(II) adsorption by a novel activated carbon - alginate composite material. A kinetic and equilibrium study

The adsorption capacity of an activated carbon - calcium alginate composite material (ACAA-Ca) has been tested with the aim of developing a new and more efficient adsorbent material to remove Pb(II) ion from aqueous solution. The study was carried out at pH=5, in NaCl medium and in the ionic strength range 0.1-0.75molL^-1. Differential Pulse Anodic Stripping Voltammetry (DP-ASV) technique was used to check the amount of Pb(II) ion removed during kinetic and equilibrium experiments. Different kinetic (pseudo first order, pseudo second order and Vermuelen) and equilibrium (Langmuir and Freundlich) models were used to fit experimental data, and were statistically compared. Calcium alginate (AA-Ca) improves the adsorption capacity (q_m) of active carbon (AC) in the ACAA-Ca adsorbent material (e.g., q_m=15.7 and 10.5mgg^-1 at I=0.25molL^-1, for ACAA-Ca and AC, respectively). SEM-EDX and thermogravimetric (TGA) measurements were carried out in order to characterize the composite material. The results of the speciation study on the Pb(II) solution and of the characterization of the ACAA-Ca and of the pristine AA-Ca and AC were evaluated in order to explain the specific contribution of AC and AA-Ca to the adsorption of the metal ion.