Rifaqat Ali Khan Rao

ADSORPTION STUDIES ON RICE HUSK: REMOVAL AND RECOVERY OF CD (II) FROM WASTEWATER

Adsorption behaviour of Ni(II), Zn(II), Cd(II) and Cr(VI) on untreated and phosphate-treated rice husk (PRH) showed that adsorption of Ni(II) and Cd(II) was greater when PRH was used as an adsorbent. Sorption of Cd(II) was dependent on contact time, concentration, temperature, adsorbent doses and pH of the solution. The Langmuir constants and thermodynamic parameters have been calculated at different temperatures. It was found that recovery of Cd(II) from synthetic wastewater by column operation was better than a batch process.

Removal and recovery of heavy metals from electroplating wastewater by using Kyanite as an adsorbent

Kyanite, a commercial mineral has been utilized as an adsorbent for the removal of heavy metals, such as Ni(II), Zn(II), Cr(VI) and Cu(II) from electroplating wastewater. The effect of contact time, pH, concentration, adsorbent doses, particle size of the adsorbent, salinity and hardness, both in natural and wastewater on the adsorption of Cu(II) have been studied in detail. The adsorption of metal ions seems to be an ion exchange process. The adsorbed metals ions from electroplating wastewater were recovered by batch as well as column operation using dilute HCl solution. The column operation was found to be more effective compared to batch process.

Adsorption studies on fruits of Gular (Ficus glomerata): Removal of Cr(VI) from synthetic wastewater

The adsorption of Cr(VI) was studied in batch system using fruits of Ficus glomerata as adsorbent. The effect of temperature, pH, initial Cr(VI) concentration and time was investigated. Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) was used to investigate surface morphology and active functional groups present on the adsorbent surface. Thermodynamic parameters like free energy change (DeltaG(0)), enthalpy (DeltaH(0)) and entropy (DeltaS(0)) indicate the spontaneous, endothermic and increased randomness nature of Cr(VI) adsorption. Equilibrium data were fitted well with Langmuir isotherm at 50 degrees C. The magnitude of mean free energy indicates chemical nature of adsorption. The breakthrough and exhaustive capacities were found to be 5 and 23.1 mg g(-1) respectively. The applicability of the adsorbent has been demonstrated by removing Cr(VI) from electroplating wastewater.

Removal of Cr(VI) from electroplating wastewater using fruit peel of Leechi (Litchi chinensis)

Abstract Fruit peel of Litchi chinensis showed remarkable adsorption capacity towards Cr(VI) ions. The effect of temperature, pH, initial Cr(VI) concentration and time was investigated using batch process. The adsorption of Cr(VI) was maximum at pH 2. Fourier transform infrared spectroscopy (FTIR) was used to explore number and position of active functional groups available for the binding of Cr(VI) ions. Thermodynamic parameters like change in standard free energy (ΔG °), enthalpy (ΔH °) and entropy (ΔS °) indicated the spontaneous, endothermic and increased randomness nature of Cr(VI) adsorption. Equilibrium data were well fitted in Langmuir isotherm at 40°C.The value of mean free energy (E = 8.28 kJ mol−1) indicated that adsorption process was chemical in nature. The breakthrough and exhaustive capacities were found to be 30 and 50 mg g−1 respectively. The results indicated that the adsorbent could be used effectively for the removal of Cr(VI) from electroplating wastewater by batch process.

Utilization of carbon derived from mustard oil cake (CMOC) for the removal of bivalent metal ions: Effect of anionic surfactant on the removal and recovery

Effect of sodium dodecyl sulfate (SDS) on the adsorption of Zn(II) and Ni(II) on CMOC was investigated. Addition of SDS favored the adsorption process. Adsorption process was found to be dependent on concentration, pH, dose, contact time and temperature. Thermodynamic studies showed that the process is endothermic and spontaneous. The spontaneity increases with increase in temperature. D-R isotherm suggests that the adsorption is chemical in nature. Kinetics studies showed better applicability of pseudo second order model. Reichenberg equation showed that pore diffusion was not only the rate determining step but some other process like film diffusion was also involved in the adsorption. These metals could be desorbed (75-80%) with 0.1M HCl as eluent.

Adsorption studies of Dichloromethane on some commercially available GACs: Effect of kinetics, thermodynamics and competitive ions

The objective of this work was to compare the effectiveness of four commercially available granular activated carbons (GACs); coconut (CGAC), wood (WGAC), lignite (LGAC) and bituminous (BGAC) for the removal of dichloromethane (DCM) from aqueous solution by batch process. Various parameters such as thermodynamics, kinetics, pH, concentration of adsorbate, dosages of adsorbent and competitive ions effect on DCM adsorption were investigated. Maximum adsorption capacity (45.5mg/g for CGAC) was observed at pH 6.0-8.0. The kinetics data indicate better applicability of pseudo-second-order kinetics model at 25 and 35 degrees C. Freundlich model was better obeyed on CGAC, WGAC, and BGAC, while LGAC followed Langmuir model. The adsorption process for 100mg/L initial DCM concentration on CGAC was exothermic in nature. The adsorption of DCM on various adsorbents involves physical adsorption process. The adsorption of DCM over a large range of initial concentration on CGAC and LGAC is effective even in presence of ionic salts.

Adsorption studies and the removal of dissolved metals using pyrolusite as adsorbent

The adsorption of metals from aqueous solutions of Pb2+, Zn2+ and Mg2+ on naturally occurring pyrolusite have been studied. The chemical stability of the pyrolusite has been determined in NaOH, H2SO4, HNO3, HCl, NaCl and NK4Cl solutions of various concentrations. Adsorption of the metal ions followed the order Pb2+>Zn2+>Cd2+.The maximum adsorption of Pb2+ (100%) occurred at pH 7. the relation between the amount of Pb2+ adsorbed per unit weight of pyrolusite and the concentration of Pb2+ at equilibrium follows the Freundlich adsorption isotherm.The efficiency of pyrolusite has been demonstrated by removing lead from synthetic waste water. 100% and 96% removal of lead have been achieved from synthetic waste water containing 5 mg l−1 and 120 mg l−1 of Pb2+ respectively at pH 7. The results of these studies suggest that pyrolusite might provide an economical method for the removal of lead from industrial waste water.

Batch and Column Studies for the Removal of Lead(II) Ions from Aqueous Solution onto Lignite

The effectiveness of lignite for the removal of Pb(II) ions from aqueous solution has been evaluated. The maximum adsorption of Pb(II) ions onto lignite was 98%. The adsorption depends on the initial concentration of Pb(II) ions, the pH, the adsorbent dosage, the temperature and the contact time. Kinetic studies showed that the pseudo-second-order kinetic model provided the best fit to the experimental data. The adsorption process was found to be endothermic and spontaneous. The mean free energy values indicated that adsorption occurred via a chemisorption process. Both the Langmuir and Freundlich models provided good fits to the experimental data obtained at 40 °C, as indicated by the χ2-test. The breakthrough and exhaustive capacities were found to be 5 mg/g and 35 mg/g, respectively. The percentage recovery of adsorbed Pb(II) ions by column methods was ca. 80% when 0.1 M HCl was used as the eluent.

Adsorption Properties of Coriander Seed Powder (Coriandrum sativum): Extraction and Pre-concentration of Pb(II), Cu(II) and Zn(II) Ions from Aqueous Solution

Coriander seed powder has been shown to exhibit a remarkable adsorption potential towards Pb(II), Cu(II) and Zn(II) ions from aqueous solution, with the adsorption capacities following the order Pb(II) > Cu(II) > Zn(II). The influences of pH, initial metal ion concentration, adsorbent dosage and contact time on the process were investigated. The adsorption data at different temperatures were well fitted by the Langmuir, Freundlich, Temkin and Dubinin–Radushkevich (D–R) model isotherms. The kinetic data obeyed the pseudo-second-order kinetic model. The thermodynamic parameters showed that the adsorption of Pb(II) ions was endothermic and spontaneous. Competitive adsorption in the Pb(II)–Cu(II) and Pb(II)–Zn(II) systems was also studied. The breakthrough capacities of Pb(II), Cu(II) and Zn(II) ions in single metal ion systems were higher than in multi-metal ion systems. The analytical application of the adsorption process was demonstrated by the removal of Pb(II) ions from the wastewater derive from the manufacture of lead acid batteries. Excellent results were obtained when desorption of the studied metal ion from very dilute solution was effected by column methods. Hence, these methods were further utilized for the extraction and pre-concentration of Pb(II), Cu(II) and Zn(II) ions from very dilute synthetic mixtures of these metal ions prepared in doubly distilled water as well as in tap water to enable their subsequent determination by atomic absorption spectrometry.

Adsorption Studies of Heavy Metals on Tectona Grandis: Removal and Recovery of Zn (II) from Electroplating Wastes

Teak leaves (Tectona grandis), an inexpensive material has been utilized as an adsorbent for the removal of Zn (II) from aqueous solutions as well as from industrial waste. The effects of contact time, pH, concentration, temperature and adsorbent dosage on the removal of Zn (II) have been studied. The percent removal of different metals on teak leaves has been found in the order: Zn (II) > Cd (II) > Ni (II) > Cr (VI). Thermodynamic parameters like free energy, entropy and enthalpy changes for the adsorption of Zn (II) have been computed and discussed. The kinetics and the factor controlling the adsorption process have also been studied. The analytical application has been demonstrated by removing Zn (II) from electroplating waste water using batch as well as column operations. The recovery by column operation was found to be higher (96%) than that by batch process (76%).