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Presence of BTEX compounds in water is a global concern. The effectiveness of HDTMA and TMPA cations intercalated Bentonite, corresponding to 100% of CEC in the removal of Benzene, Toluene, Ethylbenzene and Xylene (BTEX) in aqueous solution was assessed. Batch experiments were conducted to determine the influences of contact time and adsorbate concentration on the adsorption efficiency. FTIR spectroscopy, SEM and XRD were used to determine the adsorbent properties. Results showed that surfactant modification of the adsorbent led to structural changes and fractional attainment to equilibrium showed that equilibrium was reached after 120mins. The sorption of BTEX by Bt-HDTMA and Bt-TMPA were in the order of B

Aims: To compare the efficiency of Sorghum Hull of two different particle sizes, different concentrations modified with mercaptoacetic acid and the effect of each on the heavy metal removal to obtain optimum conditions for sorption process. Study Design: The concentrations of the metal ions were monitored using Atomic Absorption Spectrophotometer (AAS). Place and Duration of Study: This study was carried out at the Industrial Chemistry laboratory, Department of Pure and Industrial Chemistry, University of Port Harcourt between February and August 2013. Original Research Article Imaga et al.; IRJPAC, 5(4): 318-330, 2015; Article no.IRJPAC.2015.025 319 Methodology: The Sorghum Hulls (SH) (Sorghum bicolor) obtained from a Brewery, were washed and air dried, crushed to smaller particles and sieved to obtain particle sizes of 106 μm and 250 μm. They were activated by soaking in excess of 0.3M HNO3 solution for 24 h, filtered through a Whatman No.41 filter paper, rinsed with deionised water and air dried for 24 h. The air-dried activated sorghum hulls were divided into three parts, one part was left unmodified and the other two parts were modified by 0.5M and 1.0M mercaptoacetic acid (HSCH2COOH). Equilibrium sorption of Ni (II), Cu (II) and Zn (II) were carried out for each adsorbent (106 μm and 250 μm) at pH of 6.0 and temperature of 28°C to find the effects of initial concentration on the sorption process by preparing stock solutions of 1000 mg/L of Cu (II), Ni (II) and Zn (II) ions from CuSO4, Ni(C2H3O2)2, and ZnSO4 respectively. Working concentrations of 10, 20,30,40,50 mg/L were obtained by serial dilutions. The concentrations of these solutions were confirmed using Atomic Absorption Spectrophotometer (AAS). The difference in the metal ion concentration of the solutions before and after sorption gave the amount adsorbed by each adsorbent. Results: Sorption efficiency followed the trend Cu 2+ >Ni 2+ >Zn 2+ and Ni 2+ >Cu 2+ >Zn 2+ for 106μm and 250μm, respectively. This was influenced by factors such as ionic radii, ionic charge, hydration energy, initial metal ion concentration, contact time, adsorbate pH and extent of acid modification. Sorption capacity followed the sequence: 1.0MSH>0.5MSH>USH. Equilibrium sorption of the three metals on the adsorbents using coefficient of determination (R) showed that sorption of Zn on 250μm size and sorption of Ni 2+ on 106μm size followed Langmuir isotherm; sorption of Zn 2+ on 106μm mesh and sorption of Cu on 250μm size by Freundlich isotherm and sorption of Cu on 106μm size and sorption of Ni 2+ on 250μm mesh by Temkin isotherm. Sorption on 1.0MSH gave the highest value of constants: (qmax = 121.814 mg/l, KF = 1.5281 mg/l and bT = 0.245 kJ/mol) and (qmax = 148.932 mg/l, KF = 1.7246 mg/l and bT = 0.262 kJ/mol) for 106 μm and 250 μm size, respectively, for Langmuir, Freundlich and Temkin isotherms respectively. Conclusion: Therefore, Sorghum Hulls were found to be good adsorbent for Ni, Cu and Zn ions with mercaptoacetic acid modification increasing the sorption capacity.

Palm oil is one of the two most important vegetable oils in the world's oil and fats market. The extraction and purification processes generate different kinds of waste generally known as palm oil mill effluent (POME). Earlier studies had indicated the possibility of using boiler fly ash to adsorb impurities and colour in POME treatment. The adsorption treatment of POME using boiler fly ash was further investigated in detail in this work with regards to the reduction of BOD, colour and TSS from palm oil mill effluent. The amount of BOD, colour and TSS adsorbed increased as the weight of the boiler fly ash used was increased. Also, the smaller particle size of 425µm adsorbed more than the 850µm size. Attempts were made to fit the experimental data with the Freundlich, Langmuir and Dubinin-Radushkevich isotherms. The R² values, which ranged from 0.8974-0.9898, 0.8848-0.9824 and 0.6235-0.9101 for Freundlich, Langmuir and Dubinin-Radushkevich isotherms respectively, showed that Freundlich isotherm gave a better fit followed by Langmuir and then Dubinin-Radushkevich isotherm. The sorption trend could be put as BOD > Colour > TSS. The apparent energy of adsorption was found to be 1.25, 0.58 and 0.97 (KJ/mol) for BOD, colour and TSS respectively, showing that sorption process occurs by physiosorption. Therefore, boiler fly ash is capable of reducing BOD, Colour and TSS from POME and hence could be used to develop a good adsorbent for POME treatment.

The potentials of cocoa pod husk to adsorb Cu (II), Cd (II), Pb (II) and Fe (II) ions from aqueous solutions was investigated in a batch system. The effects of contact time, initial metal ion concentration and adsorbent dose on the adsorption capacity of the adsorbent were examined. The percent adsorbed increased as initial metal ion concentration, contact time and adsorbent dose was increased until equilibrium was reached. Langmuir isotherm and pseudo-second order models were used to analyse the equilibrium and kinetic experimental data respectively. Equilibrium experimental data of Cu (II), Cd (II), Pb (II) and Fe (II) adsorption onto cocoa pod fitted well to Langmuir model and the kinetic data also fitted well to the pseudo-second order model, as indicated by the correlation coefficients. The maximum sorption capacity (qmax) ranged as 4.16, 4.42, 4.69 and 4.83 mg/g for Fe (II), Cd (II), Cu (II) and Pb (II) respectively. This study demonstrated that the waste cocoa pod could be used as a potential adsorbent for toxic metals such as Cu (II), Cd (II), Pb (II) and Fe (II). Keywords : Adsorption isotherm, Adsorption Kinetic, Cocoa pod, Langmuir isotherm, Pseudo-second order model

The desorption of Ni2+ from three oil palm fruit fibre adsorbents (UOPF, 0.5MOPF and 1.0MOPF) using five desorbing solutions showed a desorption efficiency following the trend, 0.1M HCl > 0.1MH2SO4 > 0.1MHNO3 > 0.1MNaOH >hot deionized H2O. The Elovich desorption constant, β values for the 0.1MHCl desorbent were: 6.45 X10-1, 5.57 x 10-1 and 4.34 x 10-1g. mg-.min-1 for UOPF,0.5MOPF and 1.0MOPF adsorbents respectively. The surface residence time ح values for the 0.1MHCl desorbent were; 32.3, 28.6 and 26.8 seconds for UOPF, 0.5MOPF and 1.0MOPF adsorbents respectively. Kinetic modeling analysis of the Elovich and pseudo-first order desorption equations, indicates that the latter model described the desorption of Ni2+ better.Keywords: Nickel, desorption, modeling, kinetics, Elovich, oil palmJournal of Applied Science, Engineering and Technology, Volume 8, 2008

The need to clean-up heavy metal contaminated environment can not be over emphasized. This paper describes the adsorption isotherm studies of Cd (II), Pb (II) and Zn (II) ions from aqueous solution using unmodified and EDTA-modified maize cob. Maize cob was found to be an excellent adsorbent for the removal of these metal ions. The amount of metal ions adsorbed increased as the ini- tial concentration increased. Also, EDTA - modification enhanced the adsorption capacity of maize cob probably due to the chelating ability of EDTA. Among the three adsorption isotherm tested, Dubinin- Radushkevich gave the best fit with R2 value ranging from 0.9539 to 0.9973 and an average value of 0.9819. This is followed by Freundlich isotherm (Ave. 0.9783) and then the Langmuir isotherm (Ave. 0.7637). The sorption process was found to be a physiosorption process as seen from the apparent ener- gy of adsorption which ranged from 2.05KJ\mol to 4.56KJ\mol. Therefore, this study demonstrates that maize cob which is an environmental pollutant could be used to adsorb heavy metals and achieve cleanliness thereby abating environmental nuisance caused by the maize cob.

The pollution and toxicity problems posed by arsenic in the environment have long been established. Hence, the removal and recovery remedies have been sought, bearing in mind the effi- ciency, cost effectiveness and environmental friendliness of the methods employed. The sorption kinet- ics and intraparticulate diffusivity of As (III) bioremediation from aqueous solution using modified and unmodified coconut fiber was investigated. The amount adsorbed increased as time increased, reach- ing equilibrium at about 60 minutes. The kinetic studies showed that the sorption rates could be described by both pseudo-first order and pseudo-second order process with the later showing a better fit with a value of rate constant of 1.16 x 10 -4 min-1 for the three adsorbent types. The mechanism of sorption was found to be particle diffusion controlled. The diffusion and boundary layer effects were also investigation. Therefore, the results show that coconut fiber, both modified and unmodified is an efficient sorbent for the removal of As (III) from industrial effluents with particle diffusion as the pre- dominant mechanism.

The use of unmodified and carboxymethylated granular activated carbon (GAC) for adsorption of Hg2+ and Ni2+ from aqueous solutions was assessed in this work. The effect of concentration and modification by carboxymethyl group on the adsorption of these metal ions was studied in batch process. The adsorption data were correlated with Langmuir, Freundlich, Dubinin-Radushkevich and Temkin isotherm models. Results show that Freundlich model gave the best description for the adsorption process followed by the Langmuir model. Langmuir adsorption capacity corresponding to sites saturation was found to be 20.83 mg g-1 and 19.05 mg g-1 for adsorption of the Hg2+ and Ni2+ respectively onto the unmodified adsorbent and 19.72 mg g-1 and 17.01 mg g-1 for adsorption onto the carboxymethylated substrate. The apparent energy values obtained from the Dubinin-Radushvich model further indicates that the forces of the adsorption follow physical mode. Modification by carboxymethyl group generally caused a decline in the adsorption capacity by the adsorbent. Results obtained generally showed that Hg (II) ions were better adsorbed onto both adsorbents as compared to Nickel (II).