The continuously increasing demand for the commodities produced by chemical industries has triggered heavy metals accumulation in the eco system. . Contamination of aquatic media by heavy metals is a serious environmental problem , . Copper ions are mainly found in wastewaters of industries such as metal cleaning, plating baths, refineries, paper and pulp , fertilizers, tanneries, and wood preservatives. High concentration of copper causes enzyme inhibition leading to Wilson's diseases. It was estimated that the annual industrial discharges of copper into fresh water environments was 1.4 × 10 10 g/year, and the amount of copper in industrial wastes and sewage sludge that have been dumped into the ocean was 1.7 × 10 10 g/year worldwide . The world health organization (WHO) recommended a maximum acceptable concentration of copper in drinking water to be 1.5mg/l . Conventional metal removal techniques such as reverse osmosis, solvent extraction, lime coagulation and ion exchange methods ,  are encountered with certain major disadvantages such as high energy requirements, incomplete removal and generation of large quantity of toxic waste sludge due to various reagents used in a series of treatments. Adsorption techniques are proved to be an effective and attractive process for removal of non-biodegradable pollutants , 
The development of many branches of industries and use of modern technologies, that are accompanied by tougher for environmental protection and search for possibly cheap and most effective adsorption materials. The industrial wastewater usually contains a variety of organic compound and toxic substances which are harmful to fish and other aquatic life. Color is the first contaminant to be recognized in wastewater (Banat et al., 1996), Synthetic dyes are extensively used in paper, textile, food, and pharmaceutical industries. About 40,000–50,000 tons of dyes are continuously entering the water systems due to improper processing and dying methods from industries (Filipkowska et al., 2002).
In this study, neem bark powder (NBP) was tested and evaluated as a possible adsorbent for removal of copper from aqueous solution using batch sorption mode. The maximum removal was found at pH 6.0. Equilibrium data fitted very well in the Dubinin- Radushkevich isotherm model, indicating that adsorption of copper onto NBP seems to be physisorption. The adsorptionkinetics followed pseudo-second-order kinetic model with a good correlation. Intra-particle diffusion was not the sole rate controlling factor.
The adsorption of Zn (II) ions on Carica papaya was studied. The effect of pH, biomass dosage, temperature, adsorptionequilibrium and kinetics, were investigated. The optimum pH for the removal of Zn(II) was found to be 6.0. The Freundlich, Langmuir and Dubinin–Radushkevich (D–R) models were used for the mathematical description of the adsorptionequilibrium of which the Freundlich and D-R fitted very well to the experimental data. The adsorptionkinetics was well described by the pseudo-second order equation. The thermodynamic studies and sorption energy calculation using D-R isotherm model indicated that the adsorption processes were exothermic and physical in nature.
intra-particle diffusion and c is the intercept which gives information about the thickness of the boundary layers i.e, boundary effect increases with increase in the intercept. Mangifera indica adsorption obeys intraparticle diffusion pattern as evident by straight line passing through the origin (Figure not shown) which also indicated an enhancement in the rate of adsorption. Initial portions of the linear segments also revealed that linear effect was due to external mass transfer and remaining linear portion was due to intraparticle diffusion; k p values illustrated a
The experimental data were described by Langmuir, Freundlich and Temkin isotherms. Due to the linear correlation coefficient, the experiment data of dye adsorption onto green perlite and shrimp shell were better fitted by Langmuir than Freundlich and Temkin isotherms as in Table I. The results indicated the homogeneous nature by the monolayer coverage on surface between sorbed molecule and the maximum adsorption capacity valued 14.085 mg/g for green perlite and 5.621 mg/g for shrimp shell. Similar observation was reported by adsorption of anionic dyes onto natural untreated clay . The effect of Langmuir isotherm shape could be used to predict whether adsorption system favorable or unfavorable. The separation factor (R L ) of
The positive value of entropy change indicates the increased randomness at the solid-solution interface during the adsorption of europium on adsorbents. The positive entropy favors complexation and stability of adsorption. The negative values for the Gibbs free energy change show that the adsorption process is thermodynamically feasible and the degree of spontaneity of the reaction increases with increasing temperature as seen in Table II. This is indicating that the adsorption reaction is spontaneous and more favorable at higher temperature. The obtained negative standard Gibbs energy changes indicate that the adsorption reactions are greatly driven towards the products. The increase in adsorption with temperature may be attributed to either increase in the number of active surface sites available for adsorption on the adsorbents or the desolvation of the sorbing species. The decrease in the thickness of the boundary layer surrounding the adsorbent with temperature, so that the mass transfer resistance of adsorbate in the boundary layer decreases -.
Stock solution of the desired dye was prepared with a concentration of 1000 mg/L. Concentrations of 5, 10, 25, 50, 75, and 100 mg/L of the stock solution were developed for plotting the standard curve. To determine the unknown concentrations of dye, this curve was employed. In fact, all the experiments were carried out in 200mL beakers. The sample volume was 100 mL and its concentration was 25 mg/L. The factors influencing the adsorption process included pH (3, 5, 7, 9, 11, and 13), contact time (30, 60, 90, 120, 150, and 180 min), initial concentration of the dye (5, 10, 25, 50, 75, and 100 mg/L), the amount of the sorbent (1, 2, 3, 4, 5, and 6 g), and the temperature (5, 10, 15, 25, and 35°C). During the reaction, the contents of the container were stirred using a magnetic stirrer at around 600 rpm. Once the reaction was finished, it was then centrifuged for 10 min at 3000 rpm. Thereafter, the concentration of the remaining dye was measured using a spectrophotometer of the wavelength of 518 nm. To ensure the correctness of the results, all the experiments were replicated three times, whereby the mean score of the obtained values was calculated. On the whole, 90experimentswere investigated.
The initial pH of the heavy metal is very important factor in any adsorption process . As shown in Fig. 1, there is too less removal of lead ion from aqueous solution at initial pH lower than 2.9 may be due to high concentration of H+ ion. There is a gradual increase of adsorption capacity with increase initial pH. The maximum adsorption capacity was observed at initial pH 4. At pH higher than 4, lead ions may be precipitated and adsorptionstudies could not be performed.
Adsorptionkinetics describes the solute retrieval rate by the adsorbent during the adsorption time. This parameter is important because it determines the efficiency of the adsorption process. Effect of contact times on the adsorption capacity can be seen in Fig. 1. In the Fig.1, it can be seen that the adsorption capacity of the adsorbent was increased with the increasing contact time and in 75 min equilibrium was occurred. The time needed for equilibrium depends on the types and the interaction of the adsorbate and the adsorbent.
increase in adsorption capacity (Malkoc and Nuhoglu, 2005), decrease in adsorption capacity (Akpomie et al., 2013) and irregular behavior (Adekola et al., 2014). In this study the effect of temperature on the adsorption process was investigated in the range of 303 – 343K and the results shown in Fig. 5. It was observed that there was gradual decrease in the percentage removal of Cd(II) ions as the temperature increases from 303-343K implying that the process is exothermic. The decrease in the amount of metal ions adsorbed as temperature increased might be attributed to the fact that high temperature causes rupture in the active binding sites of the adsorbent. This reduces the adsorptive forces between the metal ions and the binding sites resulting in a lower adsorption capacity.
Due to large active surface and chemical structure, activated carbons are one of the most used commercial adsorbents for removal of various pollutants from drinking water and waste water . Various base materials were used for production of activated carbons and numerous studies reported successful fluoride removal with activated carbon obtained from fruit pits, lignin, nut shells, bones, wood, charcoal, coals, lignite and peat .
parameters such as sorbent dosage, contact time, pH, DOC concentration and temperature. The equilibrium data were analyzed by using Freundlich, Langmui, Tempkin and D- R isotherm models and the results are well fitted to D-R and Freundlich equations. It was found that the equilibrium was reached within 150 and 90 min. for (SBTL) and (PP) wastes respectively, also it was found that the optimum pH value of the DOC adsorption was 6. The kinetic studies follow the pseudo-second-order model, effect of temperature on adsorption process shows that adsorption is an exothermic, non-spontaneous and the mechanism is physisorption because of low activation energy. The present work concludes that (SBTL) and (PP) agricultural wastes are effective adsorbents in removing DOC from aqueous solutions.
From previous kineticsstudies  , we examined the evolution of divalent-cation concentration in water in interaction with the adsorbent “brick” and determined the quantity of cation adsorbed onto the brick surface with time (as obtained for Pb(II) adsorption and shown in Figure 3(a)). When the equilibrium state of this kinetic reaction was attained, the dicationic metal (Me 2+ ) adsorbed on brick was in equilibrium with a residual Me 2+ content in the liquid phase. The K D ratio was defined as the distribution coefficient of the solute between the
Abstract-- Hamburger seed shell was activated and used as an alternative adsorbent for removing MB dye from aqueous solution. The kinetics study showed that MB dye adsorption followed the pseudo-second order kinetic model. Isotherm data fitted well to the Freundlich model in the pH and temperature ranges studied. The adsorption capacity was found to increase with temperature, which showed endothermic nature of MB dye adsorption. The negative value of the Gibb’s free energy confirmed the feasibility and spontaneity of the adsorption process. The magnitude of the enthalpy and Gibb’s free energy suggest that the MB dye adsorption occurred by both physical and weak chemical interaction.
The lead ions uptake is greatly affected by the pH of the solution. The amount of Pb(II) adsorbed at different pH values is shown in “Fig. 1”. The amount of Pb(II) adsorbed on RCC was found to increases from 13.2 % to 97.6 % by increasing pH from 1 to 4 and then decrease slightly. At pH 1 there is competition between H + ions and Pb(II) ions for binding sites of adsorbent, therefore the adsorption of Pb(II) ions was least (13.2%). When the initial pH of the solution increases to 2 the adsorption percentage increases to 21.5%, possibly due to little less competition of Pb(II) ions and H + ions. However, when initial pH raised to 4 the adsorption of Pb(II) increased up to maximum of 96.7 % and will remain almost same when the initial pH adjusted to 6 as a result of maximum adsorption of Pb 2+ ions along with H + ions. Further increase in pH of the solution to 8 and 10 results slightly decrease in the adsorption of Pb(II) ions to 95.1 and 94.1 %, respectively.
25. Ayawei, N., Ekubo, A. T., Wankasi, D., and Dikio, E. D. “Synthesis and Application of Layered Double Hydroxide for the removal of Copper in Wastewater”. International Journal of Chemistry. 2015.,. 7., 1; 122 - 132. 26. a) Arivoli S, Venkatraman B R, Rajachandrasekar T and Hema M, Adsorption of ferrous ion from aqueous solution by low cost activated carbon obtained from natural plant material, Res J Chem Environ. 2007.,17, 70-78. b)
The contamination of soil and water by heavy metals continues around the world to present a serious threat to the environment and human health . The development of innovative technologies for cleaning metal remains a challenge because the current processes have many limitations, such as being expensive, disruptive, and only effective in certain concentrations. Polymers and copolymers contain amino or carboxyl groups that could use for coordinating of heavy metals are studied in literature . The polymers provide an excellent material for chelation of metals with high molecular weight and repetitive functional groups . Heavy metals such as copper, lead and cadmium are environmental concerns because of the widespread use and toxicity to human and wildlife [4-5]. Although a greater understanding of the extent of their toxicity and cycling environment is slowly being made. Native starch granules are insoluble in water containing two major polymers: amylose which is essentially a linear polymer of α - (4.1-bound D-glucopyranosyl) units, with little α - (1-6) linkages having a number average degree of polymerization (DP n ) of 800 to 900, and which is composed of branched chains of amylopectin α -(1,4-linked D-
Batch adsorptionstudies: Adsorption experiment was conducted by adding a mass (in g) of activated carbon into 100 ml dye solution of a known concentration (in mg/L) in a 250 ml beaker at a ambient temperature (of around 30 0 C), and the mixture was stirred on a magnetic stirrer at 100 rpm. The samples were withdrawn from stirring setup at set time intervals, and the adsorbent was separated from the solution by the help of a micropipette, and then allowed to settle for 10 minutes. The absorbance of the supernatant solution was estimated to determine the residual dye concentration, and was measured before and after treatment with double beam spectrophotometer at the maximum wavelength of 500 nm. The above described method was repeated in a batch adsorption process, it was carried out to investigate the effects of variables such as; initial dye concentration (10–60) mg/L, contact time (20–180) minutes, pH (3–11) adjusted using 0.1M NaOH and 0.1M HCl solution and a pH meter. The effects of temperature and carbon dosage were also evaluated at 303, 313 and 323 K, and between the ranges of 0.5 g – 2.5 g respectively.
Most of the commercially used dyes are resistant to biodegradation and photo-degradation and even oxidizing agents. Unless and otherwise properly treated, these dyes can significantly affect photosynthetic activity in aquatic life due to reduced light penetration and may also be toxic to certain forms of aquatic life due to the presence of metals and chlorides in them. Considerable work has been carried out on the removal of dye from wastewater [2-6] aerobic granules , rice husks , pineapple stem waste , cedar sawdust and crushed brick , nitric-acid treated water hyacinth , yellow passion fruit peel  are used in the treatment of textile wastewater. Many physical and chemical treatment methods including adsorption, coagulation, precipitation, filtration, electrodialysis, membrane separation and oxidation have been used for the treatment of dye containing effluents. Further, the adsorption process provides an attractive alternative treatment, especially if the adsorbent is inexpensive and readily available.