Initial Concentration Of Cu Research Articles

Reduksi Ion Cu(II) Menggunakan Karbon Aktif dari Sekam Padi Teraktivasi Fisika dan Kimia

This research proposed a method to produce activated carbon from rice husk by carbonation process, physical activation and chemical activation using NaOH. The performance of activated carbon was tested by batch experiments in which the adsorption system contained 1 g of rice husk activated carbon in 100 mL of artificial wastewater with initial concentration of Cu(II) ion being 148.26 mg/L, initial pH 6, at 27 oC and 1 atm to determine the efficiency of reducing Cu(II) ion over the contact time and presence of stirring on chemical activation. The results showed that the efficiency of reducing Cu(II) ion by rice husk activated carbon increased exponentially with increasing contact time with a maximum value of 74.33% at 90 minutes of contact time. The results also showed that stirring on chemical activation increased the efficiency of Cu(II) ion reduction by 14.94%. Adsorption kinetics studies showed that Cu(II) ion reduction followed the pseudo-second order adsorption equation with the adsorption capacity of 10.18 mg/g and adsorption rate constant of 0.0013 g/mg.min for rice husk activated carbon without stirring in the chemical activation. Stirring in the chemical activation.increased the capacity and rate of adsorption constant to 12.07 mg/g and 0.0052 g/mg.min, respectively.

Kinetic and isotherm investigation into the removal of heavy metals using a fungal-extract-based bio-nanosorbent

Abstract Adsorption is very economical and environmentally friendly method that is commonly accepted as a promising technique for the removal of heavy metals. In this study a fungal-extract-based (FE-CB) bio-nanosorbent was prepared and used as an efficient biosorbent for the removal of heavy metals, namely Cu(II) and Ni(II), from aqueous solutions. FE-CB was characterized by scanning electron microscope, Brunauer–Emmett–Teller surface area and porosity analyzer, Fourier transform infrared, x-ray diffraction, differential scanning calorimeter, thermalgravimetric analysis and zeta potential. The Brunauer–Emmett–Teller surface area, pore volume and average pore diameter of FE-CB were 7.43 m2/g, 0.060 cm3/g, and 2.82 nm, respectively. The adsorbtion properties of FE-CB onto both Cu(II) and Ni(II) were investigated in terms of biosorbent dosage, temperature, initial concentration of Cu(II) and Ni(II) ions, pH and contact time in the batch experiments. The dependence of the biosorption mechanism on pH was revealed and the optimum pH was determined as 6 for Ni(II) and 5 for Cu(II). The Langmuir and Freundlich isothermal models and the kinetic Pseudo-first-order and Pseudo-second-order kinetic models were used to describe the adsorption performance of FE-CB. The activation energy was calculated by pseudo-second-order rate constants. In addition, thermodynamic parameters, standard Gibbs free energy, standard enthalpy and standard entropy were analyzed using the (Van’t Hoff equation). The biosorption process was found to be spontaneous, favorable and endothermic.

Absorption of Cu(II) and Zn(II) from Aqueous Solutions onto Biochars Derived from Apple Tree Branches

The aim of this study was to investigate the adsorption of Cu(II) and Zn(II) onto apple tree branches biochar (BC) produced at 300, 400, 500 and 600 °C (BC300, BC400, BC500, and BC600), respectively. The effect of adsorbent dosage, pH value, contact time, initial concentration of Cu(II) or Zn(II), and temperature on the adsorption process were investigated. The result showed that 5 g BC·L−1 was the optimal dosage to remove Cu(II) and Zn(II) from wastewater and the maximum adsorption efficiency was achieved at a pH of 5.0 for all the BCs when the initial concentration of Cu(II) and Zn(II) were 64 and 65 mg L−1, respectively. Adsorption kinetics and isotherm experiments showed that the pseudo-second order equation and the Langmuir isotherm could best describe the adsorption process, indicating that the adsorption of Cu(II) and Zn(II) onto BCs were monolayer processes and chemisorption was the rate limiting step. The values of ΔG0 for the absorption of Cu(II) and Zn(II) on all BCs were negative, while the values of ΔH0 were positive, suggesting that the absorption was a spontaneous endothermic process. The mechanisms of BC adsorption of metal ions adsorption include surface precipitation, ion exchange, and minor contribution by cation-π interaction. BC500 had highest Cu(II) and Zn(II) adsorption capacity under various conditions (except at pH 2.0). The maximum adsorption capacities of Cu(II) and Zn(II) on BC500 were 11.41 and 10.22 mg·g−1, respectively. Therefore, BC derived from apple tree branches produced at 500 °C can be used as an adsorbent to remove Cu(II) and Zn(II) from wastewater.

Adsorption of Copper (II) from Aqueous Solution Using Tea (<i>Camellia sinensis</i>) Leaf Waste

The extensive use of heavy metals such as copper in various industries has discharged a large amount of the metals into the environment which is toxic at higher concentrations. The use of low-cost agricultural waste of biological origin such as tea waste may be an economic solution to this problem. Tea waste is among the potential material to be developed as an adsorbent for heavy metal ions. Tea waste contains cellulose and lignin which have been reported having an excellent metal binding capacity. This study aims to use tea waste for the removal of Cu2+ ions. The effect of variation in different parameters like initial concentration of Cu2+ ions in solution, adsorbent dosage and contact time were investigated using batch adsorption method. The adsorbent, tea waste was characterized using a compound microscope and FTIR spectroscopy. Experimental results showed that the maximum removal of the copper ion by tea waste at optimum condition (pH 7, 60 min. contact time, 0.8 g adsorbent dose and 0.7 M concentration) is 74%. The adsorbent prepared from tea waste is efficient and it can be conveniently employed as a low-cost alternative in the treatment of wastewater for heavy metal removal.

Adsorption of Copper(II) on Dithizone-Immobilized Coal Fly Ash

The adsorption of Cu (II) ions onto selective adsorbent of coal fly ash from Sugar Factory Madukismo, Yogyakarta, Indonesia modified with dithizone has been investigated in batch mode. Some parameters influencing immobilization of dithizone and adsorption of Cu (II) were optimized including an effect of pH, contact time and initial concentration of Cu (II) ions. The FT-IR and XRD analytical results show that the surface of coal fly ash can be modified by immobilization of selective organic ligand towards Cu (II) ions. The optimum conditions for adsorption of Cu (II) are achieved at pH 5, the optimum mass of DICFA and ACFA for copper adsorption were 0.2 g. Kinetics adsorption for copper ions follows pseudo-second-order kinetics with optimum adsorption contact time 60 min for DICFA and ACFA. Isotherms adsorption for Cu ion follow the Langmuir isotherms with chemisorption process and optimum concentration of Cu ion adsorption of 70 mg.L-1 for DICFA and ACFA.

High performance of phytic acid-functionalized spherical poly-phenylglycine particles for removal of heavy metal ions

In the present work, a novel material consisting of phytic acid-functionalized poly-phenylglycine (PA-PPG) was successfully synthesized through radical polymerization and used for the removal of heavy metals ions from water. Microscopic images revealed the formation of homogenous particles in aggregated form. The chemical composition of the PA-PPG was examined using X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) spectroscopy. The influence of various experimental parameters such as solution pH, alkaline metals, and initial concentration of Cu, Pb, Cd ions on the removal efficiency of PA-PPG was assessed by using absorption atomic spectroscopy (AAS). The PA-PPG sample exhibited high maximum adsorption capacity of 90.5, 732.4, and 216 mg/g for Cu, Pb, and Cd ions, respectively. The PA-PPG demonstrated a pH-dependent adsorption with a maximum adsorption capacity achieved at pH 5.2. The Langmuir and Temkin models described well the adsorption isotherm data and a probable adsorption mechanism based on complexation and electrostatic attraction was proposed. Moreover, the developed PA-PPG can be reused for four cycles without any apparent loss of its adsorption capacity. The obtained results prove the efficiency of phytic acid, validate and promote the idea of using an active molecule to enhance the capacity of poly-phenylglycine for environmental remediation.

Magnetite nanoparticles decorated on multi-walled carbon nanotubes for removal of Cu2+ from aqueous solution

ABSTRACT Acid-functionalized multi-walled carbon nanotube (MWCNTs-COOH) was prepared by acid treatment followed by decoration with magnetite (Fe3O4) nanoparticles (Fe3O4/MWCNTs-COOH) by co-precipitation of Fe2+/Fe3+ in the colloidal suspension of MWCNTs-COOH. The adsorption capacity and separation efficiency of these two adsorbents were investigated for the removal of Cu2+ ions in aqueous solution as water treatment adsorbents. The effect of reaction conditions, such as contact time, initial concentration of Cu2+ ions, and adsorbent dosage, on the adsorption capacity of MWCNTs-COOH was investigated. It was found that contact time of 10 min, adsorbent dosage of 0.2 g/L and 15 mg/L as initial concentration of Cu2+ ions are ideal conditions for maximum adsorption capacity (10.45 mg/g). The adsorption capacity of synthesized Fe3O4/MWCNTs-COOH containing different weight percent of Fe3O4 (10, 25, 50 wt%) was explored for removal of Cu2+ ions from aqueous solution and the best results achieved with 25 wt% Fe3O4/MWCNTs-COOH, which exhibited optimum adsorption capacity of 9.50 mg/g and 97% separation efficiency. Further, Langmuir and Freundlich isotherm models were applied to validate experimental data obtained in this work for Cu2+ adsorption.

Removal of Cd(II) and Cu(II) from Aqueous Solution by Na+-Modified Pisha Sandstone

Heavy metals have caused serious environmental issues, which are enriched during open-cast coal mining. It is urgent to develop sustainable remediation materials to protect and restore the contaminated soil and aquifers in mining areas. The feasibility of applying Pisha sandstone (PS) and Na+-modified Pisha sandstone (Na-PS) for adsorption of heavy metals was evaluated. Na-PS exhibited maximum Cd(II) and Cu(II) removal rates of 65.9% and 99.8%, respectively, exceeding the corresponding values for PS (8.2% and 1.3%, respectively) in 1 × 10−3 M solution. Efficient heavy metals adsorption occurred in the pH range 5.0–6.0. The adsorption of Cu(II) and Cd(II) on PS and Na-PS was characterized by kinetic models and adsorption isotherms and was well represented by pseudo-second-order kinetics (R2 > 0.99) and the Langmuir and Freundlich isotherm models. The values of the thermodynamic parameters indicated that the interactions were spontaneous endothermic reactions. Binary solutions adsorption isotherms indicated that the linearity of the adsorption amount and initial concentration of Cu(II) and Cd(II) was better in certain ranges and the adsorbents were selective towards Cu(II) rather than Cd(II). Therefore, PSs can be used as excellent adsorbents for Cu(II) and Cd(II) remediation from contaminated surface water.

Simultaneous heavy metal reduction and voltage generation with synergy membrane-less microbial fuel cell

Metal contaminated wastewater effluent from industries has caused several environmental problems and public health due to its toxicity. Conventional heavy metal reduction processes are neither economical nor environmentally friendly. A synergy economical single chamber up-flow membrane-less microbial fuel cell (UFML-MFC) was fabricated to study the feasibility of heavy metal reduction and voltage generation. Cu (II) was used as electron acceptor to explore the mechanism of metal treatment in UFML-MFC. The performances of the UFML-MFC were investigated with 0 mg/L, 5 mg/L and 10 mg/L concentration of Cu (II) in terms of voltage output, chemical oxygen demand (COD) reduction and Cu (II) reduction efficiency and electrode spacing distance. UFML-MFC used carbon felt as anode and cathode material where anode region was filled with 0.2 cm of gravels at anode region. Overall performance deteriorated with increased initial concentration of Cu (II). Voltage generation decreased from 71 mV to 11.1 mV. COD reduction decreased from 56% to 36%. Moreover, the Cu (II) reduction efficiency was reduced from 87.56% to 36.98%. These results showed that the increased concentration of the Cu (II) could potentially reduce the microbial activities. However, UFML-MFC showed that the shorter distance of electrode spacing (anode and cathode) could enhanced the voltage output. These results showed the great ability of integrating UFML-MFC for heavy metal reduction.

Biosorption of copper(II) onto spent biomass of Gelidiella acerosa (brown marine algae): optimization and kinetic studies

This study exclusively focused on the potential application of an inexpensive and sustainable waste macro-algal biomass as an adsorbent for biosorption of copper ions from aqueous medium. After extraction of agar from brown macro-marine algae Gelidiella acerosa, the residual biomass without any further treatment was used as an adsorbent for the expulsion of copper from wastewater. Physicochemical parameters of biosorption like initial pH, initial concentration of Cu(II) solution and biosorbent dosage were optimized using response surface methodology. The maximum copper biosorption potential of 96.36% was observed at optimum conditions of pH of 5.31, initial concentration of 23.87 mg/l and biosorbent dosage of 0.41 g/l. Adopting FTIR and SEM techniques, the surface morphological features of biosorbent were studied. The pseudo-second-order kinetic model was found to be a proper approach to describe biosorption kinetics. All these results confirmed that spent G. acerosa could be considered as an efficient, eco-friendly and economic alternative for Cu(II) removal from aqueous solution.

Lignin/alginate/hydroxyapatite composite beads for the efficient removal of copper and nickel ions from aqueous solutions

This study was conducted to analyze the adsorption efficiency of lignin/alginate/hydroxyapatite composite beads for the removal of copper Cu(II) and nickel Ni(II) ions from an aqueous solution. For this purpose, lignin, alginate and hydroxyapatite (HAp) composite was prepared in the form of lignin/alginate/hydroxyapatite composite beads. Adsorbents were synthesized in three different ratios by mixing lignin/alginate/hydroxyapatite and sodium alginate in distilled water (25�30 ml) which was then added dropwise to the calcium chloride (CaCl2) solution to form its lignin/alginate/ hydroxyapatite composite beads. Synthesized beads were characterized using X-ray powder diffrac-tion, Fourier transform infrared spectroscopy, scanning electron microscopy, and thermogravimetric analysis. The effect of various experimental parameters such as contact time, pH, the initial concentration of Cu(II) and Ni(II) and adsorbent dose on adsorption capacity was investigated. Kinetic and isotherm data confirmed that the pseudo-first-order model and Langmuir isotherm were best fitted to experimental data. An increase in the adsorption capacity of heavy metals from an aqueous solution was observed with the increase in lignin percentage in beads. The maximum adsorption capacity for Cu(II) and Ni(II) was 79.67 and 71.18 mg/g, respectively for C3 (60) lignin Reusability study of lignin/alginate/hydroxyapatite beads showed 79 removal efficacy after four successive adsorp-tion-desorption cycles. The results showed that lignin/alginate/hydroxyapatite composite beads can be used as promising environmentally benign adsorbent for the removal of heavy metal ions from an aqueous solution. © 2020 Desalination Publications. All rights reserved.

Dendrimer functionalized nanocrystalline cellulose for Cu(II) removal

A series of poly(amidoamine) (PAMAM) dendrimer-functionalized nanocrystalline cellulose (NCC) composites were prepared and characterized by FTIR, XPS, XRD, TGA and TEM as well as elemental analysis. Their performance as adsorbents in Cu(II) removal from water solutions were evaluated. The influence of the initial concentration of Cu(II), pH value, contact time on the adsorption performance was studied. Compared with unmodified NCC, PAMAM functionalized NCCs show significantly higher adsorption capacity. The second generation of PAMAM functionalized NCC (NCC-2.0 PAMAM) shows a Cu(II) adsorption capacity of 92.07 mg/g at 25 °C. The adsorption isotherm of Cu(II) by NCC-2.0 PAMAM follows a Langmuir model and the adsorbent could be regenerated with 0.01 mol/L HCl.

Decomplexation of Cu(II)/Ni(II)-EDTA by ozone-oxidation process.

In this study, ozone-oxidation was used to treat synthetic chemical plating solution containing Cu(II)/Ni(II)-EDTA solution to realize the purpose of decomplexation. The effects of solution pH, initial concentration of Cu(II)/Ni(II)-EDTA, the molar ratio of EDTA to Cu(II)/Ni(II), and the coexistence of Cu(II)/Ni(II) on their removal efficiencies were investigated. The degradation of EDTA-Cu(II) and EDTA-Ni(II) were mainly attributed to OH oxidation, and the removal rates of Cu(II)/Ni(II) depend on the complete decomplexation. The removal rates of Cu(II) and Ni(II) was affected by the pH of solution, and the optimal pH was found to be 7-9; nevertheless, their removal rates can still be up to 90% even in acidic pHs of 3~5. When the molar ratio of EDTA to Cu(II)/Ni(II) increased from 1:1 to 3:1, the kinetics of metal ion removal rate declined from 0.0788 and 0.1139 min-1 to 0.0250 and 0.0271 min-1. The synergistic effect was found in the Cu(II)/Ni(II) blended system due to the higher catalytic capability and the lower complexation affinity toward EDTA for Ni(II). In summary, ozone oxidation can be considered as an effective technology to realize the complete decomplexation of Cu(II)/Ni(II)-EDTA that contained in chemical plating industry wastewater. Graphical Abstract.

Effect of Copper Chemical Form on The Growth of Pseudomonas aeruginosa Isolated from Burned Patients and on Its Cu Uptake

The main object of this investigation was to shed light on the information on the level of Cu uptake by Pseudomonas aeruginosa that has been previously isolated from patients using Gram-negative E. aerogenes ans a Gram-positive Bacillus thuringiensis as a control for Cu uptake measurements. Cu uptake data showed that maximum Cu uptake was obtained by the Pseudomonas aeruginosa. The metal uptake was dependent on the type of biosorbent with different accumulation affinities toward the tested chemical form of the copper. Cells harvested at exponential growth phase showed slightly higher Cu uptake than at stationary phase, which reflect that the Cu uptake is metabolism dependent-process. The increasing order of affinity of the cupric chloride and cupric sulphate towards the three genera were almost constant. However, where cupric nitrate was used, the copper uptake behavior in Pseudomonas aeroginosa was not changed from those results with the other two chemical forms, whereas with E. aerogenes & B. thuringiensis, different Cu uptake behaviors were observed. In B. thuengenesis, the copper uptake rate as a function of initial Cu concentration were shown to increase with increasing the initial concentration of Cu, constantly above 320 ppm as compared with others. In Enterobacter with cupric nitrate, different bahavior was also shown in which the copper uptake decline sharply beyond the 320 ppm. These results reflect that the Cu uptake in P. aeruginosa is with different mechanisms as compared with other tested bacteria

Removal of Cu(II) from wastewater by using mechanochemically activated carbonate-based tailings through chemical precipitation.

This work explored the feasibility of utilizing the copper tailings (CT) for removing copper from the waste mine water based on the mechanochemical activation. Batch experiments were performed to evaluate the influences of various experimental parameters like the dosage of CT, reaction time, initial concentration of Cu, and anion species. By cogriding copper solution with CT in the stirred mill (mechanochemical activation), over 99.5% of copper was removed and the residual copper concentration in the solution was less than 0.5 mg/L, reaching the discharge limit. This reaction was a chemical precipitation process. The calcite of CT played a major role in precipitating copper and had a better removal effect on copper in the copper sulfate solution than copper nitrate solution. For copper sulfate solution, the copper deposit was mainly posnjakite (Cu4(SO4)(OH)6·H2O). In the copper nitrate solution, the copper sediment might consist mainly of basic copper nitrate. The stability of the two reaction products was measured by leaching test. The result showed that the sediment obtained by this method was relatively stable and was not hazardous wastes.

Removals of Cu(II), Ni(II), Co(II) and Ag(I) from wastewater and electricity generation by bimetallic thermally regenerative electro-deposition batteries

The treatment of heavy metal ions in wastewater is of great significance for protecting the environment and human health. To improve the power density and removal efficiency of thermally regenerative ammonia electro-deposition battery and expand the concentration range of effective wastewater removal, a new method for removing Cu(II), Co(II), Ni(II) and Ag(I) from wastewater while generating high-power electric energy by using waste heat, called bimetallic thermally regenerative electro-deposition battery (B-TREB), was constructed in this work. For Cu(II)-containing wastewater with a wide concentration range of 0.002–0.3 M, the removal efficiency (RE) of Cu/Zn-TREB could reach more than 90%. With the initial concentration of Cu(II) being increased from 0.0005 to 0.3 M, the peak power density was enhanced from 20 to 546 W m−2. Besides, for 0.01 M and 0.1 M Co(II) wastewaters, the REs of Co/Zn-TREB were 85% and 90%, respectively. The RE of Ni/Zn-TREB was 88% for 0.01 M Ni(II) wastewater. These results illustrated that B-TREBs could remove many kinds of heavy metal ions in the wastewaters while maintaining a high removal efficiency of ~90% over a wide concentration range, and the produced high-power electricity could provide energy for further treatment or other uses.

Enhanced photocatalytic reduction of toxic Cr(VI) with Cu modified ZnO nanoparticles in presence of EDTA under UV illumination

In this study, the photocatalytic reduction of Cr(VI) to Cr(III) in aqueous solution using 1 wt% Cu/ZnO photocatalyst in presence of ethylenediaminetetraacetic acid (EDTA) under UV irradiation was investigated. The photocatalytic Cr(VI) reduction with ZnO under UV irradiation was significantly low. A fast Cr(VI) reduction with ZnO was recorded in presence of EDTA. Results demonstrated that the rate constant raised from 1.6 × 10−2 to 7.5 × 10−2 min−1 with 20 ppm EDTA addition. The optimum reduction (90%) was observed within 30 min at pH 3. The reduction efficiency of Cr(VI) was evidently increased from 6% to 99%, with increasing ZnO dosages up to 40 mg. The role of co-catalysts such as Au, Ag, Cu and NiO was also studied. The addition of Cu ion remarkably accelerated the reduction of Cr(VI), compared with ZnO/EDTA system alone. The Cu motivated ZnO/EDTA system completed the 99% reduction within only 30 min. The Cu ions were reduced to metallic copper and Cu2O by conduction band electrons of ZnO. The electron–hole recombination was gently declined by the shallow electron trapping of Cu. On the other hand, EDTA could be performed in two ways by forming Cr(III)-complex and separating Cr(III) from ZnO surface and by consuming valence band holes. The Cu modified ZnO photocatalyst was characterized by N2 adsorption- desorption isotherm, TEM, EDX, XPS, DRS and PL spectra. We evaluated the influence of pH, photocatalyst dosage, initial concentration of EDTA and initial concentration of Cu2+ ion (Cu doping amount) on photocatalytic reduction of Cr(VI). The pseudo first order kinetic reaction was confirmed for this reduction process. Herein, a probable mechanism of this photocatalytic reduction process was also presented.

Tween 80 Modified Hydroxyapatite as an Adsorbent for Removal of Copper from Aqueous Solution

Hydroxyapatite was in this study modified with Tween 80 through ultrasound assisted chemical precipitation method. The Tween-modified hydroxyapatite (T-HA) was characterized by some analytical methods. T-HA particles were rod-shaped with an average length of 59 nm. The effect of contact time, pH, temperature, adsorbent dosage and initial concentration of Cu2+ on adsorption capacity were studied to determine the capacity of T-HA to adsorb copper ions. The removal efficiency for Cu2+ reached maximum (82.68%), at an initial concentration of Cu2+ of 200 mg/L and adsorbent dosage of 0.1 g at 35 °C for two hours reaction. The adsorption mechanism was determined by pseudo-first-order (PFO) and pseudo-second-order (PSO) kinetic models, while the equilibrium isotherms was fitted by Langmuir, Freundlich and Dubinin-Radushkevich (D-R) models. Our data can best be described by a PSO kinetic model (R 2 = 0.99971) and D-R model (R 2 = 0.9377), suggesting a chemisorption mechanism. Application of Langmuir isotherm model (R 2 = 0.99337) indicated that Cu2+ was adsorbed on T-HA as a monolayer. These results demonstrated that the Tween-modified hydroxyapatite is a promising material for environmental remediation of copper ions in waste water.

Tween 80 Modified Hydroxyapatite as an Adsorbent for Removal of Copper from Aqueous Solution

Hydroxyapatite was in this study modified with Tween 80 through ultrasound assisted chemical precipitation method. The Tween-modified hydroxyapatite (T-HA) was characterized by some analytical methods. T-HA particles were rod-shaped with an average length of 59 nm. The effect of contact time, pH, temperature, adsorbent dosage and initial concentration of Cu2+ on adsorption capacity were studied to determine the capacity of T-HA to adsorb copper ions. The removal efficiency for Cu2+ reached maximum (82.68%), at an initial concentration of Cu2+ of 200 mg/L and adsorbent dosage of 0.1 g at 35 °C for two hours reaction. The adsorption mechanism was determined by pseudo-first-order (PFO) and pseudo-second-order (PSO) kinetic models, while the equilibrium isotherms was fitted by Langmuir, Freundlich and Dubinin-Radushkevich (D-R) models. Our data can best be described by a PSO kinetic model (R2 = 0.99971) and D-R model (R2 = 0.9377), suggesting a chemisorption mechanism. Application of Langmuir isotherm model (R2 = 0.99337) indicated that Cu2+ was adsorbed on T-HA as a monolayer. These results demonstrated that the Tween-modified hydroxyapatite is a promising material for environmental remediation of copper ions in waste water.

Effective Activated Carbon as Adsorbent for the Removal of Copper(II) Ions from Wastewater

Nitric acid activated carbons prepared from the barks of Limonia acidissima plant (NALABC) and stems of Hibiscus cannabinus plant (NAHCSC) are investigated as adsorbents for the removal of Cu(II) ions from waste water using batch methods of extraction. Various extraction conditions namely, pH, time of equilibration, sorbent concentration, initial concentration of Cu(II) ions and temperature, are optimized for the maximum removal. Substantial amounts of Cu(II) are extracted in the pH range: 3 to 9 and adsorption capacities are 19.6 mg/g for NALABC and 29.4 mg/g for NAHCSC, which are more than many active carbons developed in the previous works. It is interesting to note that the adsorbents are effective in acidic, neutral and also in basic conditions of the water samples and thus paving the way for applying these adsorbents in wide pH ranges of diverse samples. Five-fold excess of common co-ions that are normally present in water, have marginally affected the % removal. Thermodynamic parameters are evaluated for the spontaneity and nature of adsorption processes. The adsorption phenomenon is analyzed using Langmuir and Freundlich isotherm models and noted that Langmuir isotherm model suits better indicating the uniform and mono-layer nature of adsorption. Kinetics of adsorption is analyzed and found that pseudo second-order kinetics preferably explains the adsorption of Cu(II). The spent NALABC and NAHCSC can be regenerated and subsequently used. The adsorbents developed are found to be effective in removing Cu(II) ions from the real water samples collected from polluted lakes and copper based industries.