Preparation and Characterization of Copper Oxide Nanoparticles Used to Remove Nickel Ions from Aqueous Solution

In this study, copper oxide nanoparticles (CuO) was prepared by simple precipitation method and then it characterize by XRD, SEM, and AFM techniques. XRD spectrum revealed that particle size obtained was around (7.43 nm) for it, which agreed fairly well with XRD data. Surface morphology as a main nanoparticles phenomenon was studied in terms of SEM and AFM. The prepared oxide nanoparticles was used to remove nickel ions from aqueous solution and determining the best removal percentage at different contact time (30, 60, 90, and 120 min) and different initial concentration of aqueous solutions (100, 200, and 300 mg/L) with other constant condition such as pH of 3.5, adsorbent dosage (0.1g), and room temperature . The result showed the percentage removal of nickel ions increase with increase in the contact time, and the maximum adsorption was recorded with 100 mg/L for the prepared oxide nanoparticles, Also the percentage removal seem to decrease with increase in the initial concentration of adsorbate. The correlation coefficient for the linear Freundlich isotherm regression fits are larger than that for the Langmuir one for (CuO), nanoparticles, so the Freundlich model could describe the adsorption isotherm for the uptake of nickel ions from aqueous solution on(CuO), nanoparticles surfaces.


Introduction
Copper oxide is one of the important metal oxide which has attracted recent research because of its low cost, abundant availably as well as its particular properties [1].It is one of semiconductors material and gains considerable attentions due to its excellent optical, electrical, physical, and magnetic properties, and it is non-toxic and easily obtained by the oxidation of Cu [1,2].CuO crystal structures possess a narrowband gap, giving useful photocatalytic and photovoltaic properties [3].
of the blood-brain barrier in vivo in mice and rats.[1].
Lately, application of nanoparticles for the removal of pollutants has come up as an important area of research.The unrivaled properties of nanosorbents are providing unmatched occasion for the uptake of metals in highly efficacious and cost-effective approximation, and different nanoparticles show good adsorption efficiency mostly because higher surface area and larger active sites for interaction with metallic species.Furthermore, adsorbents with specific functional groups have been advanced to ameliorate the adsorption capacity [5].
Copper oxide nanoparticles have been prepared with different sizes and shapes via several methods such as sonochemical, alcohothermal synthesis, vapor deposition, electrochemical methods, combustion ,colloid-thermal synthesis process, and microwave irradiation ,thermal oxidation ,pulsed wire explosion methods [1,2,6].There are some techniques for the synthesis of copper oxide nanoparticles that have been reported recently such as the sol-gel technique, thermal decomposition of precursors one-step solid state reaction method at room temperature, and co-implantation of metal and oxygen ions [7].Most of these techniques are intricate and have drawbacks like use of hazardous organic solvents, toxic by product, expensive reagent, drastic reaction condition, difficult to isolate nanoparticles and longer time required etc. [6].Among these processes, precipitation method is a facile way which attracts considerable interest in industries because of low energy and temperature, inexpensive and cost-effective approach for large scale production and good yield.However, these CuO novel properties can be

Characterization of Copper Oxide Nanoparticles, CuO :
The X-ray diffraction pattern of the prepared oxide were recorded using XRD-6000 with Cukα

Separation of Nickel Ion by Adsorption Technique:
A stock solution containing nickel ion was prepared by dissolving a known quantity of Nickel (II) Chloride in deionized water.Batch adsorption studies were performed by mixing 0.1gm of copper oxide nanoparticle with 50 ml of solutions with different nickel ions concentrations (100, 200, 300 mg/L) in 100 ml volumetric flask and the pH value was adjusted to 3.5 using 0.5M H₂SO₄ and 0.5M NaOH.All the experiments were performed at room temperature of 25±1 o C in a shaker water bath at a contact time of (30, 60, 90 and 120 min) and after that the samples were filtered off and the concentration of nickel ions measured.The particle size were calculated from Deby -Scherrer formula [8] in equation ( 1)

Result and Discussion
Where D is the crystallite size , λ is the wave length of radiation , θ is the Bragg's angle and β is the full width at half maximum (FWHM) [8] For copper oxide nanoparticles and it was 7.43 nm, The presence of sharp peaks in XRD patterns and crystallite size of less than 100 nm suggest the nano crystalline nature of all oxides.

Scanning Electron Microscope
The surface morphology of the prepared copper oxide nanoparticles (CuO) were revealed

Figure (2): SEM image of copper oxide nanoparticles, CuO Atomic Force Microscope
The AFM analysis provides a measure of average of grain size [10].The contact time between copper oxide nanoparticle oxide nanoparticles (Adsorbent) and nickel ions (adsorbate) that is sufficient for the adsorption process to reach equilibrium at room temperature of 25±1 o C using a fixed concentration (Co = 100 mg/L ) and adsorbent dosage (0.1g) .andpH of 3.5 were studied at different times (0 , 30 , 60 , 90 and 120 ) minute.Table (5), show the changes of nickel ion removal and percentage removal at contact time of ( 0 , 30 , 60 , 90 , and 120 ) minutes using copper oxide nanoparticles, (CuO) , and the results are presented in Figure ( 5) also .It was observed that the increasing in contact time lead to increase in percentage nickel removal and this is due to the larger available surface area of the nanoparticles.Nickel adsorption percentage in the initial stage depends on increase Abundance in active binding site numbers on the surface of adsorbent.Finite mass transfer of the adsorbate molecules from the bulk to the adsorbent surface cause to gradual increase in adsorption subsequently realization of the equilibrium adsorption [11][12][13][14].

Effect of The Initial Concentration of Nickel Ions on Its Adsorption
The adsorption experiment was carried out at room temperature of 25±1 o C with different initial concentration Co (100 , 200 , 300 mg/L) and keeping the adsorbent dosage (0.1g) and pH of 3.5 at contact time of ( 0 , 30 , 60 , 90 , and 120 ) minutes.Table (6) show the variation of percentage of nickel ion removal and residual and initial concentration of nickel ions using copper oxide nanoparticles, (CuO), and also represented diagrammatically in Figure (6).The results indicated that the percentage of nickel ions removal decreases with the increase of initial metal ion concentration increasing the initial concentration of Ni(II) in a batch study, a saturation point appears which resulted in decreased percentage of Ni(II) removal and this is due to the fact that after the formation of mono ionic layer at low concentration over the adsorbent surface, further formation of the layer is highly hindered at higher concentration due to interaction between nickel ions on the surface and in these solution [11,13,14].From Table (9) , the results show based on the correlation coefficient data for adsorption of nickel ions from aqueous solution on copper oxide nanoparticles ,which fit better to Freundlich isotherm model than the Langmuir one.So the adsorption of nickel ions was best described by the Freundlich isotherm model [12] .The results indicated that the mono layer adsorption

Materials used :
Analytical grade materials was used without any further purification in addition to deionized water and as shown in tables (1,2) : Table (1): Materials used in copper oxide nanoparticles, Copper oxide nanoparticle ,CuO were synthesized by precipitation method , In which 600 ml of copper (II) acetate and 5 ml glacial acetic acid were mixed in beaker, and the mixture heated to boiling .Then 30 ml of sodium hydroxide solution was added to the mixture to notice the solution color turned from the blue color to black one directly and the black precipitate start forming, where the reaction performed at boiling temperature with a continuous stirring for 3 hours.The mixture thus obtained cooled to room temperature and separated by centrifuge and (CuO) No:2 , April 2017 DOI: http://dx.doi.org/10.24237/djps.1302.265BP-ISSN: 2222-8373 E-ISSN: 2518-9255 nanoparticle, that obtained is filtered off and washed with deionized water and absolute ethanol for several times, and the precipitate was dried at 60 °C for 8 hours to produce (CuO) nanoparticles.
(λ=1.5406A°) that have an accelerating voltage of 220/50 HZ which is produce by SHIMADZU company.The scanning electron microscope (SEM) used in imaging the nanoparticles was a scanning electron microscope AIS2300C .Atomic force microscopy (AFM) used to study surface morphology of the samples was AFM model AA 3000 SPM 220 V-angstrum Advanced INC , USA, and finally elemental concentration analysis was measure by atomic absorption spectrometer type AURORA TRACE AI 1200.
diffractometer has been used to investigate the structure of copper oxide nanoparticles.XRD patterns of copper oxide nanoparticles are shown in Figure (1), also the data of strongest three peak are shown in Table (3).The positions and intensities of peaks are in a good agreement with those reported in JCPDS file NO. 48-1548 for copper oxide nanoparticles.

P 2 Figure ( 1 )
Figure (1) : XRD pattern of copper oxides nanoparticles, CuO through the SEM image shown in Figure (2) , it show a homogeneous distribution of spherical shape like nanoparticles with irregular distribution.From SEM images it is confirmed that the No:2 , April 2017 DOI: http://dx.doi.org/10.24237/djps.1302.265BP-ISSN: 2222-8373 E-ISSN: 2518-9255 particles having size in between 50 -70 nanometers by simple counting and calculations of number of particles and their sizes and this confirm the nanostructure nature of the oxide.

226Vol: 13 Figure( 5 )
Figure(5): Effect of contact time on percentage removal of nickel ions using copper oxide Nanoparticles, CuO at different initial concentration.
Figure (9): Linear Freundlich isotherm of nickel ions adsortion on copper oxide nanoparticle, (CuO) surface at different contact times.