Equilibrium and Kinetic Studies on the Removal of Cu(II) from Aqueous Solution Using Acid Treated Modified Rice Husk: A Comparative Study

This study deals with the removal of Cu(II) using rice husk and its acid treated modified form as adsorbents under batch experiments. Different parameters have been investigated for the adsorption of copper metal. Equilibrium time (90 min) was found for copper adsorption. Maximum percentage for removal of Cu(II) was found at pH=4 both for raw rice husk and its treated form. Percentage removal of copper metal was up to 90% for treated rice husk and up to 70% for raw form of rice husk. The pseudo second order kinetic model provided the best correlation of the used 2 experimental data compared to the pseudo first model with a R of 0.984 and 0.979 for

control pH of the wastewater. All analytical grade reagents were used in this study

Preparation of Bio-sorbent:
First of all, rice husk was washed with distilled , high usage of chemicals, large water. Dried rice husk was crushed and passed amount of sludge formation [10].
through series of mesh size and collect the material Cost effective methods are needed to remove heavy retain on sieve of mesh size 42 of Taylor sieves of metals from wastewater. Agricultural waste is also series. Rice husk was treated with 0.1N nitric acid use for metal removal from waste water as a sorbent solution and then washed with distilled water till such as coconut husk, sawdust, rice straw, wheat neutral pH was obtained. Bio sorbents materials straw etc. Advantages of using these materials must be store in air tight cause saving in cost and utilization of wastes [11][12].
One of the strategic crops of the world is rice. A great amount of rice husk is produced every year in Pakistan. Rice husk is made up of crude protein, ash, lignin and cellulosic materials etc. Rice husk can be used to remove Cu from water.
From the last decade, focused has been made on use of rice husk in its different forms such as treated form, ash form or pyrolysis form as a bio sorbent for re made by diluting removal of heavy metals. Different treatments for 1000ppm this stock solution. 100 ppm of sample rice husk were reported for the enhancement of solution of copper was used for each experiment. adsorption capacities for metal ions and other Mixing was performedon vibratory shaker with 150 pollutants [13].
rpm. Effect of contact time, pH, adsorbent dosage In this study, rice husk was used as a bio sorbent in and initial metal concentration on biosorption of raw form and acid treated modified form to removed copper have been investigated copper metal ions. Comparative performance evaluation of different forms of same biomass i.e., raw, chemically modified and ash is necessary. Rice husk and their modified forms have been tested for the wastewater treatment under different conditions under batch experiments. (NaOH) purity 99% were procured from Sigma Aldrich, USA. Rice husk was obtained from Jeddah rice mill, Multan, Pakistan. Standard solution of copper Sulfate was prepared for atomic absorption spectrometry. Nitric acid was used for the preparation of treated rice husk. 0.1mol/L NaOH Figure (1-2) represents the relationship between Different method such as membrane process, dialysis, extraction of solvent, reverse osmosis is also used but most of them have many drawbacks such as high cost vessels for its protection from humidity or moisture.

Cu(II) Contents Detection:
Flame atomic absorption spectrometry FAAS (Shimadzu 6800) with cathode lamp of 232nm and 15mA was use for the detection of contents of Cucontents.

Experiments:
Stock solution of copper sulfate (1000ppm) was made. Different synthetic samples of initial different concentrations we

Uptake Of Copper By Bio Sorbent:
Amount of copper metal ions on rice husk bio sorbent is calculated [13]   1revealed that no metal uptake after 90 minutes was take place. It was found that about 70% copper is adsorbed by the untreated rice husk. The reason behind that the vacant surfaces were available at the start of biosorption which is decreases with the passage of time due to occupancy of metals on the surface [14]. Figure 2 represents contact time and Cu(II) metal uptake using raw rice husk and treated rice husk at different pH with bio (0.2 gram) and temperature(30±1) Cand initial sorbent amount (0.2 gram) and temperature (30±1) metal ion concentration (100mg\L).
C a n d i n i t i a l m e t a l i o n c o n c e n t r a t i o n (100ppm). Figure (3-4) depicted the copper metal uptake as 35mg/g and 40mg/g at pH=3 both for raw and treated rice husk respectively. On the other hand, Figure (5-6) revealed the copper metal uptake as 37mg/g and 45mg/g at pH=4 for both cases. While Figure (7-8) showed the copper metal uptake as 32mg/g and 38mg/g at pH=5 both for raw and acid treated of bio sorbent. It is concluded from the above discussion, the maximum removal of copper from water sample was found for pH-4 that may be due to high active sites present on the surface of bio sorbent [13].   uptake at pH=3, dose=0.2g, concentration= 100ppm Figure (3-8) represents the relationship between using treated rice husk uptake at pH=5, dose=0.2g, concentration =100ppm using raw rice husk using treated rice husk

Effect of initial metal concentration:
Figure (9-10) represents the relation of initial concentration of metal on the Cu (II) metal uptake using raw rice husk and treated rice husk with bio sorbent amount (0.2 gram) and temperature (30±1) C and pH=4. Figure 9 depicted that the copper metal uptake was found maximum at an initial metal concentration of 100ppm for raw rice husk. While Figure 6: Effect of contact time on copper metal uptake at pH=4, dose=0.2g, concentration =100ppm using treated rice husk. Figure 9: Effect of initial metal concentration on Figure 7: Effect of contact time on copper metal copper metal uptake at pH=4, dose=0.2g using raw uptake at pH=5, dose=0.2g, concentration =100ppm rice husk using raw rice husk   Figure 12: Effect of adsorbent dose on copper copper metal uptake at pH=4, dose=0.2g using metal uptake at pH=4, dose=0.2g, concentration= treated rice husk 100ppm using treated rice husk

Kinetic Modeling: 3.4 Effect of adsorbent dosage:
Kinetic model tells us about the mechanism of Figure (11-12) represents the effect of adsorbent adsorption of metal [15][16][17]. Equation (2-3) dosage of bio sorbent on the Cu (II) metal uptake for represents the pseudo kinetic model of first order in raw and treated rice husk with its differential and integral form respectively [18]. temperature Figure (13-14) revealed the first order kinetic model 2 (30±1) C and p with R values of 0.6 ther hand, Figure 12 revealed the maximum removal of copper metal at adsorbent dosage of 0.2 g. q = Uptake capacity (mg/g) t t =Time (min) -1 k = Equilibrium rate constant (min ) 1 q = Equilibrium capacity (mg/g) e Figure 11: Effect of adsorbent dose on copper metal uptake at pH=4, dose=0.2g, concentration= Figure 13: Pseudo first order kinetic model for raw 100ppm using raw rice husk. rice husk.
initial metal concentration of 100ppm along with H=4. Figure 11 showed that the 568 and 0.6898 for raw and copper metal uptake was decreases with the treated adsorbents respectively and these could not  On the other hand, equation (4-5) represents the pseudo kinetic model of second order in its q = Uptake capacity (mg/g) differential and integral form respectively [18] (4) 2020 Moval of Cu (II) from wastewater using rice husk as Metal Ion from Waste Water by Using a bio sorbent in its raw and treated form. It is Soybean Hulls and Sugarcane Bagasse as concluded that treated rice husk has more potential Adsorbent" IJSRR, 1(2), 13-23, 2012 to remove copper metal than raw rice husk. Number 4. J. Zhang, H. Fu, X. J. Tang, X. Xu, "Removal of of active sites, functional group enhancement and high ion-exchange properties were enhanced due to Cu(II) from aqueous solution using the rice chemical treatment of rice husk. Equilibrium time husk carbons prepared by the physical for adsorption was achieved up to 90 mins. The activation process", Biomass and bioenergy, adsorption was found maximum at pH=4 in both 35 464e47, 2011. cases. Kinetic modelling revealed the pseudo model of second order was best fitted both for raw and 5. C. Gonc¸ A. Rocha, D. Augusto, M. Zaia, R. V. treated form of rice husk. More comprehensive da Silva Alfaya, A. A. da Silva Alfaya, "Use of research should be done to find the most costrice straw as biosorbent for removal of Cu(II), effective method of rice husk treatment to improve Zn(II), Cd(II) and Hg(II) ions in industrial its adsorption capacities.
effluents", Journal of Hazardous Materials,