Synthesis of Gelatin-Cellulose Nanocrystals Hydrogel Membrane For Removal of Cu (II) And Co (II) From Mining Processes Wastewater

10 This study describes the removal of Cu (II) and Co (II) ions from mining processes wastewater 11 using synthesis of Gelatin-cellulose nanocrystals (CNCs) hydrogel membrane (GCHM). In a 12 batch experiment, the influence of different parameters such as pH, contact time, temperature, 13 and ratio of gelatin and CNCs was evaluated. Higher removal efficiency was obtained at ratio 14 3÷1 and at pH 5 and 7 for Cu (II) and Co (II), respectively, and a contact time of 120 mins and 15 a temperature of 30°C. The experimental data fitted satisfactory to Freundlich isotherm model. 16 The adsorption of metal ions has been fit by the particle diffusion model. The results revealed 17 that gelatin and CNCs were identified as the low-cost and promising adsorption material for 18 the removal of heavy metals from wastewater.


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Adsorbate, adsorbent preparation and sampling procedure 56 Wastewater samples were collected from mining plant effluent in Rustenburg, South Africa.

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The samples were placed in 1000 mL plastic bottles, hold in cooler boxes and stored overnight 58 in the fridge prior to the experiments. The characteristics of the wastewater used in the 59 experiments is presented in Table 1. 60 All chemicals and reagents used in the work were analytical reagent grade purchased from 61 Sigma-Aldrich, South Africa. Adequate quantities of CNCs and gelatin (purity ≥ 98%) were 62 supplied by CSIR and dispersed in 50 mL of water. The CNCs suspension was then 63 homogenized using a homogenizer to ensure the CNCs suspended uniformly. Certain amount 64 of gelatin was then added into CNCs suspension. The mixture was then stirred at 55°C until a 3 homogeneous viscous mixture was obtained. Table 2 presented the ratios composition of 66 GCHM hydrogel.

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The cross-linking agent (EDTA 1%) was then added drop wise. After 4 hours, the mixture was 68 poured into a petri dish and placed in oven at 45°C until the mixture was dried. Hydrogels as 69 films were removed from the petri dish and washed with distilled water to remove unreacted 70 chemicals. The unreacted chemicals have been removed from hydrogel using acetone (Yao, 71 2019; Yin and Amin, 2014).

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Batch adsorption experiment 73 The adsorption of Cu (II) and Co (II) ions by GCHM was tested in batch experiment. A shaker 74 was used for mixing the solution. Several operational parameters were optimized, and this 75 includes effects of pH, gelatin-CNCs ratios, contact time and temperature. To ensure validity 76 of the results and reputability, all experiments were performed in triplicate and the data were 77 reported as an average value at 95% confidence level (p > 0.05). Heavy metal ions uptake 78 capacity and the removal efficiency were calculated using Equations 1 and 2, respectively.  The effect of temperatures ranging between 30°C and 75°C was investigated using thermo-   The SEM was used to observe the change in the morphological structure of the Gelatin- 6 The result in Figure 7 shows that the percentage removal of both ion metals increased with and Co (II) and the mass adsorbent (0.25 g/100 mL).

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Effect of temperature 184 It has been observed in Figure 9 that the negative effect of the temperature on the adsorption 185 of Cu (II) and Co (II) onto GCHM. The percentage removal decreases while the temperature 186 increases from 30°C -70°C.

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The percentage removal of Cu (II) and Co (II) was decreased from 70.5 to 30.8% and from 188 63.8 to 24.1% at pH 5 for Cu (II) and Co (II), respectively. At pH 7, the percentage removal 189 decreases from 69.1 to 27% and from 74.5 to 32.2% for Cu (II) and Co (II), respectively. The

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The best fit for an isotherm is giving by an R 2 closest to 1. The adsorption isotherms for Cu 218 (II) and Co (II) were studied using ratio 3÷1 for a mass of 0.25 g at 303 K. The data obtained 219 from linear Langmuir, Freundlich and D-R isotherms plot from the adsorption of Cu (II) and 8 The results reported in Kinetic studies 229 The kinetic parameters for the adsorption process were studied on the batch adsorption at pH

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From the values of R 2 represented in Table 4, it was observed that both metal ions are fitting 240 the pseudo first order kinetic.

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Kinetic diffusion 242 Kinetic diffusion mechanism has been investigated in order to determine the nature of were taken for Cu (II) and Co (II) ions and presented in Table 5  The results obtained in this study prove that GCHM is a potential and useful low-cost material 282 for the removal efficiency of Cu (II) and Co (II) ions from mining processes wastewater.

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Optimum removal of both heavy metal ions was obtained at ratio 3÷1 and at pH 5 and 7 for Cu   Table 1. Characteristics of the mining plant effluent used.    The SEM images of GCHM A (25÷75%), B (50÷50%), and C (75÷25%) Figure 6 Effect of pH on the removal of Cu (II) and Co (II), Ratio 3÷1 at 30oC Figure 7 Effect of ratio on percentage removal of Cu (II) and Co (II), pH 5 (A) and pH 7 (B), 120 min at 30oC Effect of Temperature on the removal of Cu(II) and Co(II), Ratio 3÷1, pH 5 (A) and pH 7 (B)