The calcined Cow Leather (CCL). Series of adsorption tests

The removal of copper (II), Zinc (II) andNickel (II) ions from aqueous solution using Calcined Cow Leather (CCL) byadsorption technique was investigated in a batch system. The final concentrations of Cu (II), Zn(II) and Ni (II) after the adsorption process was obtained using ICP-MS spectrometry.

Furthermore,a complete characterization study (FT-IR, XRD, SEM, XRF, and BET) demonstratedthe surface morphology of the calcined Cow Leather (CCL). Series of adsorption testswere carried out to determine the effect of solution pH on Cu (II), Zn(II) andNi(II) adsorption, contact time (kinetics fitted to linear pseudo-first,-second order equations and Elovich model), initial ions concentration , biomassloading and temperature (fitting to Langmuir, Freundlich andLangmuir–Freundlich equations). Results indicated that the adsorption of Cu(II), Zn(II) and Ni(II) ions increased with the increase of pH, temperature andbiomass loading and decreased with increase of initial Cu (II), Zn(II) andNi(II)) concentrations.

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The maximum biosorption capacity (qmax) for Cu(II) Zn(II)and Ni(II) respectively is 9.60 mg/g at the optimum biosorption conditions. Thermodynamicfunctions, the change of free energy (DG_), enthalpy (DH_) and entropy (DS_) ofbiosorption were calculated for copper(II) ion. The results showed that thebiosorption of copper(II) ion on tomato waste biosorbent was exothermic at293-313 K. Results of biosorption studies are in line with the literature.

Apromising outcome based on experiments shows that, tomato waste could be usedas an alternative and low-cost biosorbent for removal copper(II) ion fromaqueous solutions, when suitable conditions are performed.  Key words: Adsorption,copper (II), zinc (II), nickel (II), ICP-MS, Leather, isotherm,Langmuir, Freundlich    1.   INTRODUTIONHeavy metals constitute a group ofinorganic chemical hazards for the ecosystems and human health because of theirhigh toxicity in the industrial aqueous waste water. Heavy metals are naturally occurring elements that have ahigh atomic weight and a density at least 5 times greater than that of water 1.   Fordecades, water pollution has been studied because of the rapid industrialdevelopment which increased the production and use of heavy metals, resultingin high concentrations of heavy metals often being discharged into waterbodies. Industries such as mining 2, 3, tanneries, metal plating, fertilizerindustries, battery and pesticide production, ore refineries and the paperindustry 4 are the major contributing sources of heavy metal.

Heavy metals,such as zinc (Zn), lead (Pb), copper (Cu), iron (Fe), nickel (Ni), and cadmium(Cd) are toxic, carcinogenic, persistent in nature and tend to bioaccumulate 5. La source : Article 1 Severalmethods have been proposed for efficient heavy metal removal from water,including but not limited to chemical precipitation, ion exchange, membranefiltration and electrochemical technologies 6, 7, 8, 9, 10. Among thesetechniques, adsorption has proven the flexibility in design and operation and,in many cases it will generate high-quality treated effluent.

In addition,owing to the reversible nature of most adsorption processes, the adsorbents canbe regenerated by suitable desorption processes for multiple use 11, and manydesorption processes are of low maintenance cost, high efficiency, and ease ofoperation 12. Therefore, the adsorption process has come to the forefront asone of the major techniques for heavy metal removal from water/wastewater. This technology is cheap andenvironmentally friendly if low cost adsorbents are used.

In the search for lowcost adsorption materials over the past years, many researchers shifted theirinterests into the use of animal wastes, such as chicken feathers, animalbones, Ensis siliqua Shell, snailshells, …  13, 14, 15 ,16 . Since the cost of anadsorbent depends on its abundance, availability and effectiveness, animal wasteshave been extensively studied. There are many parameters that affect the efficiency of an adsorptionprocess, such as pH, temperature, adsorbent dosage and initial metalconcentration. For instance, pH may affect the metal availability, functionalgroups on the surface of the adsorbents and ionic strength17. In case ofadsorbent dosage and metal concentration, the efficiency mainly depends on theavailability of active sites and the competition for active sites 18.  Article1 The purpose of the present review is tostudy the feasibility of valorization anddevelop a new cost low biosorbent to remove heavy metals from wastewaters byadsorption technique using Calcined Cow Leather as a new abundant material andan eco-friendly biosorbent for the removal of Cu, Znand Ni from metal contaminated wastewater and evaluate the effects of pH,contact time, adsorbent dosage and initial metals concentration on metal uptakeand removal efficiencies.  The biosorption behavior wasanalyzed using the Langmuir, Freundlich, Temkin and Dubinin-Radushkevichadsorption isotherms.

The experimental data of adsorption kinetics wereanalyzed using the pseudo-first and pseudo-second order kinetic models and thethermodynamics of this process were also studied.  2.   Materials and methods 2.1. heavy metal ions preparationUnless otherwise stated, all chemicalreagents used in this study were of analytical grade.    Synthetic stock solutions of heavy metals (Cu(II), Zn (II) and Ni (II)) of 1000 mg/L were prepared in 1L of 0.5% HNO3distilled water by dissolving respectively, 3.

97g, 4.40g, and 4.52g of CuSO4.5H2O,ZnSO4.7H2O, and NiSO4.

6H2O fromMerck (Germany). HNO3 was used as an electrolyte to control theionic strength of metal ions. Desired test solutions of heavy metal ionswere prepared using appropriate subsequent dilutions from stock solutions. The resulting stock solutions were stored in air tightbottle. HCL and NaOH were obtained from Merck and used for pH value adjustment. 2.

2.Biosorbent preparation Cow leathers(CLs) were kindly supplied by a slaughterhouse’s management waste servicelocated in Casablanca city. Cow leathers were cleaned from blood and otherdirt, and salted immediately after that with common marine salt, in order toavoid degradation processes and development of micro-organisms and bacteria. Thenlet dry in open air for many days helping to a partial removal of water.

Afterthis operation, the CLs were transferred to an oven at 70°C for drying.Dried leatherswere showed a high resistance for grinding, the reason why we opted to cut itinto small pieces, then calcined for 4 hours at 525 °C.The materials were ground to a fine powderand rinsed with deionized water until the pH of the filtrate reached 7 and thendried for 24hours at 105°C.The final material was kept in plastic container andpreserved in a desiccator for further use and the Calcined Cow Leathers wereabbreviated (CCL).     2.3.Apparatus Iductively coupled argon plasma  Spectromètre ICP-OES iCAP 6000 (in)-Australian, was used for the determination of Copper, Zinc, Nickel concentrationsrespectively at 324 nm, 213 nm and 231 nm.

The pH was measured using a Metrohm pH meter 691,SWISS, provided with a glass electrode. The shaking of solutions was carriedout with a 3500 VWR, USA digital shaker. Stirring of solutions was carried outwith a magnetic stirrer Model Jenway 1000, England. 3.   Characterization of CCL adsorbent Chemical analyzes of the CCL powder wereperformed using a fluorescence spectrometer (Wavelength dispersion spectrometer- Axios type).

(Table 1)Fourier transform infrared spectroscopy(FTIR) analysis was performed in the 450-4000cm-¹, using aFT/IR-Vertex 70 spectrometer (Germany). (Figure 1)The morphology of the CCL powder, wasobserved using a FEI Quanta 200 instrument (USA) scanning electron microscope(SEM), the images of the microstructure have been obtained with a maximumvoltage of 10 kV.(Figure 2)The elemental composition of our material, hasbeen determined by Energy Dispersive X-rays Spectroscopy (EDXS): X’Pert Pro MPDPanalytical (Netherlands) with Cu anode as the source of X-rays at wavelength ?=1.54 Å. (Figure 3)The specific surface area was measured bythe BET method using a Pore Size using a Micromeritics ASAP 2020 apparatus(USA).