Tenacissima L. (Alfa) Plants: Kinetics, Equilibrium and [PDF]

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APTEFF, 52, 1-273 (2021) DOI: https://doi.org/10.2298/APT2152033L

UDC: 66.067.8.081.3:582.542.1:667-12 BIBLID: 1450-7188 (2021) 52, 33-44 Original scientific paper

REMOVAL OF METHYLENE BLUE BY BIOSORPTION ONTO STIPA TENACISSIMA L. (ALFA) PLANTS: KINETICS, EQUILIBRIUM AND THERMODYNAMIC STUDIES Samir LADJALI1,2*, Nadjib DAHDOUH1, Samira AMOKRANE1, El hadj MEKATEL1, Djamel NIBOU1 1

Laboratory of Materials Technology, Faculty of Mechanic and Engineering Processes (USTHB) BP 32, 16111, Algiers, Algeria 2 Process Engineering Department, Faculty of Science and Technology, Mustapha Stambouli University-Mascara, Mascara, Algeria

Received: 27 September 2020

Revised: 12 February 2021

Accepted: 17 February 2021

This study examines the ability of Stipa tenacissima L. (Alfa) to biosorb the Methylene Blue dye. Biosorption tests were performed in aqueous solution based on certain essential parameters such as solution’s pH (2-12), solid/liquid ratio (1-6 g/L), initial dye concentration (25-125 mg/L) and contact time (0-300 min). The Langmuir, Freundlich, Temkin and Elovich models were applied. It was found that the equilibrium data could be fitted to the Langmuir isotherm for MB biosorption with a maximum capacity qmax 55, 95 mg/g. The kinetic study shows that the experimental data correspond to the pseudo-second order kinetic model. The negative Gibbs values free energy ΔG° reveal the spontaneity of MB biosorption at the surface of Stipa tenacissima L. The positive value of ΔH° reveals the endothermic nature of the process. Keywords: Stipa tenacissima L (Alfa), methylene blue, biosorption, kinetic study and thermodynamic.

INTRODUCTION Nowadays, environmental protection has become a major concern in all countries. Therefore, there is an urge for encouraging the development of processes for the improvement of waste-water treatment methods focusing on the reduction of pollution sources. However, industrial effluents from textile, tanning, or printing activities often have high colored pollutant loads which are difficult to biodegrade. The discharge of highly colored compounds such as dyes can block out sunlight penetration in surface waters, hence decreasing both photosynthetic activity and dissolved oxygen concentration and affecting aquatic life (1). Unfortunately, during the dyeing process, large fractions of reactive colors (10-50 percent) are wasted and an estimation is that over 7105 tons of dyes are produced each year (2). This is why many researchers within the water treatment field are interested in the removal of reactive dyes. Several conventional treatments have proven ineffective in removing supplements and dyes due to their high-water solubility. Furthermore, various techniques have been used in the process of eliminating some soluble pollutants from industrial or domestic effluents. They are different from each other and can be cited for illustration purposes: adsorption (3), electrolysis (4), combined Adsorption/Photocatalysis (5), liquid-liquid extraction (6), mem* Corresponding author: Samir Ladjali, Process Engineering Department, Faculty of Science and Technology, Mustapha Stambouli University-Mascara, Algeria, e-mail: [email protected]

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APTEFF, 52, 1-273 (2021) DOI: https://doi.org/10.2298/APT2152033L

UDC: 66.067.8.081.3:582.542.1:667-12 BIBLID: 1450-7188 (2021) 52, 33-44 Original scientific paper

brane filtration (7), coagulation-flocculation (8), etc. The best prospect for dye removal tends to be adsorption on activated carbon. This adsorbent is costly and hard to recycle after use despite its efficiency. A wide variety of inexpensive adsorbent materials, such as clay minerals, have been identified in recent years (9) and biomasses (10). Most of the materials studied include wastes of aquatic and agro-industrial origin like seaweed, microbial biomass, pine bark, cotton, beet pulp, pine sawdust, sugarcane bagasse, jute fibers, olive kernel, coconut, and rice husks (11). The studies available in the scientific literature indicate that the biosorbents can be an alternative to the activated carbons in water treatment processes on an industrial scale (12). Thereby, this paper examines the treatment of water-containing dye such as methylene blue (MB) by following the adsorption process that is based on the retention of a pollutant by an adsorbent. In this case, it is a natural lignocellulosic material whose stems were chosen as the biosorbent. This study aims first and foremost to valorize this local resource which is abundant in Algeria and to determine its biosorption capacities regarding the dye. The fundamental investigations, mainly, include the characterization of biosorbents, biosorption equilibrium, kinetics and thermodynamics. Determination of biosorption kinetics is crucial in predicting the behavior of a biosorbent in practical applications (13). Stipa tenacissima L. is also known as Alfa in the studied region (the Arabic name for the plant) like belongs to the grass family. It is widespread in arid regions in northwest Africa and southern Spain. This wild plant covers large areas of the Algerian highlands and usually blooms in the period time from April to June. However, it is a permanent plant that survives the winter. It grows up to approximately one-meter height in the form of a cylindrical rod. Like any lignocellulose/lingnocellulosic biomass, Alfa stems are hard, its Latin name is (Stipa tenacissima L.), low density, abundant in nature, renewable and 100% biodegradable. The untreated plant, namely Stipa tenacissima L., is examined in this study. Methylene blue, a cationic dye, was used as a molecular model to study the biosorption properties for the removal of the typical dye (14). EXPERIMENTAL MATERIALS Biosorbent preparation The Alfa biomass stems were manually washed with tap water to remove debris, dust, and sand, and then it was thoroughly rinsed with distilled water, dried in the open air for 24 hours, and then warmed up in an oven at 80 °C for 48 hours. To grind the biosorbent, the biomass was immersed in liquid nitrogen for 15 minutes to harden and weaken the stems to facilitate the grinding process. Afterwards, they were easily crushed with a domestic mortar. Then, the ground powder was sieved (powder fraction