Adsorção de metais tóxicos em efluente aquoso usando pó da casca de coco verde tratado

Abstract

The solid agroindustry residues are most studied, due its abundance and low cost for recovery of wastewater industry using process of adsorption. In this work was used the green coconut shell powder as adsorbent for the heavy metals removal from wastewater aqueous produced for electroplating industries localized in Juazeiro do Norte (Ceara-Brazil). Adsorption systems in batch and column were studied. In the first step of this work was investigated the chemical treatment, the particle size effect, adsorbent concentration and pH effect. The results showed that the treatment employed in the green coconut shell powder with NaOH 0.1mol.L-/3h was the most efficient. This material was used for the metals adsorption study with the following characteristic: particle size ranged 60-99 mesh, adsorbent concentration (40g/L) and pH 5.0. The kinetic study indicated that the adsorption equilibrium multielementary were achieved in 5 minutes (pH 5.0) and followed a pseudo-second order model. The maximum capacities of adsorption observed for the multielementary system were: 7.89; 1.72; 3.24; 13.26 and 5.09mg/g to Pb+2; Ni+2; Cd+2; Zn+2 and Cu+2, respectively. In the second step of the work were carried out experiments to otimization of the operational parameters of the column. The results showed that for a flow rate of 2mL/min and height bed of 10cm there is an increased on the metals removal. The breakthrough curves investigated to a system multi indicated that the order for column capacity was the follow: Cu+2 > Pb+2 >Cd+2 > Zn+2 > Ni+2. The parameters optimization of the column obtained with the synthetic effluents were applied in a real sample contained (Ni+2, Zn+2 and Cu+2) which showed that the toxic ions removal increased at pH 5.0. The desorption of the metals ions retained on the column was efficient using the HNO3 1,0mol.L- as eluent. The tests of recycling of the column showed that the adsorbent can be used only a cycle.