Removal of wood dyes from aqueous solutions by sorption on untreated pine (Pinus radiata) sawdust

Abstract

In this work, the possibility of using un-treated pine (Pinus radiata) sawdust as biosorbent for the removal of three wood dyes (blue, red and black) from aqueous solutions was investigated. The BET surface area of the material was 1.55 ± 0.81 m2 g−1 using N2 at − 196 °C and 17.83 ± 0.032 m2 g−1 using CO2 at 0 °C. The point of zero charge was 4.8. In addition, the material was characterized before and after adsorption by surface analytical techniques. Assays were performed to analize the stability of wood dyes with time and pH and also to estimate the pKa values. Batch adsorption experiments were performed and the influence of experimental parameters such as contact time (up to equilibrium), stirring rate (100 and 210 rpm), adsorbent dose (2–10 g L−1), pH (2–9) and initial dye concentration (5 and 300 mg L−1) were studied. The optimum conditions were pH 2 and adsorbent dose of 6 g L−1 and the highest adsorption percentages achieved at 5 mg L−1 were: 100.0% for the blue, 99.7% for the black and 92.4% for the red. For 300 mg L−1 adsorption efficiency decreased to 85.6, 57.0 and 63.8% for the blue, black and red ones, respectively. Kinetic data were best fitted to the pseudo-second order model, suggesting a chemisorption process. Freundlich and Dubidin-Radushkevich were the best isotherm models. Regeneration study showed that un-treated pine sawdust could be reused efficiently for red dye removal at least in up to four repeated adsorption–desorption cycles using NaOH as desorption agent.

Valorization of Lemon Peel as low-cost adsorbent for the removal of Basic Fuchsine and Eosin dyes from aqueous solutions

“…The value of E is used to specify whether the adsorption is controlled via a physical (E < 8 kJ•mol -1 ) or a chemical process (8 < E < 16 kJ•mol -1 ) [67]. The results are presented in Fig.…”

The Use of Rapeseed Husks to Remove Acidic and Basic Dyes from Aquatic Solutions

“…Sorption involves binding contaminants on the surface of the material (sorbent). Unlike precipitation or deep oxidation methods, it does not generate any by-products [10]. Sorption methods are also easier to carry out and are cheaper compared to the membrane methods.…”

The Use of Various Types of Waste Paper for the Removal of Anionic and Cationic Dyes from Aqueous Solutions

“…The largest group of sorption materials tested so far was lignocellulosic plant biomass [ 13 , 14 ], including stems [ 15 ] and leaves of crops [ 16 , 17 ], seed hulls [ 18 , 19 ], nut shells [ 20 , 21 ], as well as fruit [ 22 , 23 ] and vegetable peels [ 24 , 25 ]. Ample studies have also been carried out on the removal of dyes using waste from the wood industry, such as sawdust [ 26 , 27 ], bark [ 28 , 29 ], cones [ 30 , 31 ], or tree leaves [ 32 , 33 ]. In some cases, scientists have reported that the sorption capacities of the tested plant sorbents were similar to those of some types of activated carbons [ 34 , 35 ].…”