Assessment of Chemically Modified Lignocellulose Waste for the Adsorption of Cr (VI)

Abstract

Chromium (Cr(VI)) presents carcinogenic and mutagenic effects in living beings. Biosorption is an alternative to conventional technologies for the treatment of waste water. The aim of this study was to assess the use of corncob and orange peels modified with citric acid and calcium chloride, respectively, for the removal of Cr(VI) using a batch system taking into account pH and particle size. Biomaterial were characterized using an elemental and chemical analysis, and FTIR, in which was evidenced the presence of hydroxyl, carbonyl and carboxyl groups, belonging to the cellulose and lignin that are attributed for the presence of active centers which intervene in the adsorption process. Adsorption experiments through batch system were performed using a solution of potassium dichromate at 100 ppm, 150 rpm, varying pH (2, 3, 4 and 6) and particle size (0.355, 0.5 and 1 mm). From de results was found that maximum removal percentage was obtained at pH 2 and particle size of 0.355 using corncob and orange peels. Final concentration of Cr(VI) was determined by using the standard method ASTM D1687-02 with 1,5-diphenylcarbazide at 540 nm. Adsorption kinetics and isotherms were assessed with the best conditions found, in which the experimental data was adjusted to the Pseudo-second order and Freundlich models, respectively. R2 value greater than 0.95 suggests that the process is controlled by a chemical reaction leading the formation of multilayers. The performance of the biomass in terms of q0 was found to be: corncob>orange peels>corncob modified>orange peels modified.

Optimization of the Effect of Temperature and Bed Height on Cr (VI) Bioadsorption in Continuous System

“…The peak of 2927.94 cm -1 is attributed to possible vibrations of C-H methyl, methylene and methoxy groups, between 2000 and 2500 cm -1 there are signs of alkenes and carboxylic acids that may be due to the stretching of O-H. Peaks close to 1650 cm -1 are also recorded which indicate the presence of functional groups of cellulose, hemicellulose and lignin due to stretching of C=O and C-O by the vibrations of carboxyl groups of pectin, hemicellulose and lignin [1,19,21,22], and also may indicate the presence of aromatic rings due to hydrogen vibrations representing the stretching of C=C [23]. On the other hand, between 1000 and 1200 cm -1 evidence the presence of primary, secondary and tertiary alcohols, a product of the stretching vibrations of the C-OH bond and the bending between the plane (1225-950 cm -1 ) are only complementary signals because the C-C, C-N and C-O stretch fall in the same region and several signals appear depending on the number of hydrogen.…”

“…The residual biomass was dried for 8 h in the sun, subjected to size reduction and classified by choosing particle sizes between 2 mm and 1 mm. A 1000 ppm Cr (VI) stock solution was prepared using K2Cr2O7 (Merck Millipore), analytical grade, in deionized water; from this stock solution, it was diluted to obtain the different concentrations used in the adsorption tests [19].…”

Adsorción de cromo (VI) y mercurio (II) en solución utilizando jacinto (Eichhornia crassipes)

“…We worked with 100 mL of the solution with a concentration of 100 ppm and 0,5 g of biomass of each particle size of the biomass already crushed (0,355 mm, 0,5 mm and 1 mm) placing them in a Beaker with stirring for 2 hours at 150 rpm, extracting samples of 3 mL at the end of the agitation. The analysis of the final concentration of the metal in the liquid phase is carried out by the method of diphenylcarbazide and ammonium diocyanate at 584 and 281 nm, for Cr (VI) and Hg (II) respectively, in a UV-vis spectrophotometer [5,18]. The experiments were carried out in duplicate.…”

“…In this context, adsorbents of vegetable residual origin have been used for water cleaning, among them: tea, coffee waste, watermelon seed husks, ceiba fiber, palm bagasse, yam and yucca husks, peat, fly ash, cellulose, fungi immobilized in nanosilica, orange peels, Kikuyo, among others [14][15][16]. Cu, Al, As, Hg (II), Fe, Ni, Ca and Pb, have been removed using bioadsorbents from water buffon, finding that this biomass of lignocellulosic origin has good percentages and removal capacities of metal ions as well as of phenolic compounds, due to its lignoelulósica nature and the presence of hydroxyl and carboxyl groups that benefits the removal [17,18]. Therefore, in the present study the water hyacinth is used in the removal of Hg (II) and Cr (VI) from a synthetic aqueous solution in a batch system.…”

Determination of Kinetic Parameters in the Biosorption of Chromium (VI) in Aqueous Solution

“…The synthetic solution of Cr (VI) was prepared using 0.2828 g of potassium dichromate (K 2 Cr 2 O 7 ) in 1 L of deionized water to obtain a concentration of 100 ppm of the solution, which pH was 2 [23], [24].…”