Boreskov Institute of Catalysis of the Siberian Branch of Russian ...

LIGNOSULPHONATE TOTAL ORGANIC CARBONTREATMENT USING ELECTROCHEMICAL OXIDATIONA. Dominguez-Ramos, A. Fuente-Martin, R. Aldaco and A. Irabien *PP-II-14Departmento de Ingeniería Química y Química Inorgánica, Universidad de Cantabria, ETSIIT, Avda. de los Castros s/n, 39005, Santander, SPAIN: (+34)-942201591 : e-mail * : irabienj@unican.esIntroductionLignin derivatives account for a significant fraction of the biorefractory content in thewastewaters coming from the pulp and paper industry. Biological activated sludge processesdo not allow the treatment of biorefreactory organic carbon. Advanced oxidation processes(AOP) such as electrochemical oxidation have been described as an efficient alternative dueto the removal of dissolved organic matter by electro-generated oxidations (1).Lignosulphonate was selected as specific compound to describe the biorefractory fraction ofthe wastewaters. Total Organic Carbon (TOC) will be studied in the effluent.Experimental results and discussionThe Lab-scale electrochemical treatment plant is based on a conventional two-parallelboron-doped diamond (BDD) electrodes flow cell DiaCell 106.101 ® (Adamant Technologies)operated in a batch mode under isothermal conditions and constant flowrate. TOC removalwas studied until 90% reduction was obtained.In order to study the effect of selected variables (initial TOC ([TOC] 0 ), current density (j)and supporting electrolyte concentration ([Na 2 SO 4 ])) in the electrochemical oxidation oflignosulphonate, the experimental design and kinetic modelling shown in table 1 wasperformed. According to experimental TOC time profiles, a first order kinetics was used todescribe experimental results in the form of dimensionless TOC:Table 1. Experimental design and kinetic constants[TOC]Exp. run0 j [Na 2 SO 4 ] k·10 3(mgC·L –1 ) (mA·cm –2 ) (g·L –1 ) (min –1 ) * r 2 k I·10 3(min –1 ) * 2 kr II·10 3I(min -1 ) * 2r II1 150 30 5 3.92±0.29 0.9883.78±0.17 0.989 3.78±0.17 0.9892 150 30 2.5 3.64±0.20 0.9935 450 30 5 2.93±0.15 0.9932.98±0.13 0.988 2.98±0.13 0.9886 450 30 2.5 3.03±0.26 0.9853 150 60 5 4.39±0.22 0.9944.52±0.16 0.9934 150 60 2.5 4.65±0.25 0.9944.42±0.12 0.9917 450 60 5 4.07±0.25 0.9928 450 60 2.5 4.59±0.24 0.994 4.32±0.20 0.989− 10( )TOC· TOC = exp −k·t ∀t≥ 0,*Confidence range=95%297