title: Electrochemical treatment of evaporated residue of soak liquor generated from leather industry.
abstract: The organic and suspended solids present in soak liquor, generated from leather industry, demands treatment. The soak liquor is being segregated and evaporated in solar evaporation pans/multiple effect evaporator due to non availability of viable technology for its treatment. The residue left behind in the pans/evaporator does not carry any reuse value and also faces disposal threat due to the presence of high concentration of sodium chloride, organic and bacterial impurities. In the present investigation, the aqueous evaporated residue of soak liquor (ERSL) was treated by electrochemical oxidation. Graphite/graphite and SS304/graphite systems were used in electrochemical oxidation of organics in ERSL. Among these, graphite/graphite system was found to be effective over SS304/graphite system. Hence, the optimised conditions for the electrochemical oxidation of organics in ERSL using graphite/graphite system was evaluated by response surface methodology (RSM). The mass transport coefficient (km) was calculated based on pseudo-first order rate kinetics for both the electrode systems (graphite/graphite and SS304/graphite). The thermodynamic properties illustrated the electrochemical oxidation was exothermic and non-spontaneous in nature. The calculated specific energy consumption at the optimum current density of 50 mA cm(-2) was 0.41 kWh m(-3) for the removal of COD and 2.57 kWh m(-3) for the removal of TKN.
authors.affiliation: Environmental Technology Division, Council of Scientific & Industrial Research - Central Leather Research Institute, Adyar, Chennai - 20, India.
authors.forename: R
authors.initials: R
authors.lastname: Boopathy
authors.forename: G
authors.initials: G
authors.lastname: Sekaran
mesh_terms: D002713:Chlorine / Q000737:chemistry; D004563:Electrochemistry / Q000379:methods*; D004566:Electrodes; D004867:Equipment Design; D006108:Graphite / Q000737:chemistry; D007220:Industrial Waste; D008962:Models, Theoretical; D009930:Organic Chemicals; D010100:Oxygen / Q000737:chemistry; D012965:Sodium Chloride / Q000737:chemistry; D013633:Tanning; D013696:Temperature; D014865:Waste Disposal, Fluid / Q000379:methods; D014874:Water Pollutants, Chemical; D018508:Water Purification / Q000379:methods
chemical_list: D007220:Industrial Waste; D009930:Organic Chemicals; D014874:Water Pollutants, Chemical; D012965:Sodium Chloride; D002713:Chlorine; D006108:Graphite; D010100:Oxygen
keywords: A; ANOVA; APHA; American public health association; C; CCD; COD; COD(0) and COD(t); ERSL; Electrochemical oxidation; Evaporated residue; F; Faraday constant, 96,487 (Cmol(−1)); I; K(e); R(2); RSM; Response surface methodology; S(V); SS; Salt laden wastewater; Soak liquor; T; TKN; TKN(0) and TKN(t); V; VDS; W; [COD](opt); analysis of variance; are the chemical oxygen demand at initial and at time ‘t’ min; are the total Kjeldahl nitrogen at initial and at time ‘t’ min; average cell potential (V); average mass transfer coefficient (ms(−1)); central composite design; change in Gibbs free energy (Jmol(−1)); change in enthalpy (Jmol(−1)); change in entropy (Jmol(−1)K); chemical oxygen demand; concentration of COD at optimum time (120min); concentration of ERSL % (w/v); current (A); current density and limiting current density (mAcm(−2)); electrochemical oxidation time (min); electrode area (m(2)); equilibrium constant; evaporated residue of soak liquor; j and j(L); k(mCOD)/k(m(TKN)); regression coefficient; response surface methodology; sample volume (L); specific energy consumption (kWhkg(−1) of COD/TKN); stainless steel; t(eco); temperature (K); total Kjeldahl nitrogen; volatile dissolved solids; ΔG; ΔH; ΔS