Biohydrogen production from sugar industry effluents using nickel based electrode materials in microbial electrolysis cell

i n t e r n a t i o n a l j o u r n a l o f h y d r o g e n e n e r g y x x x ( 2 0 1 8 ) 1 e8

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Biohydrogen production from sugar industry effluents using nickel based electrode materials in microbial electrolysis cell Tamilmani Jayabalan, Manickam Matheswaran, Samsudeen Naina Mohammed* Department of Chemical Engineering, National Institute of Technology, Tiruchirappalli, Tamilnadu, 620015, India

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abstract

Article history:

Biohydrogen production from sugar industry effluents in a dual chamber microbial elec-

Received 23 July 2018

trolysis cell (MEC) was investigated in this study. The MEC reactor was operated with

Received in revised form

different effluents as a substrate from cane sugar and raw sugar reprocessing units of sugar

10 September 2018

industry. The biohydrogen production was investigated using different cathode materials

Accepted 26 September 2018

of Nickel plate, Nickel foam, Stainless Steel mesh. The performance of MEC was tested

Available online xxx

based on the production of hydrogen, coloumbic efficiency, hydrogen recovery and COD removal efficiency respectively. The MEC hydrogen productions revealed that cane sugar

Keywords:

effluent was more effective as compared to raw sugar effluent. The experimental results

Microbial Electrolysis Cell

showed that at an applied voltage of 1.0 V, Ni-foam exhibited maximum hydrogen pro-

Hydrogen

duction of 1.59 and 1.43 mmol/L/D in cane sugar and raw sugar effluents respectively,

Sugar industry wastewater

which was about twice than SS-mesh and 1.2 times Ni-plate. This study shows that Ni-

Cathode materials

foam is one of the potential candidate as low cost electrode for improving hydrogen production in MEC technology with the treatment of industrial effluents. © 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Introduction Focuses on energy from waste has become inevitable as of their benefits in reducing large amount of wastes with energy recovery. An increasing attention towards energy recovery from wastewater and simultaneous treatment is rapidly growing in the research arena of wastewater treatment [1]. Hydrogen is potential candidate that has evolved out as better technology platform due to its energy content, lightweight and less polluting nature [2]. Industrial production of hydrogen by steam reforming, metal acid and thermochemical methods involves intricate process influencing high

economy [3]. Hence tremendous development in the biological route of producing hydrogen has paved the way of exploration employing organisms and enzymes such as Bio-photolysis, Microbial electrolysis, Fermentation and Dark-fermentation [4]. Hydrogen production from industrial and domestic wastewater has been assisted by microbiology for improved energy conversion and high yield. Effluents from industries are treated in microbial electrolysis cell (MEC) so that they play an important role as waste bio refinery with beneficiary applications [5]. Microorganisms assisted energy conversion technology has become the trend to face the global crisis for sustenance.

* Corresponding author. Department of Chemical Engineering, National Institute of Technology, Tiruchirappalli, Tamilnadu, 620015, India E-mail address: [email protected] (S. Naina Mohammed). https://doi.org/10.1016/j.ijhydene.2018.09.219 0360-3199/© 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved. Please cite this article in press as: Jayabalan T, et al., Biohydrogen production from sugar industry effluents using nickel based electrode materials in microbial electrolysis cell, International Journal of Hydrogen Energy (2018), https://doi.org/10.1016/j.ijhydene.2018.09.219

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The technological advancement of Bioelectrochemical systems (BES) has evolved as a significant and economic route in terms of generation of hydrogen and other value added products [6]. Various types of BES have been developed in recent years for diverse purpose and are categorized into Microbial Fuel Cell (MFC), Microbial Electrolysis Cell (MEC), Microbial Remediation Cell (MRC), Microbial Desalination Cell (MDC) etc. [7]. The progressive development of the primitive MFC into simple and complex systems for energy generation has led to the rise of other bio-electrochemical systems. An MFC altered bio-electrochemically assisted reactor has paved the way of the various architecture of BESs especially MEC for generation of hydrogen and other value-added products even from the low-grade substrates [8,9]. Many modifications in these systems led to MEC, a BES which is capable of producing hydrogen energy from substrates (chemical energy) when completely devoid of oxygen atmosphere, and this can be influenced by the addition of small voltage to the system [10]. The targeted cathodic reaction is the hydrogen evolution reaction (HER) which has to be achieved below the water electrolysis potential (1.23 V) [11]. The technology has faced a wide assessment of pioneering research in the reactor design, substrates, membrane, catholyte, microorganisms and electrode materials etc., [9]. Use of wastewater in these systems has facilitated their treatment along with generation of energy, making this an energy efficient process rather than dumping into the environment. Many microorganisms reduce or intake very toxic substances like heavy metals and others compounds and yield many value-added products on down streaming The cost and operational savings of a singlechamber MEC are low but the quality of the hydrogen produced is better in dual chamber MEC due to the presence of membrane [12]. The dual chamber MEC technologies are even employed in domestic and combined wastewater systems for restoring energy back from it [13]. Both synthetic and industrial effluents are used for hydrogen production in MEC. Acetate is the most commonly used synthetic substrate in MEC for the microorganisms to easily break it down into Hþ and electrons under favourable conditions [8,12,14,15]. Varieties of wastewater have been explored as substrates in the cell but hydrogen production rate was considerably low when compared with acetate-fed reactors [9]. Recent years, domestic wastewater treatment has been coupled with hydrogen production adhering to this promising technology [16,17]. Industrial effluents, both high grade and low grade, have to be treated with well-established and efficient systems to avoid the environmental issues [18e23]. Sugar industry is considered as an energy sector industry as its end products used effectively. Bagasse after cane crushing is used for power generation coherently and the final molasses is used for distilleries, thus boosting overall energy and economy of the industry [24]. The process wastewater is the only left out that can be treated for recovery of valueadded chemicals, improving the performance of sugar industry [25]. The organic loading rate depends upon the type of process involved whether cane sugar making or raw sugar reprocessing, and infiltration of other waters into the treatment units. Generally, sugar cane from the agricultural field are transported to the yard for cane crushing which is done by

milling operation for cane juice for making sugar. In raw sugar reprocessing, the exported raw sugar (brown in colour) is melted, further reprocessed with addition of chemicals to remove impurities and colour and made to required size as white sugar. Recent studies focus on the cost-effective cathode material for sustainable hydrogen production in order to overcome expensive Pt catalyst [26]. Material development has the major challenge of economic feasibility and minimization of high over-potential losses. Nickel-based materials have proven a better alternative for both cathode and catalyst which exhibit less over-potential for HER [27e31]. Previously the MFC studies had displayed the prospective energy generation in form of current from wastewater from distilleries which are allied industries of sugar manufacturing [32]. Hence in this investigation, the sugar industry effluents, both raw sugar reprocessing wastewater (RSW) and cane sugar industry wastewater (CSW), which are less exploited and also novel substrate with fermentable organics for MEC technology, is used for hydrogen generation. The performance of MEC in terms of hydrogen production rate, cathodic hydrogen recovery, overall hydrogen recovery and COD removal efficiency were investigated by employing nickel based cathode materials including a scrap material for the furtherance of energy, environment and economy. The three cathode materials stainless steel (SS-mesh), Nickel foam (Ni-foam), and nickel scrap plate (Ni-plate) are assessed for the hydrogen production in MEC reactors along with the electrochemical characterization of the nickel-based cathode materials.

Materials and methods Characteristics of wastewater Wastewater was collected from Cane Sugar industry (CSW) and Raw sugar reprocessing industry (RSW) nearby Tiruchirappalli, India. The important characteristics of both effluents were given in Table 1 and possessed brownish yellow colour with less turbidity and foul smell. The wastewaters were stored in the deep freezer and made to 30 ± 2  C prior to use. All the chemicals dipotassium hydrogen phosphate (K2HPO4), Potassium dihydrogen phosphate (KH2PO4), Potassium ferricyanide (K3Fe(CN)6), Sodium hydroxide (NaOH), Sodium chloride (NaCl) and Sulphuric acid (H2SO4) were analytical grade reagent obtained from Merck and directly used without any further purification.

Electrodes SS-mesh (Alfa Aesar), Ni-foam (Qi Jing Trading Co., Ltd, China), and Ni-plate were used as cathode electrodes for hydrogen evolution in MEC. SS-mesh grade304 having 40 openings per inch woven from 0.25 mm (0.01 in) diameter wire and Ni-foam was of 99.8% Ni content with surface density of 380 ± 30 g/m2, Porosity 95%with 0.2e0.6 mm pore diameter were used. Ni-plate was obtained from casting industry having minimum 99% of Ni with commercial grade. Graphite was used as anode material in the reactor setup. The anodes and cathode were cut into rectangular shape of 6  4 cm2.

Please cite this article in press as: Jayabalan T, et al., Biohydrogen production from sugar industry effluents using nickel based electrode materials in microbial electrolysis cell, International Journal of Hydrogen Energy (2018), https://doi.org/10.1016/j.ijhydene.2018.09.219

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Table 1 e Important characteristics of wastewater. Type

pH

COD ppm

TDS ppm

Conductivity mS

Salinity ppm

Resistivity U

CSW RSW

4.5 4.7

4124 6540

2880 4010

266 313

3263 4556

11.9 13.3

MEC construction and operation A MEC reactor with a volume capacity of 250 mL for each chamber was constructed with plexiglass plate of 3 mm thickness separated by proton exchange polymer membrane Nafion-117 (DuPont™, Nafion®) [32]. Membrane pre-treatment was performed with initial boiling in distilled water at 80e90  C in a water bath, then in 5% H2O2 subsequently by 0.5 M H2SO4 for 1 h at 70e80  C and washed and stored in deionized water. A plain graphite electrode used as an anode and SS-mesh, Ni plate and Ni foam as cathode with copper wire acting as the current conductor. The anode and cathode electrode was placed at an equal distance of 1.5 cm from the membrane. The anode and cathode chamber were completely sealed with epoxy sealant to maintain an anaerobic environment and the cathode chamber was connected to gas collection setup. The Applied voltage to the MEC from an adjustable DC power source (LQ6324, Aplab Limited) was connected through copper wire with electrodes. For the loop current, an external resistance of 10 U was connected to measure the current across this resistance and recorded in the Data Acquisition System (LTDAQ-1052, Labtech Electronics Pvt Ltd, Chennai). Hydrogen gas was collected by downward displacement method in fabricated glass unit closed with silicone stopper at top for sample collection using gas tight syringe. The schematic representation of the MEC is shown in Fig. 1. Initial experiments were executed for optimizing the anolyte pH, substrate concentration, catholyte and applied voltage of the system. The batch-cycle operation was executed in all MECs experiments with different catholyte solution and both sugar industry effluents as substrate. Three

catholyte, 50 mmol Phosphate Buffer, 50 mmol Potassium Ferricyanide, and 50 mmol Phosphate Buffer þ50 mmol Potassium Ferricyanide were considered to investigate the maximum hydrogen generation from sugar industry wastewater. Applied voltage varied from 0.2 V to 1.2 V was studied for finding optimum voltage for further studies. By applying optimum voltage to the different cathode electrode for the hydrogen production in the MEC. All experimentations (triplicate) were done in an ambience-controlled room at 30 ± 2  C. The collected gas sample was taken in gas tight syringe for analysis in Gas chromatography intermittently.

Calculations and analyses The parameters pH, Total Dissolved Solids (TDS), Conductivity, Salinity and Resistivity were measured using multiparameter analysis instrument (PCD650, Eutech Instruments). The wastewater Chemical Oxygen Demand (COD) was measured by standard potassium dichromate (close reflux) method using spectrophotometry (Spectroquant TR320, Merck). Gas chromatography (Thermo Fisher Scientific) with thermal conductivity detector (TCD) was used for the gas component analysis where nitrogen gas was deployed as carrier gas for intense identification of peaks of hydrogen. For Electrochemical characterization, cyclic voltammetry (CV) analysis was conducted on a potentiostat (Amteksi, USA) over a potential range of 1.0 V to 1.0 V at a scan rate of 50 mV/s in an electrochemical cell using phosphate buffer solution as an electrolyte. An electrochemical cell consisted of three electrode system in which SS mesh, Ni foam and Ni plate as working electrode, Pt as counter electrode and Ag/AgCl as reference electrode respectively.

Fig. 1 e a) Schematic representation of the MEC reactor and b) Experimental setup. Please cite this article in press as: Jayabalan T, et al., Biohydrogen production from sugar industry effluents using nickel based electrode materials in microbial electrolysis cell, International Journal of Hydrogen Energy (2018), https://doi.org/10.1016/j.ijhydene.2018.09.219

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Hydrogen production rate (HPR)is the parameter to evaluate the hydrogen generation performance of the MEC and can be calculated as: HPR; mmol=L=D ¼

Cumulative Hydrogen productionðmmolÞ Volume of reactorðLÞ x batch Time ðDÞ

(1)

COD removal efficiency was expressed in percentage and calculated COD removal Efficiency;% ¼

DCODðg=lÞ  100 Initial COD ðg=lÞ

(2)

where DCOD is the COD consumption over a batch cycle i.e., the difference between the initial COD and the final COD. Coulombic efficiency (CE) is the ratio of number of moles of hydrogen recovered based on the measured current nCE (mmol) to the theoretical moles of hydrogen production based on COD removal nTH (mmol). CE;% ¼

nCE  100 nTH

(3)

where nCE and nTH were calculated from the Eqs. (4) and (5) respectively. Z

t

I dt nCE ¼

t¼0

(4)

2F

where, I ¼ V/Rex (A) is the current for integration over the time of a batch cycle and Faraday's constant F ¼ 96485 C mol-1. nTH ¼

b  DCOD  Van M

(5)

where Van is volume of anolyte (mL), M is the molecular weight of final electron acceptor, b is number of electrons transferred/mole. Cathodic Hydrogen Recovery (CHR) is the ratio of moles of hydrogen production during a batch cycle nH2 (mmol) to number of moles of hydrogen recovered based on the measured current nCE (mmol). CHR;% ¼

nH2  100 nCE

(6)

Overall hydrogen recovery is the product of coloumbic efficiency CE and the cathodic hydrogen recovery CHR. It is calculated as: OHR;% ¼ CE  CHR ¼

nH2  100 nTH

effluents. The effect of electrolyte pH and substrate concentration were investigated using three different cathodes for the hydrogen production. The choice of the catholyte was based on the HPR initial studies, which ruled out the oxidizing agent Potassium ferricyanide against phosphate buffer by a margin of 33.3%. This is because phosphate buffer was readily giving electrons to protons to combine and form hydrogen by buffer action [33]. The cathode buffer solution pH adjusted to 7 for further studies as neutral pH relatively enables more proton exchange for high production rate [34]. The effect of anolyte pH was investigated from the effluent pH 4.5 to 7 for both CSW and RSW. Fig. 2 shows that the highest HPR was obtained at pH 6.5 and the lowest HPR was acquired at initial pH [35]. Substrate concentration was varied from 10 to 100%, which revealed 100% substrate concentration was able to achieve the higher production. From these results, MEC reactor were operated using the two effluents of 100% concentration and pH 6.5 as anolyte and phosphate buffer of pH 7 as catholyte for three different cathodes.

Electrochemical characteristics of cathodes Electrochemical Characterization of the material was done to study the nature of the three material employed in the enhancement of the bio-hydrogen production from the realtime wastewater. It was necessary to characterize the Nickel scrap material used as electrode along with Ni-foam and SS mesh as to illustrate its behaviour deviation having much significance in HER. To apprehend the performance changes within the three cathodes, cyclic voltammetry on electrodes was used to characterize the electrochemical properties of these materials. Accounting SS cathodes, it has been reported with increased HER catalytic activity due to the occurrence of SS corrosion [21,36]. Considering Nickel based materials, they have been reported with better catalytic activities for hydrogen evolution reaction owing to the electrochemical corrosion at maintained cathodic potential [35e37]. Fig. 3 illustrates the cyclic voltammogram of the three cathodes obtained revealing the predominant behaviour difference of SS mesh from Ni cathodes. The voltammogram clearly indicates the oxidation peaks of three electrode materials. These peaks

(7)

Energy recovery (sE) based on the electrical input is calculated as Eq. (8). sE ¼

nH2 ðmmolÞ  Energy content of hydrogen ðJ=mmolÞ  100 Electrical Input ðJÞ (8)

Results & discussion Effect of electrolyte for the hydrogen production The catholyte and anolyte conditions were investigated for the production of hydrogen in the MEC using sugar industry

Fig. 2 e Effect of pH on HPR for initial tests.

Please cite this article in press as: Jayabalan T, et al., Biohydrogen production from sugar industry effluents using nickel based electrode materials in microbial electrolysis cell, International Journal of Hydrogen Energy (2018), https://doi.org/10.1016/j.ijhydene.2018.09.219

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Fig. 3 e Cyclic voltammetry of three different cathodes against counter electrode (platinum plate), and reference electrode (Ag/AgCl).

were more evident in SS mesh and Ni foam when compared to Ni-plate. The increased slope of Ni cathodes apart from SS mesh was a clear indication of the excellent performance of them towards effective hydrogen production by allowing a higher current at the same potential. The peak cathodic current incurred by Ni foam was thrice the SS mesh and double of Ni scrap plate at the scan voltage. At the corresponding potential of 1.0 V, the current densities observed were 11.23 A/ m2, 4.56 A/m2, 8.144 A/m2 for Ni foam, SS mesh and Ni plate respectively. This behaviour relates to the current increment with the hydrogen production performance by the cathode materials. Less over potential losses of the material are responsible for more effective hydrogen evolution by catalytic activity due to smaller onset potential [38]. Compared to SS cathode, Ni foam proved a better candidature in terms of the onset potential rather than a plate with less porosity. Electrochemical characterization of material has directly exposed

Fig. 4 e COD removal efficiency.

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Fig. 5 e Current density of different cathodes in MECs at applied voltage 1.0 V with phosphate buffer solution.

the individual competency of material in the substantial treatment of the industrial effluents.

Substrate degradation From the initial studies, the MEC was operated with catholyte of phosphate buffer (pH 7) and anolyte of two effluents (pH 6.5) at an applied voltage of 1.0 V with help of in-situ organisms. Substrate degradation by microorganisms had been reported in terms of COD removal, as it is obvious that hydrogen production is by breaking down of the organic load in the wastewater. COD removal efficiency was 8e10% higher for CSW than RSW and though COD of RSW was higher, which might be due to the chemicals used in reprocessing not of the organic content as from the cane crushing. Among the three cathodes, removal efficiency was increasing in the order of SS mesh < Ni plate < Ni foam as shown in Fig. 4. In RSW COD removal by Ni-foam was 40.1%, which higher than Ni plate

Fig. 6 e Cumulative HPR Vs three cathodes materials of this study in both effluents.

Please cite this article in press as: Jayabalan T, et al., Biohydrogen production from sugar industry effluents using nickel based electrode materials in microbial electrolysis cell, International Journal of Hydrogen Energy (2018), https://doi.org/10.1016/j.ijhydene.2018.09.219

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Table 2 e Summary of results from MECs at the applied voltage 1.0 V for the three cathodes in the two sugar industrial effluents. Substrate

Cathode

COD removal (%)

CE (%)

CHR (%)

OHR (%)

HPR (mmol/L/D)

sE (%)

CSW

SS mesh Ni plate Ni foam SS mesh Ni plate Ni foam

40.59 48.11 49.56 30.43 38.99 40.06

45.11 54.52 59.18 44.09 54.67 56.64

13.86 15.73 16.88 8.95 9.39 12.35

6.25 8.57 9.99 3.95 5.13 6.99

0.817 1.329 1.594 0.613 1.022 1.431

121.26 124.49 126.76 113.54 114.54 119.20

RSW

and SS mesh by 1.11% and 10.37% respectively. While Ni foam exhibited 49.5% removal in CSW, overruling SS mesh by 10% and Ni plate by 1.43%. The removal efficiency was about 40e60% because sugar industry effluent is a low-grade substrate and in-situ organisms were only used for hydrogen production. The substrate degradation occurred in both wastewater employing three cathodes were analogous with the current density and the hydrogen production. Fig. 5 shows the current density (A/m2) of three cathodes in MECs with two effluents and phosphate buffer at the applied voltage of 1.0 V. It had been reported that treatment efficiency with respect COD removal in wastewater of similar industries like food producing industries using SS cathodes were limited to 49% [21]. Even in Dual chamber concentric tubular MEC using acetate substrate the COD reduction was in the range of 12e32% at applied voltages of 0.6 and 0.85 V [35]. These results were similar to other low-grade substrates like domestic wastewater and above 90% removal could be achieved when employing target specific microorganisms [11,15,22].

Hydrogen production rate In consistence to the voltammetry tests, Ni-foam attained highest HPR among the three electrodes in both CSW and RSW. Analogous to the start-up experiments HPR increased from varying applied voltage from 0.2 to 1.0 V linearly and decreased for 1.1 and 1.2 V. The maximum production of hydrogen was obtained at 1.0 V. Both effluents portrayed the incremental HPR when SS cathodes were changed to Ni plate

70

60

CE CHR OHR

CE,CHR & OHR, %

50 40 30

Studies on performance of MEC Performance of the MEC system on the two industrial effluents was expressed in terms of Coulombic efficiency (CE), Cathodic Hydrogen Recovery (CHR), Overall Hydrogen Recovery (OHR) and Energy recovery (ER) are shown in Table 2. Coulombic Efficiency of both systems was in the range of 45% for SS mesh to 60% of Ni foam based on the current measurement over time and comparable with literature reported values [10,13,40e43]. From Fig. 7, Ni foam displayed 3.5% and 21% higher than Ni plate & SS mesh in RSW, while 7.8% and 23.8% higher than Ni plate & SS mesh in CSW correspondingly. It was evident that CHR was only 12.4% and 16.9% even for the better cathode (Ni foam) due to the use of the low-grade substrates as well as low yield due to dual chamber technology with membrane mediator. OHR obtained was 3e10% in both substrates indicating the hydrogen recoveries in low organic loading were similar industrial effluents [10]. There was no obvious difference in corresponding hydrogen recoveries between the two effluents. Methane inhibition due to higher applied voltage (1.0 V) and selective membrane in the dual chamber technology have attributed to the yield and the purity of hydrogen produced [28].

Conclusion

20 10 0

and Ni foam cathodes in consequent batch cycles. Ni foam depicted the maximum HPR in CSW, which was 57.2% higher than SS mesh and 28.6% higher than Ni scrap for CSW. While, and Ni foam exhibited 48.7% higher than SS mesh and 16.7% higher than Ni plate for RSW respectively (see Fig. 6). Similar HPR of 1.71 mmol/L/D had been reported from lignocellulose saccharification and fermentation in same capacity MEC at 30  C and pH 6.5, comparable due to change contents of reducing sugar [34]. Generally industries effluents in MEC had shown low yield when compared to the acetate or nonfermentable organics like glucose, acetic acid, lactic acid etc. [39]. The hydrogen production obtained in this study was tabulated in Table 2.

SS mesh Ni plate Ni foam SS mesh Ni plate Ni foam CSW

RSW

Fig. 7 e Performance of three cathodes in both effluents.

This study investigated the bio-hydrogen production from two types of sugar industrial effluents in dual chamber MEC system using three different cathodes. The results obtained revealed that cane sugar effluent had superior performance of hydrogen production than raw sugar effluents. Also, the parameters such as anolyte pH, effluent concentration, applied voltage along with a choice of catholyte and all their effects were studied for better biohydrogen production in

Please cite this article in press as: Jayabalan T, et al., Biohydrogen production from sugar industry effluents using nickel based electrode materials in microbial electrolysis cell, International Journal of Hydrogen Energy (2018), https://doi.org/10.1016/j.ijhydene.2018.09.219

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the MEC system. On evaluation of three electrodes in the MEC system using both effluents, the performance of Ni foam was much better than other cathodes. At an applied voltage of 1.0 V, the maximal hydrogen production rates were 1.59 and 1.43 mmol/L/D for CSW and RSW by Ni-foam. Analogous with electrochemical studies, Ni plate exhibited many phenomenal characteristics similar but Ni foam portrayed the better outcomes due to its structure and highly porous nature. The high performance of biohydrogen production by Ni foam superior to Ni plate and SS mesh in MEC system was demonstrated with the COD removal, the current measurements over time, coloumbic efficiency, cathodic hydrogen recovery, overall hydrogen recovery and energy efficiency. Substrate degradation could be improved if the target specific microorganisms are utilized in the system. Thus, Sugar effluents could be attributed in hydrogen production using MEC system by employing Ni foam, and this low cost and high efficient cathode promotes this technology for sustainable hydrogen production from various industrial effluents.

Acknowledgment The authors thank to Ms. Nivedhini Iswarya C and Mrs. Pramila M, Research Scholars, Department of Chemical Engineering, NIT, Tiruchirappalli for helping to carry out CV and Gas Chromatography analysis. The corresponding author greatly acknowledges Dr. Mahendra Sunkara and Dr. Jagannadh Satyavolu, Conn Centre for Renewable Energy Research, University of Louisville, KY, USA for valuable research discussions. The corresponding author acknowledges the Department of Biotechnology, India, Indo-US Science and Technology Forum (IUSSTF) for financial support to the BACER Award for fellowship programme.

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Please cite this article in press as: Jayabalan T, et al., Biohydrogen production from sugar industry effluents using nickel based electrode materials in microbial electrolysis cell, International Journal of Hydrogen Energy (2018), https://doi.org/10.1016/j.ijhydene.2018.09.219

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Please cite this article in press as: Jayabalan T, et al., Biohydrogen production from sugar industry effluents using nickel based electrode materials in microbial electrolysis cell, International Journal of Hydrogen Energy (2018), https://doi.org/10.1016/j.ijhydene.2018.09.219