Red mud & graphene oxide blend as an effective coagulant and adsorbent for the treatment of waste water from various industries

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A series of blends consisting of Red mud(RM) varying from 1.5 to 3 g and Graphene oxide(GO) varying from 0 to 1.5 g to give a total of 3g were prepared.

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Nội dung Text: Red mud & graphene oxide blend as an effective coagulant and adsorbent for the treatment of waste water from various industries

International Journal of Mechanical Engineering and Technology (IJMET) Volume 10, Issue 03, March 2019, pp. 331-340. Article ID: IJMET_10_03_034 Available online at http://www.iaeme.com/ijmet/issues.asp?JType=IJMET&VType=10&IType=3 ISSN Print: 0976-6340 and ISSN Online: 0976-6359 © IAEME Publication Scopus Indexed RED MUD & GRAPHENE OXIDE BLEND AS AN EFFECTIVE COAGULANT AND ADSORBENT FOR THE TREATMENT OF WASTE WATER FROM VARIOUS INDUSTRIES K. Gouru Naidu Department of Basic Science & Humanities (BS&H), GMR Institute of Technology, Rajam- 532127, A.P., India K. Venkata Krishna Department of Chemical Engineering, GMR Institute of Technology, Rajam-532127, A.P., India K. Koteswara Rao Department of Basic Science & Humanities (BS&H), GMR Institute of Technology, Rajam- 532127, A.P., India ABSTRACT A series of blends consisting of Red mud(RM) varying from 1.5 to 3 g and Graphene oxide(GO) varying from 0 to 1.5 g to give a total of 3g were prepared. They are used as adsorbents in the treatment of waste water samples from few industries, for effective removal of phosphates, phenols, heavy metals and dyes. The best blend compositions for removal of Phosphates, Heavy metals & Phenols, Dyes were 2.5:0.5; 2.75:0.25; 2.1:0.9 respectively. The percentage removal of Phosphates & Nickel was 100 % while the removal of Zn varied from 58 to 68 % for the refinery samples studied. The contact time required for 95 % removal of phenols was just 4 hrs. In the studied dyes, Congo red showed maximum adsorption of 10 mg/g. Key words: Red Mud, Graphene Oxide, Phosphate, Heavy metals, Phenol, Dyes Cite this Article K. Gouru Naidu, K. Venkata Krishna and K. Koteswara Rao, Red Mud & Graphene Oxide Blend as an Effective Coagulant And Adsorbent For the Treatment of Waste Water From Various Industries, International Journal of Mechanical Engineering and Technology, 10(3), 2019, pp. 331-340. http://www.iaeme.com/IJMET/issues.asp?JType=IJMET&VType=10&IType=3 http://www.iaeme.com/IJMET/index.asp 331 editor@iaeme.com
Red Mud & Graphene Oxide Blend as an Effective Coagulant and Adsorbent For the Treatment of Waste Water From Various Industries 1. INTRODUCTION The industrial wastewatersusually have lot of variation in both their flow rates and the intensity of pollution. So, it is almost impossible to assign any fixed values to their constituents. In general, industrial wastewaters do contain some suspended, colloidal and dissolved (mineral and organic) solids. Apart from being either excessively acidic or alkaline sometimes they may even contain high or low concentrations ofcolored matter, inert organic or toxic materials and possiblypathogenic bacteria [1]. These wastes may be discharged into the sewage system,at times, and therefore necessitate pretreat before releasing it to the municipal system or it isnecessary to a fully treat when the wastes are discharged directly to surface orground waters. The most significant environmental problem and threat to public health in both rural andurban India is inadequate access to clean drinking water and sanitation facilities [2]. Almostall the surface water sources are contaminated to some extent by organic pollutants andbacterial contamination and make them unfit for human consumption unless disinfected[3].The urban India has become a massive and perhaps a frightening reality as far as wastemanagement is concerned. This country can no longer afford to allow urban areasconstituting cities and towns of varying magnitude to take care of them; they need the fulland undivided attention of our planners and decision makers for protection of environment,aquatic resources and ultimately for better management of health aspects[4]. An estimated 38354 millionlitres per day (MLD) sewage is generated in major cities of India,but the sewage treatment capacity is only of 11786 MLD. Similarly, only 60% of industrial wastewater, mostly large scale industries, is treated[5].In developing countries like India, the problems associated with wastewater reuse arise fromits lack of treatment. The challenge thus is to find such low-cost, low-tech, user friendlymethods, which on one hand avoid threatening our substantial wastewater dependentlivelihoods and on the other hand protect degradation of our valuable natural resources. Theuse of constructed wetlands is now being recognized as an efficient technology forwastewater treatment. Compared to the conventional treatment systems, constructed wetlandsneed lesser material and energy, are easily operated, have no sludge disposal problems andcan be maintained by untrained personnel[6]. Red Mud (RM) is a residue of the aluminium industry rejected during the alkaline extraction of alumina from bauxite by the Bayer or sintering process [7]. Many efforts are being made globally to find suitable uses for red mud. Some researchers focused on the application of red mud in wastewater treatment [8].Red mud is composed of a mixture of solid and metallic oxides. The red colour arises from iron oxides, which comprise up to 60% of the mass of the red mud [8]. The mud is highly basic with a pH ranging from 10 to 13. In addition to iron, the other dominant components include silica, unleached residual aluminium, and titanium oxide.Graphite oxides(GO) demonstrate considerable variations of properties depending on degreeof oxidation and synthesis method.Due to Graphene oxide’s large theoretical specific surface area and hydrophobic nature it canbe utilized for the adsorption of organic pollutants to environmental pollution cleanup [9]. The coagulants produced from Red Mud with suitable treatment were used for heavy metal and turbidity removal from industrial wastewaters [10]. Red Mud when activated by acid treatment and neutralization, i.e. activated Red Mud (ARM) was found to have better sorption of Cu than ferric chloride and polyaluminum chloride (PAC) in terms of cost and solid waste volume [11]. On the other hand, Graphene Oxide (GO) is also used either alone or in combination with other adsorbents for waste water treatment [12]. A blend of Red Mud & Graphene Oxide is not reported till now in the waste water treatment. So in this work, we http://www.iaeme.com/IJMET/index.asp 332 editor@iaeme.com
K. Gouru Naidu, K. Venkata Krishna and K. Koteswara Rao have explored the application of RM & GO composite, especially for removal of Phosphates, Heavy metals, Phenols and Dyes in the waste waters of two oil refineries, one pharmaceutical industry and one Fertilizer industry. 2. EXPERIMENTAL METHODS In the experimental studies, a series of Red Mud and Graphene Oxide blends were taken to study the efficiency of them for treating the wastewater samples obtained from different industries. Initially the Red Mud has been activated by using a standard procedure[13]. Graphene Oxide fine particles have also been prepared by using another standard procedure[14]. (i) Activation of Red Mud: 100gms of Red Mud was taken into a beaker for the activation.Activation of Red Mud was carried out by treating it with H2SO4(30%wt solid/liquid, ratio 1:5) with a contact time of 9 hrs. After partial dissolution of RM at room temperature of 250C, the resulting suspension was centrifuged and the leftover mud was neutralized [15]. Then by slow mixing of NaOH to the solution, a pH of 8 is reached and we get a gel like state. (ii) Synthesis of Graphene Oxide: GO was prepared according to the modified Hummer method. In detail, 10g ofgraphite and 5g of NaNO3 were mixed with 216mL H2SO4 and 24mL H3PO4 and stirredin an ice bath for 10min[16]. Next, 30g of KMnO4 was slowly added so that thetemperature of the mixture remained below 5°C. The suspension was then reacted for 2h inan ice bath and stirred for 60min before again stirring it in a 40°C water bath for60min. The temperature of the mixture was adjusted to a constant 98°C for 60min whilewater was added continuously. Deionized water was further added so that the volume of thesuspension was 800mL. 30mL of H2O2 was added after 5min. The reaction product wascentrifuged and washed with deionized water and 5% HCl solution repeatedly[17]. Finally,the product was dried at 80°C. Effluentswere collected from different industries (Refinery 1, Refinery 2, Pharmaceutical industry, Fertilizer industry) which contain organic compounds, heavy metals, anions to test the efficiency of Red Mud (RM) and Graphene-Oxide (GO) blend at different compositions. This blend is also used to remove colour from different dye solutions (Congo Red, Methylene Blue, Para rosaniline and malachite green).Treatment of effluent is done by the following procedure: (iii) Effluent treatment: 100ml of effluent was taken in three conical flasks and mixed with the blend of RM and GO having different compositions. The mixture was shaken at 200rpm for 1hr. Then themixture was allowed for settling for 1hr, when the sludge got settled it was removed. Theacquired solution was used for further treatment i.e. for extraction of metals, phenols andphosphates.75ml of the above treated solution was taken for extraction of metals, 5ml is used forphenol test and 10ml for phosphate test[18 - 20]. The above procedure was repeated for different effluents and also for different shaking times (2& 3hrs). After treating the samples with the blends prepared, the filterate is analyzed for (i) phosphates by spectrophotometry (ii) heavy metals by AAS (Atomic Absorption Spectroscopy) (iii) phenol by spectrophotometry and (iv) dyes - congo red, methyleneblue, malachite green, para- rosaniline, by spectrophotometry. 3. RESULTS AND DISCUSSION: The activated Red Mud, prepared as per the procedure given above, is shown in Figure 1a and appears brown in colour. The Graphene Oxide obtained by following the modified Hummer’s method after final processing is shown in Figure 1b and is black in colour. http://www.iaeme.com/IJMET/index.asp 333 editor@iaeme.com
Red Mud & Graphene Oxide Blend as an Effective Coagulant and Adsorbent For the Treatment of Waste Water From Various Industries Figure 1a Figure 1b The effluents were initially tested and then treated with RM & GO blend at different compositions and their experimental results (RM-2.5 & GO-0.5) are tabulated as below. Table 1: Characteristics of initial effluents from different industries: Effluent Source Pharmaceutical Fertilizer Refinery 1 Refinery 2 Characteristics Industry Industry pH before 6.9 7.2 6.0 2.31 7.0 6.0 6.5 7.0 after Turbidity before 33.8 13.8 31.2 7.5 1.7 1.2 1.1 2.6 after Brown, traces of Yellowish clear Black, pungent Greenish, with rotten Colour, Odour oil droplets, heavy liquor with high smell smell pungent smell phosphate content The pH of the effluents before and after treatment with RM-GO blends remained in the range 6-7.2 except for the Fertilizer industry effluent whose initial pH was 2.31 and reached 7.0 after treatment with RM-GO blend. This could be understood as Red-Mud is originally known to be basic and hence neutralizes the effluent to pH 7.0. However, the turbidity of all the effluents reduced drastically after treatment with RM-GO blend. 3.1. Removal of phosphates: Different blends of Red Mud &Graphene Oxide were used to test the adsorption efficiency ofphosphates from fertilizer industry effluent. According to the experimental results the blendof RM-2.5, GO-0.5 was proved to be the best ratio of adsorbents in the adsorption of phosphates. http://www.iaeme.com/IJMET/index.asp 334 editor@iaeme.com
K. Gouru Naidu, K. Venkata Krishna and K. Koteswara Rao Figure 2 Shiao and Akashi et al [21] first reported an investigation of phosphate removal from aqueous solution using ARM treated with hydrochloric acid. It was found that the ARM exhibited higher adsorption capacity than raw red mud. Theratio of acid volume to red mud weight influenced the adsorption capacity. Huang et al [22] conducted an investigation of phosphate adsorption using red mud from Australia. The red mud sample was treated by different methods such as acid treatment using HNO3 and HCl (RM-HNO3 and RM-HCl) and combination of acid and heat treatment at 700 0 C (RM-HNO3-700 and RM-HCl-700). Mohanty et al. (2004) [23] used sulfuric acid to treat red mud to adsorb phosphorus from dilute aqueous solution. Experiments were carried out in aqueous as well as buffer media to obtain optimum conditions like contact time, pH, adsorbent dose, adsorbate concentration, andtemperature. The pH value of 4.5 was found to be optimum for maximum removal. 3.2. Removal of heavy metals: Different blends of Graphene Oxide and Red Mud were used to test the adsorption efficiency ofheavy metals from refinery, pharmaceutical effluents. Zinc and Nickel metals were analyzedwith different blends of Graphene Oxide and Red Mud. According to the experimental resultsthe blend of composition RM-2.75&GO-0.25, showed highest percentage removalfor Zinc from the effluents of Refinery 1 & 2 (Table 2). In the removal of Nickel, the same blend composition could remove upto 100 % from the effluents of Refinery 1 & 2 as well as from Pharmaceutical industry effluent (Table 3). Table 2: Removal of Zinc Blend Initial conc. of Conc. of metal after Effluent Source % Removal composition metal (ppm) treatment (ppm) RM- 3.0 Refinery 1 3.852 1.928 49.95 GO- 0.0 RM- 2.75 3.852 1.587 58.87 GO- 0.25 RM- 2.50 3.852 2.98 22.63 GO- 0.50 RM- 3.0 Refinery 2 2.102 0.700 64.97 GO- 0.0 RM- 2.75 1.905 0.635 68.25 GO- 0.25 RM- 2.50 2.008 1.673 16.25 GO- 0.50 http://www.iaeme.com/IJMET/index.asp 335 editor@iaeme.com
Red Mud & Graphene Oxide Blend as an Effective Coagulant and Adsorbent For the Treatment of Waste Water From Various Industries Table 3: Removal of Nickel Blend Initial conc. of Conc. of metal after Effluent Source % Removal composition metal (ppm) treatment (ppm) RM- 3.0 Refinery 1 0.716 0 100 GO- 0.0 RM- 2.75 0.716 0 100 GO- 0.25 RM- 2.50 0.716 0 100 GO- 0.50 RM- 3.0 Refinery 2 0.294 0 100 GO- 0.0 RM- 2.75 0.294 0 100 GO- 0.25 RM- 2.50 0.294 0 100 GO- 0.50 Pharmaceutical RM- 3.0 0.095 0.009 93.68 Industry GO- 0.0 RM- 2.75 0.095 0 100 GO- 0.25 RM- 2.50 0.095 0 100 GO- 0.50 Gupta and Sharma (2002)[24] also tested an ARM in batch and column operations for theremoval of cadmium and zinc from aqueous solutions. The red mud was treated by H2O2 andthen heat-treated at 500 0C. The removal of Cd2+ and Zn2+ was almost complete at lowconcentrations, while it was 60–65% at higher concentrations at optimum pH values of 4.0and 5.0, respectively, with 10 g of adsorbent in an 8–10 h equilibration time. Santona et al.[25] (2006)reported an investigation of heavy metal adsorption (such as Pb ,Cd2+ and Zn2+) on non-treated (RMn) and acid-treated red muds[26]. The results 2+ showedthat the RMn adsorption capacity for the three heavy metals was Zn2+> Pb2+> Cd2+, whichagrees with other research works. Acid treatment with HCl decreased the red mud’s capacityto adsorb the heavy metals by 30%, which is quite different from other investigations. Zoumis et al.[27] (2000)conducted an investigation of remediation of mine waters containingheavy metals using industrial wastes (fly ash, red mud scale arrears), natural wastes (e.g., treebark), and relatively cheap natural products (bentonite, zeolites) as active barrier systems. Flyash and red mud presented the best results for the removal of Zn, Cd, Ni, and Mn. 3.3. Removal of Phenol: Different blends of Red Mud and Graphene Oxide were used to test the adsorption efficiency of phenols from refinery effluents. Refinery1 consisting of large amount of phenol traces are found to have phenol (about 5 ppm) beyond the standard limits of around 0.2ppm. The contact time was varied with different blends at different time intervals and the results were predicted. According to the experimental results, at 4 hrs contact time the RM-2.75 gm & GO-0.25 gm blend shows the optimum adsorption rate. http://www.iaeme.com/IJMET/index.asp 336 editor@iaeme.com
K. Gouru Naidu, K. Venkata Krishna and K. Koteswara Rao Rui Hu [28], studied the efficient removal of phenol and aniline from aqueous solutions using graphene oxide/polypyrrole composites. 3.4. Removal of dyes: Red Mud and Graphene Oxide blends were used for adsorption of different dyes (Congo red, methylene blue, malachite green, para-rosaniline) by having the contact time of 10 mins between the blend & dye (Figure 4a). The experimental results have shown that the blends with composition RM-2.1 & GO-0.9 have maximum adsorption rate for the above dyes (Figure 4b). Figure 4a Figure 4b In the past years, several investigations have been carried out toexplore the applicability of red mud for dye removal from wastewater. Namasivayam and Arasi[29] first reported an investigation using red mud for dyeadsorption in aqueous solution. They investigated Congo red (an anionic dye) adsorptionkinetics and isotherms and found that adsorption followed the first-order rateexpression and that the equilibrium adsorption data obeyed both the Langmuir and Freundlich isotherms. The adsorption capacity of the red mud for the dye was 4.05 mg/g. Theyproposed that the mechanism of adsorption was mostly ion exchange. Arias et al. [30] performed a study of methylene blue adsorption on red mud usingboth batch and column techniques and observed two kinetic processes: first a rapid processfollowed by a slow kinetic reaction. The maximum adsorption was 0.74 mg/gfor a reaction time of 192 hours. Gupta et al. [31] studied the removal of some basic dyes, Rhodamine B, fast green, and methylene blue, from wastewater using H2O2-activated redmud. In the batch experiments, the removal efficiencies of Rhodamine B, fast green, andmethylene blue on this adsorbent were http://www.iaeme.com/IJMET/index.asp 337 editor@iaeme.com
Red Mud & Graphene Oxide Blend as an Effective Coagulant and Adsorbent For the Treatment of Waste Water From Various Industries 92.5%, 94.0%, and 75.0%, respectively. Theadsorption was found to be exothermic for the three dyes. Wang et al. [32] investigated the heat and acid treatments of fly ash and red mud on atypical basic dye removal, methylene blue, from aqueous solution. It was found that fly ashgenerally showed higher adsorption capacity than red mud. The raw redmud showed adsorption capacity of 7.8 – 10.6 mol/g and the adsorption was increased with increasing pH. Heat and acid treatment reduced the adsorption capacity due to thereduction of some organics and hydroxyl groups by thermal decomposition and neutralizationof hydroxide ions on the basic surface of red mud. For red mud, adsorption of methylene blue was an endothermic reaction with H of 10.8 kJ/mol. Recently, Tor and Cengelog lu [33] reported a study of removing Congo red, an anionicdye, from water by using acid-activated red mud. It was found that sufficient time to attainequilibrium was 90 min. The Langmuir isotherm was the best-fit adsorption isotherm modelfor the experimental data.In the above investigations, red mud has been only applied to remove two typesof dyes, anionic and basic dyes. The results indicate that physical and chemical treatments ofred mud will significantly influence the adsorption capacity. Acid treatment will result inenhancement of anionic dye adsorption but decrease the basic dye adsorption. 4. CONCLUSIONS The present work has identified that Red mud(RM) & Graphene oxide(GO) and blend is a very effective adsorbent for the treatment of waste water as compared to the earlier reports for removal of phosphates, phenols, heavy metals, dyes. Earlier methods require long time for removal of the parameters under study while this method could effectively remove from a minimum of 10 min (for Dyes) to maximum 4 hrs (for Phenols). The blend of RM-GO with 2.75:0.25 composition exhibited effective removal of phenols present in the effluent samples. With regard to dyes, the maximum adsorption of Congo red was 4.05 mg/g in earlier literature but in this study we have obtained an adsorption rate of 10 mg/g. Heavy metals like Zn & Ni from both the refinery samples were removed upto 68 % and 100 % respectively, by using the optimum RM-GO blend composition of 2.75:0.25. In conclusion, this coagulant is comparatively cost effective (as one of it is a waste material) and is used to treat effluents from various industries. REFERENCES: [1] J.W. Choi, S.Y. Lee, K.Y. Park, K.B. Lee, D.J. Kim, S.H. Lee, Investigation of phosphorous removal from wastewater through ion exchange of mesostructure, Desalination 266 (2011) 281-285. [2] Y.H. Song, P. Yuan, B. Zheng, J. Peng, F. Yuan, Y. Gao, Nutrients removal and recoveryby crystallization of magnesium ammonium phosphate from synthetic swine wastewater,Chemosphere 69 (2007) 319-324. [3] Y.H. Song, D. Donnert, U. Berg, P.G. Weidler, R. Nueesch, Seed selections for crystallization of calcium phosphate for phosphorus recovery, J. Environ. Sci. 19 (2007)591-595. [4] Y.H. Song, P.G. Weidler, U. Berg, R. Nueesch, D. Donnert, Calcite-seeded crystallization of calcium phosphate for phosphorus recovery, Chemosphere 63 (2006)236-243. [5] J. Gao, Z. Xiong, J. Zhang, W. Zhang, F.O. Mba, Phosphorus removal from water of eutrophic Lake Donghu by five submerged macrophytes, Desalination 242 (2009) 193- 204. http://www.iaeme.com/IJMET/index.asp 338 editor@iaeme.com
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