PRODUCTION OF NANO-CARBON SHEETS & TUBES FROM THE EXHAUST PIPES IN INDUSTRIES
INTRODUCTION CARBON NANOTUBES(CNTs) ARE ALLOTROPES OF CARBON WITH A CYLINDRICAL NANOSTRUCTURE. THESE CYLINDRICAL CARBON MOLECULES HAVE NOVEL PROPERTIES THAT MAKE THEM POTENTIALLY USEFUL IN MANY APPLICATIONS IN NANOTECHNOLOGY, ELECTRONICS, OPTICS AND OTHER FIELDS OF MATERIALS SCIENCE, AS WELL AS POTENTIAL USES IN ARCHITECTURAL FIELDS. THEY EXHIBIT EXTRAORDINARY STRENGTH AND UNIQUE ELECTRICAL PROPERTIES, AND ARE EFFICIENT THERMAL CONDUCTORS.
CONVENTIONAL SYNTHESIS SOME OF THE IMPORTANT METHODS FOR CNT SYNTHESIS ARE:- ARC DISCHARGE,LASER ABLATION,CHEMICAL VAPOUR DEPOSITION (CVD)CVD IN THIS METHOD A SUBSTRATE IS PREPARED WITH A LAYER OF METAL CATALYST PARTICLES,COMMONLY NICKLE,COBALT,IRON, OR A COMBINATION. THE SUBSTRATE IS HEATED TO APPROXIMATELY 700C. A PROCESS GAS,USUALLY AMMONIA OR HYDROGEN,AND A CARBON-CONTAINING GAS SUCH AS ETHANOL OR METHANE,ARE BLED INTO THE REACTOR. NANOTUBES GROW AT THE SITES OF THE METAL CATALYST; THE CARBON-CONTAINING GAS IS BROKEN APART AT THE SURFACE OF THE CATALYST PARTICLE, AND THE CARBON IS TRANSPORTED TO THE EDGES OF THE PARTICLE, WHERE IT FORMS THE NANOTUBES.
WHAT WE FOUND… ALL THE ABOVE MENTIONED REQUIREMENTS FOR CVD PROCESS ARE AVAILABLE AS WASTE IN THE FURNACES & EXHAUST PIPES OF VARIOUS INDUSTRIES. THE FLUE GAS RELEASED BY THE INDUSTRY HAS CARBON-DIOXIDE, METHANE, NITROGEN, HYDROGEN AND SOME PARTICULATE MATTER. THE CONTENT VARIES ON THE TYPE OF FUEL, BUT THE ABOVE MENTIONED CONSTITUENTS WILL BE MOSTLY PRESENT. THE FURNACE OPERATES AT VERY HIGH TEMPERATURE, PRESSURE AND HAS A NATURALLY GENERATED VACUUM ATMOSPHERE INSIDE IT. THE BURNING OF THE FUEL ENSURES CONTINUOUS SUPPLY OF FLUE GASES. ALL THESE CONDITIONS PRESENT IN THE INDUSTRIAL FURNACES, BOILERS AND EXHAUST PIPES ARE WASTED IN THE FORM OF ENERGY AND MATTED. TAPPING THIS RESOURCE AND BY MODIFYING THE CVD METHOD BY ADEQUATELY MODIFYING THE SUBSTRATES, WE WERE ABLE TO CULTIVATE CNTS SUCCESSFULLY.
HOW WE DID.. THE PREPARATIONS.. SAND COVERED CEMENT SUBSTRATE COATED WITH VARIOUS NANO-SIZED METAL OXIDES. INERT SUBSTRATE: CEMENT SUBSTRATE COATED WITH A LAYER OF SIO 2. CATALYST: Fe 2 O 3,Fe 3 O 4 ( FERROUS OXIDE NANO-PARTICLES), CuO(COPPER OXIDE NANO PARTICLES ),SnO(TIN OXIDE NANO PARTICLES), ZnO(ZINC OXIDE NANO PARTICLES),PbO 2 (LEAD OXIDE NANO PARTICLES) AND NICKEL OXIDE NANO PARTICLES WERE COATED OVER THE INERT SUBSTRATE. SOLUTION FORM OF THE CATALYSTS WERE COATED OVER THE SUBSTRATES AND KEPT IN MUFFLE FURNACE AT 500 0 C TILL THE CATALYST IMPREGNATES IN THE SIO 2 POCKETS. GLASS SUBSTRATES WERE COATED WITH METAL OXIDES BY SPRAY PYROLYSIS. ACETATE FORM OF METALS ACTING AS A SUITABLE CATALYSTS WERE TAKEN AND COATED OVER THE GLASS SUBSTRATES WHICH CAN WITHSTAND HIGH TEMPERATURE(BOROSILICATES). ADEQUATE ARRANGEMENTS TO HOLD THE SUBSTRATES IN THE FURNACE WERE MADE DURING THE SUBSTRATE PREPARATION WORK. TO INCREASE THE SAMPLING EFFECT THE SUBSTRATES WERE PLACED AT THE CENTRE OF THE FURNACE & EXHAUST PIPES BY WELDING A LONG ROD TO THE ROD INBUILT IN OUR SUBSTRATE. ADEQUATE CARE WAS TAKEN TO MINIMIZE HUMAN ERROR IN THE SAMPLING PHENOMENA.
IMPLEMENTATION OF THE IDEA.. TO ENLARGE THE POSSIBILITY OF APPLYING THIS IDEA TO A WIDE RANGE OF INDUSTRIES, WE TESTED OUR TECHNOLOGY IN A SMALL SCALE INDUSTRY,A RICE PROCESSING FACTORY AND A LARGE SCALE INDUSTRY,A THERMAL POWER STATION AT THE NEYVELI LIGNITE CORPORATION(NLC), A CENTRAL GOVERNMENT UNDERTAKING. WE CONDUCTED OUR EXPERIMENT FIRST IN A NEARBY RICE PROCESSING FACTORY, ADJACENT TO SASTRA UNIVERSITY.THE TEMPERATURE OF THE EXHAUST EMISSION AROUND THE EXHAUST PIPE WAS ABOUT 300 0 -400 0 C. AFTER THE EXPERIMENT THE SAMPLES WERE SCRATCHED FROM THE SUBSTRATES AND ANALYSED FOR THE GROWTH OF CNTS AT THE FIELD EMISSION SCANNING ELECTRON MICROSCOPE (FE-SEM) FACILITY AVAILABLE AT THE CENTAB(CENTRE FOR NANOTECHNOLOGY AND ADVANCED BIOMATERIALS), SASTRA UNIVERISTY. SMALL QUANTITY OF THE SAMPLES WERE ALSO ANALYSED BY CHEMICAL METHODS TO CONFORM THE PRESENCE OF CARBON MATTER. THE SEM ANALYSIS REPORT INDICATED THE PRESENCE OF CNTS WITH THE LEAST SIZE OF 27NM(NANOMETRES) FOR THE FE 2 O 3 & FE 3 O 4 SUBSTRATES AND A SIZE RANGE OF 40-50NM FOR CUO SUBSTRATE(FIG. 1 TO 7). HENCE THIS CONFIRMS THE PRESENCE OF CNT GROWTH OVER THE CATALYTIC SUBSTRATE. WE REPEATED THE ENTIRE PROCESS AGAIN, WHICH GAVE US CONSISTENT BATCHES OF CNTS.
Application of the idea on a large scale The catalytic bricks can be coated on the inner walls of the furnace or exhaust pipes. During the working of the batch. Synthesis of CNTs by CVD will occur due the appropriate condition and due to gravity the CNTs will fall to base. Appropriate bases can be constructed to collect the fallen CNTs from the furnace for further treatment. Thus, the collected CNTs can be filtered analysed and stored. A separate small unit( a lab cum plant)can be erected adjacent to the factory to serve all this processing works.
Social Relevance of our technology This technology is of high social and economic relevance as a very useful and costly commodity is generated from a waste that too at a very low cost due to high process efficiency. The flue gas like CO2, CO, CH4 etc. which are causing global warming & other harmful effects are converted to CNTs, which is a very useful material. Application and Uses of CNTs are enumerous.It ranges from mechanical, composites, nano- electronics, biotechnology, material sciences and medical fields etc.
Simplicity and cost effectiveness The entire process is very cost effective. The substrate is very cheap as it is made of sand coated cement bricks. The catalyst is also comparatively cheap and can also be reused in many cases. The manufacturing process is also very easy. The ambience to conduct the experiment is freely available as it is a waste in industry. Overall, this technology is highly cost effective and simple to use, but further optimization of this methodology will make it easier for almost all the industries around the world to utilize this technology in a large scale. But, this technology has to be marketed and the industries should take an initiative in applying it in their industries. This will not only generate an additional revenue to the industry ( one time investment) but also reduce the pollution released by the industries to a considerable extent.
Business plan of our technology Our aim is to start a factory cum Laboratory for substrate manufacturing, CNT analysis, Filtration & batch release. A sales and accounts department to deal with the customers and marketing of the product. A set of efficient workers for the large scale production of substrates and its installation in industries. Procedure for the commercialization of the product: 1.Contact the customers( Industry management division) 2.Analyse the industrial conditions of the furnace and the exhaust pipes i.e Dimensions, temperature, pressure on walls,process and shutdown time. 3.Study the conditions for additional modification required and apprise the customer of the same. 4.Check for the problems that could arise due to implementation of the technology. 5.It will be a permanent setup and the validity of its efficient working will be 3-4 months. After which a coat of the catalyst has to be given by spraying or laminar flow technique across the wall. 6.Collected CNTs can be taken for further processing so as to make it commercial.
Processing of the raw CNTs Carbon nano sheets or wires can be drawn out of the CNTs. The collected CNT can be analyzed using SEM,TEM,EDX,XRD and Malvern zeta sizer(for nano size measurement in a given volume of sample). Then it can be filtered and further characterized based on morphology, size and shape. 1gm of CNTs cost around Rs.50 -80.(current market status).Based on purity and size the cost may still increase. In one day more than 5 kg can be obtained from a plant operating for 14 hrs. in a thermal power industry. Thus after purification lower size CNTs can be directly marketed after packaging in a sealed covered bottles and higher sized CNTs can be used for making reinforced composites,carbon sheets and even as a toner for photocopy machines. Thus this technology is a highly profitable one if implanted in a proper way.