Polyacrylamide-piperazine-copper oxide nanocomposite hydrogel for biogas purification

Abstract

Polyacrylamide-piperazine-copper oxide nanocomposite hydrogel for biogas purification. The invention teaches a formulation of Polyacrylamide-Piperazine-Copper Oxide Nanocomposite Hydrogel for simultaneous adsorption of CO2 and H2S from raw biogas. Firstly, Aqueous solution of polyacrylamide was prepared by adding 1-5 grams of partially hydrolysed polyacrylamide (PHPA), 1-5 gram of NaCl, 1-5 gram of piperazine in distilled water and mixed uniformly in a mechanical stirrer at 600 rpm. 200-600 ppm of Chromium (III) acetate was added to resultant solution as crosslinker and mixed for 10-30 minutes wherein the gel time is 5-12 hrs for obtaining Polyacrylamide-piperazine-copper oxide nanocomposite hydrogel for biogas purification [FIG. 1].

Specification

Description:4. DESCRIPTION
POLYACRYLAMIDE-PIPERAZINE-COPPER OXIDE NANOCOMPOSITE HYDROGEL FOR BIOGAS PURIFICATION
TECHNICAL FIELD
[0001] The present invention relates to renewable energy and in particular biogas purification systems and methods. The present invention also relates to nanocomposite hydrogels. Further, the invention relates to polyacrylamide piperazine copper oxide-based hydrogels. Further, the present invention specifically relates to polyacrylamide-piperazine-copper oxide nanocomposite hydrogel for biogas purification.
BACKGROUND OF THE INVENTION
[0002] Biogas is a sustainable alternative source of energy, for example can be used as a low cost fuel, but to date there is still a lack of efficiency in its production. Biogas is produced from the anaerobic digestion of organic matter such as animal manure, sewage, and municipal solid waste. The process produces methane and carbon dioxide. After the biogas is processed to required standards of purity, biogas becomes a renewable substitute for natural gas and can be used to fuel natural gas vehicles, helping to replace fossil fuels. Recently, some biogas upgrading technologies are in operation such as physical, chemical, and biological, etc. However, their efficiency and operational conditions, investment and maintenance costs are very high. Therefore, the biogas upgrading market and technologies demand a cost-effective method.
[0003] In one embodiment of prior art, US 9,005,337 B2 teaches a biogas purification system that includes gas processor to remove CO2, VOCs, and H2S from the gas. An optional biological sulphur removal system to treat off gas from the gas processor is discussed in the prior art. A regenerative thermal oxidizer (RTO) system to treat gas from the biological sulphur removal system for thermal destruction of VOCs, H2S, and methane (CH4) slipped from the gas processor. In another embodiment of prior art, US 2011/0023497 A1 teaches a method and apparatus for producing and purifying biogas. It works by first producing biogas from biomass in a fermenter. The biogas is then split into two streams, a methane gas flow and a lean gas flow. The lean gas flow is converted into heat and electricity in a combined heat and power (CHP) plant. It also teaches a bypass line, which allows a variable portion of the crude biogas to be fed directly to the CHP plant, bypassing the separation stage. This allows the operator to adjust the amount of methane and lean gas produced to meet the specific needs of the system. US 9,272,963 B2 teaches a process for the purification by adsorption of a feed flow rich in methane and comprising at least carbon dioxide, employing two exchangers-adsorbers (Ads1, Ads2) of shell-and-tube type.
[0004] The challenges associated with the prior arts are: Water and Polyethylene Glycol Scrubbing: water scrubbing has several drawbacks. It is highly water-intensive, even with regeneration processes. Furthermore, the method has limitations in removing H2S due to the pH-reducing effect of CO2, which also contributes to equipment corrosion caused by H2S. Chemical Absorption: The process is hindered by the need for additional chemical resources and the challenge of managing chemical waste. Pressure Swing Adsorption: PSA technology requires an additional H2S removal step prior to its application, and its tail gas still necessitates treatment. Membrane: Membrane separation is hindered by low methane yield and high membrane costs. While these costs are lower compared to other methods, challenges related to yield, purity, and membrane fouling significantly increase operating expenses. This negatively impacts overall project economics due to the need for frequent membrane replacement. Bio-filter: Biological methods have limitations. They necessitate additional nutrient input for bacterial growth and result in residual oxygen and nitrogen in the treated biogas. H2S removal efficiency is contingent on bacterial activity. Comparative studies indicate that this method is economically viable for capacities up to 40 tons per day. Cryogenic Separation: Cryogenic separation processes are characterized by a substantial equipment requirement, primarily compressors, turbines, and heat exchangers. This equipment-intensive nature leads to elevated capital and operational costs compared to alternative methods. The above discussed technologies suffer from several drawbacks including high operational costs, excessive energy consumption, and suboptimal purification rates. To simplify the process, a low-cost Polyacrylamide-Piperazine-Copper Oxide Nanocomposite Hydrogel is essential as an adsorbent capable of simultaneously capturing both CO2 and H2S. Based on the foregoing a need therefore exists for a polyacrylamide-piperazine-copper oxide nanocomposite hydrogel for biogas purification, as discussed in greater detail herein.
SUMMARY OF THE INVENTION
[0005] The following summary is provided to facilitate an understanding of some of the innovative features unique to the disclosed embodiment and is not intended to be a full description.
[0006] It is, therefore, one aspect of the disclosed embodiments to provide for an improved biogas purification system and method.
[0007] It is another aspect of the disclosed embodiments to provide for an improved nanocomposite hydrogel for biogas purification.
[0008] It is further aspect of the disclosed embodiments to provide for an improved polyacrylamide-piperazine-copper oxide nanocomposite hydrogel for biogas purification.
[0009] Polyacrylamide-piperazine-copper oxide nanocomposite hydrogel for biogas purification. The invention teaches a formulation of Polyacrylamide-Piperazine-Copper Oxide Nanocomposite Hydrogel for simultaneous adsorption of CO2 and H2S from raw biogas. Firstly, Aqueous solution of polyacrylamide was prepared by adding 1-5 grams of partially hydrolysed polyacrylamide (PHPA), 1-5 gram of NaCl, 1-5 gram of piperazine in distilled water and mixed uniformly in a mechanical stirrer at 600 rpm. 200-600 ppm of Chromium (III) acetate was added to resultant solution as crosslinker and mixed for 10-30 minutes wherein the gel time is 5-12 hrs for obtaining Polyacrylamide-piperazine-copper oxide nanocomposite hydrogel for biogas purification.
[0010] Further, the prepared nanocomposite hydrogel is poured into the two adsorption columns connected in series and biogas is allowed to flow through the nanocomposite hydrogel at a flow rate of 1-10 ml/min with the help of low flow pump wherein the raw biogas is allowed to interact with the nanocomposite hydrogel where CO2 and H2S present in the raw biogas is adsorbed by the nanocomposite hydrogel and methane gas is allowed to pass through the top of the adsorption column. The purified methane gas is collected in the collection container and gas analyser is used to measure the composition of purified gas. FIG. 1 describes the flow chart of the proposed double stage biogas purification process.
DETAILED DESCRIPTION
[0011] The values and configurations discussed in these non-limiting examples can be varied and are cited merely to illustrate at least one embodiment and are not intended to limit the scope thereof.
[0012] The embodiments now will be described more fully hereinafter with reference to the accompanying drawings, in which illustrative embodiments of the invention are shown. The embodiments disclosed herein can be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout. As used herein, the term "and/or" includes all combinations of one or more of the associated listed items.
[0013] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
[0014] Invention: Polyacrylamide-piperazine-copper oxide nanocomposite hydrogel for biogas purification. The invention teaches a formulation of Polyacrylamide-Piperazine-Copper Oxide Nanocomposite Hydrogel for simultaneous adsorption of CO2 and H2S from raw biogas. Firstly, Aqueous solution of polyacrylamide was prepared by adding 1-5 grams of partially hydrolysed polyacrylamide (PHPA), 1-5 gram of NaCl, 1-5 gram of piperazine in distilled water and mixed uniformly in a mechanical stirrer at 600 rpm. 200-600 ppm of Chromium (III) acetate was added to resultant solution as crosslinker and mixed for 10-30 minutes wherein the gel time is 5-12 hrs for obtaining Polyacrylamide-piperazine-copper oxide nanocomposite hydrogel for biogas purification.
[0015] Further, the prepared nanocomposite hydrogel is poured into the two adsorption columns connected in series and biogas is allowed to flow through the nanocomposite hydrogel at a flow rate of 1-10 ml/min with the help of low flow pump wherein the raw biogas is allowed to interact with the nanocomposite hydrogel where CO2 and H2S present in the raw biogas is adsorbed by the nanocomposite hydrogel and methane gas is allowed to pass through the top of the adsorption column. The purified methane gas is collected in the collection container and gas analyser is used to measure the composition of purified gas. FIG. 1 describes the flow chart of the proposed double stage biogas purification process.
[0016] Working of the invention: The invention teaches a Polyacrylamide-Piperazine-Copper Oxide Nanocomposite Hydrogel material composed of polyacrylamide polymer, sodium chloride, Piperazine, Copper oxide nanoparticles and chromium (III) acetate as crosslinker. The material exhibited the presence of polyacrylamide, Piperazine, Copper oxide nanoparticles and NaCl in varying percentage of 1-5%. The materials are synthesized from an aqueous solution of plyacrylamide, Piperazine, Copper oxide nanoparticles and NaCl with varying concentration of 1-5%. The crosslinker concentration may vary from 200 ppm to 600 ppm. The material could be crosslinked chemically for further increasing the adsorption efficiency. The material is light black in color after crosslinking. The formulation showed high adsorption efficiency of CO2 and H2S from biogas. FIG. 2 illustrates the experimental set up for double stage biogas purification using Polyacrylamide-Piperazine-Copper Oxide Nanocomposite Hydrogel adsorption columns. The composition of purified biogas is claimed to contain 96-98 % of methane and 2-4 % of CO2. The purified biogas can be used as Compressed Bio-Methane in the automobile sector. Considering its physicochemical and biodegradation properties, this nanocomposite hydrogel may qualify as a suitable adsorbent for biogas purification. Table 1 describes the numerical values of the compositions present
in the biogas before and after purification.
Compositions Raw Biogas Purified Biogas
CH4 54.64% 96-98%
CO2 41.43% 2-4%
H2S 204 ppm 0 ppm



[0017] It will be appreciated that variations of the above-disclosed and other features and functions, or alternatives thereof, may be desirably combined into many other different systems or applications. Also that various presently unforeseen or unanticipated alternatives, modifications, variations or improvements therein may be subsequently made by those skilled in the art which are also intended to be encompassed by the following claims.
, Claims:5. CLAIMS
I/We Claim
1. A method for obtaining polyacrylamide-piperazine-copper oxide nanocomposite hydrogel for biogas purification, comprising steps of:
aqueous solution of polyacrylamide was prepared by adding 1-5 grams of partially hydrolysed polyacrylamide (PHPA), 1-5 gram of NaCl, 1-5 gram of piperazine in distilled water and mixed uniformly in a mechanical stirrer at 600 rpm;
200-600 ppm of Chromium (III) acetate was added to resultant solution as crosslinker and mixed for 10-30 minutes wherein the gel time is 5-12 hrs for obtaining Polyacrylamide-piperazine-copper oxide nanocomposite hydrogel for biogas purification wherein the formulation of polyacrylamide-Piperazine-Copper Oxide Nanocomposite Hydrogel is used for simultaneous adsorption of CO2 and H2S from raw biogas.
2. The method as claimed in claim 1 wherein the polyacrylamide-Piperazine-Copper Oxide Nanocomposite Hydrogel nanocomposite is poured into the two adsorption columns connected in series and biogas is allowed to flow through the nanocomposite hydrogel at a flow rate of 1-10 ml/min with the help of low flow pump wherein the raw biogas is allowed to interact with the nanocomposite hydrogel where CO2 and H2S present in the raw biogas is adsorbed by the nanocomposite hydrogel and methane gas is allowed to pass through the top of the adsorption column.
3. The method as claimed in claim 1 wherein the purified methane gas is collected in the collection container and gas analyser is used to measure the composition of purified gas.
4. The method as claimed in claim 1 the Polyacrylamide-Piperazine-Copper Oxide Nanocomposite Hydrogel material composed of polyacrylamide polymer, sodium chloride, Piperazine, Copper oxide nanoparticles and chromium (III) acetate as crosslinker wherein the polyacrylamide, Piperazine, Copper oxide nanoparticles and NaCl are synthesized from an aqueous solution of plyacrylamide, Piperazine, Copper oxide nanoparticles and NaCl with varying concentration of 1-5%.
5. The method as claimed in claim 1 wherein the crosslinker concentration may vary from 200 ppm to 600 ppm wherein the material is light black in color after crosslinking showing high adsorption efficiency of CO2 and H2S from biogas.

6. SIGNATURE WITH DATE

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