Development process of composite polymer tiles with an antimicrobial agent using plastic wastes as raw materials

Plastic is a delinquent substance that affects all ecosystems. Unfortunately, plastic is being utilized more frequently than it was previously used. The bad dispatch is that they are thrown away in the wild once they have been used. Their buildup does not degrade, and it is harmful to the environment. An appropriate procedure for recovering plastic wastes and converting them into standardized material to produce composite tiles with their application can be a viable solution to this dangerous situation. The paper aims to find an effective means of disposing of plastic waste by designing and developing plastic tiles with the insertion of antimicrobial properties. At first, plastic waste was collected, cleaned, and shredded accordingly. Then the waste plastic is melted in a pyrolysis plant, mixed with sand, and poured into the prefabricated mold. As a walkway tile, the mold size was chosen as 12-inch length, 10-inch width, and 0.8-inch height. It has been found that 70 % sand and 30 % plastic exhibit better mechanical properties. For the insertion of antimicrobial properties into the tiles, ginger powder is added to the mixture of the composite tiles. An antibacterial study was performed against gram-positive S. aureus bacteria to evaluate their antimicrobial property. The analysis shows that the composite tiles could kill 40.58% gram-positive S. aureus in six hours.


Introduction
The utilization of plastic polymer tiles can be versatile.It is always appreciated if the polymer tiles with the required properties can be used in multipurpose sectors.If the product is viable from technical, economic, and environmental points of view, the acceptability of it for multipurpose use will be more justified.Antimicrobial properties in polymer tiles will make them more beneficial for different purposes in day-to-day life.Since antimicrobial agents will resist the normal growth of microbes on any exposed surface, an endeavour has been made in this research work to insert antimicrobial agents inside plastic waste-turned-polymer tiles [1,2].Antimicrobial properties can be inserted into the product by applying various techniques.The methods for producing polymer tiles that can decrease the spread of microbial organisms are still mostly unexplored.To date, there is no available research about the modification or treatment of the surface 1305 (2024) 012020 IOP Publishing doi:10.1088/1757-899X/1305/1/012020 2 of composite polymer tiles to reduce the risk of pathogen transmission.Nonetheless, the technical literature demonstrates several methods that can be functional on the plastic waste-turned-polymer tiles to incorporate antimicrobial properties [3,4].The use of such samples as footpath tiles in Bangladesh is an alternative to the traditional ceramic tiles available on the market.On the other hand, the problem associated with an increased amount of plastic waste during COVID-19 could be a solution to getting rid of plastic waste [5].

Portrayal of Antimicrobial Agents
Antimicrobial agents can be categorized into two types: chemical agents which directly kill or reduce the growth of microbes, and physical means to inhibit the growth of microbes.Chemical agents which act as antimicrobials may be further categorized into the following: a. Antibacterial/antibiotics. b.Antiviral.c. Antiparasitic.d.Antifungals.e. non-pharmaceutical such as organic acids, copper, halogens, ozone, phenol, and phenolic compounds, etc. f.Organic plants such as oregano, basil, garlic, ginger, peppermint, etc.Some of the physical parameters which can be utilized to augment the antimicrobials are as follows: a. Heat b.Radiation c. Desiccation d.Osmotic pressure Antimicrobial agents can also be classified based on their target specifications.Thus, it can be either a narrow or broad spectrum that has been recently accepted in academic research and industrial fields [6].The narrow-spectrum antimicrobial works against only Gram-positive or Gram-negative bacteria.
On the other hand, the broad-spectrum antibacterial can be used against both Gram-positive and Gram-negative bacteria.Researchers have discovered that narrow-spectrum antibacterial is more effective than broad-spectrum antibacterial.Usually, narrow-spectrum antibiotics do not necessarily kill all microorganisms present in the body like broad-spectrum antibiotics do.Thus, narrow-spectrum antibacterial does not cause superinfection.
Once any microbe infects a surface, it becomes vulnerable to spreading the microorganisms to more than seven or eight clean surfaces by people contacting those surfaces.As improper cleaning of exposed surfaces will increase the chances of surviving microorganisms, any surface with antimicrobial properties will help minimize the transmission through any exposed surfaces.Again, microorganisms that can survive on exposed surfaces may result in respiratory disease through contact [7].
The scientific forum's design and development of polymeric materials with antimicrobial properties have obtained increased consideration as a safe and active means to guard against microbes.Efforts have been made in this research work to develop plastic waste-turned-polymer tiles with antimicrobial properties, which will contribute to the killing, reducing the growth of microbes and complementing the disinfectant measures of any exposed surface.

Antimicrobial Properties Insertion Techniques
The antimicrobial properties can be inserted into a product or material by applying any of the following processes: a. Employment of antimicrobial compounds such as biocidal doping through mixing chemical agents.b.Polymers with intrinsically pathogen-resistant properties, such as the insertion of antimicrobial polymeric material.c.Metallic surface coatings such as CuO, AlO, Ag2O, etc. d.Surface modification by the process of nanotexturing.e. Organic Plants mix in the form of powder or liquid.
Microorganisms on any exposed surface depend on four main properties [8].These are (i) physical properties such as porosity; (ii) relative humidity, temperature, exposure to light, and type of surface (iii) biological characteristics of the microbes, the structure of the virus or presence of other microorganisms (iv) pH value of the material/surface, attendance of reactive ions, adsorption state, presence of bioactive component, presence of organic compound or substances with antimicrobial properties.Few heavy metals possess antimicrobial properties and have the potential to interact with microorganisms.For example, silver (Ag), gold (Au), bismuth (Bi), cobalt (Co), copper (Cu), iron (Fe), mercury (Hg), manganese (Mn), nickel (Ni), lead (Pb), platinum (Pt), antimony (Sb), tin (Sn), titanium (Ti), and zinc (Zn) are having anti-infective properties against microbes.Polymers with antimicrobial properties vary from natural biopolymers with intrinsic antimicrobial properties to synthetic thermoplastic elastomers.At the same time, biopolymers are naturally derived materials.The use of biopolymers has grown interesting for their biocompatibility and intrinsic antimicrobial properties [9].Composite materials allow a comprehensive and significant way for incorporating useful materials with antimicrobial properties.Combining several materials or including antimicrobial moieties, such as metals, into quickly moldable materials (polymers) allows for the required antimicrobial properties of materials [10].However, mixing organic plants in powder or liquid form with polymer tiles is a feasible method of antimicrobial insertion technique.

Organic Plants with Antimicrobial Activity
From ancient times, organic plants and herbs have been used as a natural medicine for numerous diseases, including contaminations caused by microorganisms.Since there is a presence of potential antimicrobial compounds in many organic plants, it assists in acting against microbes.The following organic plants have significant antimicrobial properties: Oregano: Oregano is a plant of the mint family, and it is known for its notable medicinal qualities.This plant includes carvacrol which offers antimicrobial properties.Oregano oil and carvacrol also exhibit antiviral activity against herpes simplex virus type-1 (HSV-1); rotavirus is commonly responsible for diarrhea in infants and children.Oregano also treats breathing contaminations instigated by a respiratory syncytial virus (RSV).Basil: Varieties of basil leaves (Also known as Tulsi) may fight against certain viral infections.Basils contain apigenin and ursolic acid, exhibiting potential antimicrobial properties against herpes viruses, hepatitis B, and enterovirus.It is also seen that basil leaves increase immunity inside the human body, thus helping to fight against viral infections.Extracts of basil leave significantly increase helper T cells and natural killer cells which protect and defend our body from various infections caused by microorganisms.Garlic: Garlic is a widely used natural antimicrobial.Garlic is also used to treat viral infections for ages.Garlic extract has been seen as very effective in curing the infection caused by Human papillomavirus (HPV).In addition, many researchers have mentioned that garlic may have antiviral activity against influenza A and B, HIV, HSV-1, viral pneumonia, and rhinovirus, which has been identified as the main reason for the common cold.Peppermint: Peppermint has good antiviral qualities, and extracts of peppermint are commonly used to treat viral infections.Its leaves and essential oils contain a few active components that have good antimicrobial properties, such as menthol and Rosmarinus acid.Research shows that extracts from peppermint leaves can perform antiviral activity against the respiratory syncytial virus (RSV).It can also meaningfully decrease the levels of provocative compounds.Ginger: Ginger has several active antimicrobial constituents, such as phenolic and terpene compounds.Considering the availability of Ginger from the perspective of Bangladesh, an endeavor had been made in this research work to utilize the antimicrobial properties of Ginger for its incorporation in the plastic waste-turned-polymer tiles to obtain antimicrobial properties.

Sample Tiles preparation
One prototype pyro furnace has been prepared to melt the heterogeneous plastic.Before pouring into the furnace, fine sand (construction grade) was added to have the desired molding and mechanical blondness of the product.For the preparation of the plastic waste turned polymer tiles with antimicrobial agents, 70% sand and 30% heterogeneous plastic waste composition has been considered since they provide the best physical properties for the polymer tiles.

Test of Polymer Tiles Modified with Antimicrobial Agents
To assess the antimicrobial effectiveness of tiles, the antibacterial study was performed against grampositive S. aureus by colony counting method for three samples from the accepted composition of 70% sand and 30% heterogeneous plastic.For each sample, firstly a single colony of bacteria was cultured in nutrient broth overnight at 37℃.The samples untreated and treated with an antimicrobial agent of approximately 2.4 gm were placed in 15 mL of diluted broth separately and kept in the incubator at 37℃ with adequately capped.At specified time pauses, the bacterial solution was diluted in sterilized saline.About 100 µL from the bacterial solution with samples was plated in nutrient agar and placed in the incubator overnight at 37℃.After 2-6 hours, the surviving colonies of each time interval were counted.The percent of bacteria killed at the prescribed Here, N0 = the number of living bacteria in the control/antimicrobial loaded sample at 0 hr, and Nt = the number of bacteria at a specific time t hr in the control/ antibacterial property loaded sample.

Mechanical Property
The test results of compressive strength, flexural strength, impact load, hardness, friction coefficient, and moisture content have been tabulated in Table 1 and the results confirm the suitability of the plastic tiles on the local footpath.TGA analysis (Fig. 3) shows the thermal stability of the plastic tiles on sunny days.Fig 4 shows the FTIR analysis of the pavement tiles made with 70% Sand and 30% Heterogenous plastic waste.Finally, SEM images (Fig. 5) of the plastic tiles show the uniform boding/distribution of sand and heterogenous plastic.

Antiviral Property
Control (untreated) and samples with antibacterial properties (treated) were evaluated against grampositive S. aureus bacteria [11].The increase of bacteria in the control sample is shown in the first chart at different time intervals, whereas the reduction of bacteria in the sample with antibacterial properties is shown in the second chart.In the first two hours, the treated sample killed 1.59% bacteria, whereas in six hours it killed 40.58% bacteria.Bacteria in the sample with the number of antimicrobial agents (untreated) has been increased by 67.37% in the first two hours and 118.67% in the first six hours.Fig. 5 shows the images of the agar plate for surviving S. aureus bacteria of the control sample (untreated).Fig. 7 shows the images of the agar plate of the sample with an antimicrobial agent and surviving S. aureus bacteria at different time intervals.Table 2 shows the bacteria counting at different time intervals.Here it is noticeable that the number of bacteria increases around the control sample (untreated), whereas the colony counting method has significantly observed the bacteria reduction in the sample with modified properties (treated).For controlled samples it has been found -  The various figures mentioned below show the level of bacteria according to their number and percentage, respectively.Fig. 8 shows the number of surviving bacteria in the control sample in hours without antimicrobial properties.Here it is observed that many bacteria significantly increase in touch with the control sample without modification.The reverse trend is observed in Fig. 9, showing the number of surviving bacteria in the sample with antimicrobial properties in Hours.Here it is observed that the number of bacteria significantly diminished while the bacterial colonies remained in touch with the polymer tiles with antimicrobial properties, and the diminishing of the bacterial colonies goes up with the increase of time interval.With the increased time interval, the number of bacteria decreases in touch with polymer tiles with modified properties.Fig. 10 shows the % of S. aureus Bacteria increase in the control sample.This figure shows the % of surviving bacteria in the control sample within hours without antimicrobial properties.Here it is pragmatic that the % of bacteria meaningfully upsurge in touch with the control sample without modification.Fig. 11 shows the % of S. aureus Bacteria Killed in the sample with the antimicrobial property.This figure shows the % of bacteria killed in touch with the sample in hours in the presence of the sample with the antimicrobial property.Here it is observed that the % of bacteria significantly decreased in touch with the sample modified with antimicrobial properties.For test samples number 2 and 3, both untreated/control samples and treated samples/sample with the antimicrobial agent was tested against germ-positive S. aureus bacteria.The test result is shown in Table 3 and Table 4.
For test sample 2, in the first two hours, the treated sample killed 6.33% bacteria, whereas in six hours it killed 42.20% bacteria.Bacteria in the sample with the antimicrobial agent (untreated) increased by 79.17% in the first two hours and 155.39% in the first six hours.Finally, Fig. 14 shows the % of bacteria killed in samples with the antimicrobial agent in hours.It has been observed that the antimicrobial agents (Ginger) could kill a maximum of 6.63% of bacteria in the first 2 hours and 47.32% of bacteria in the first 6 hours.

Conclusion
Materials with antimicrobial properties are important for use in various walks of life.Any exposed surface is suspected to assist the growth of microbes.Considering this factor several approaches have been discussed in this chapter for incorporating antimicrobial properties in the material.Initially, the portrayal of microorganisms and various measures to kill or control their growth and replication was discussed from a scientific point of view.The categories of antimicrobial agents such as chemical and physical parameters, were reviewed for further adaptation of the best method of antimicrobial property insertion.Then the effects on microorganisms by polymeric antimicrobial agents, biopolymers, and antimicrobial components of the organic plant were considered thoroughly.
Taking the best composition of heterogeneous plastic waste and sand for polymer tiles, powdered ginger, and ginger leaves were mixed accordingly to prepare the sample for the antimicrobial behaviours of the product.To evaluate the antibacterial efficacy of polymer tiles, an antibacterial study was performed against gram-positive S. aureus by colony counting.The study found that in the first two hours, the sample with antimicrobial could kill a maximum of 6.63% gram-positive S. aureus whereas, in six hours, it could kill a maximum of 47.32% gram-positive S. aureus bacteria.

Figure 1 .
Figure 1.Flow Chart of the manufacturing process of Plastic TilesOn the other hand, matured leaves of the ginger plants and raw ginger have been plugged and cleaned properly to avoid foreign particles like particulate material, dust, etc.Then the leaves and fresh ginger have been dried up naturally by sunlight under ambient conditions.The powder of ginger was added and started for uniform mixing with the said composition of the sample product when the temperature of the furnace became 100 to 130°C.Fig.1illustrates the flow diagram of the manufacturing process of the plastic tiles, and the die and fabricated polymer tiles are shown in Fig.2.

Figure 2 .
Figure 2. Picture of die and polymer tiles

Figure 6 .
Figure 6.Images of agar plate for surviving S. aureus bacteria of the control sample (untreated)

Figure 7 .
Figure 7. Images of agar plate for surviving S. aureus bacteria of Sample with antibacterial properties (treated)

Figure 12 .
Figure 12.Quantity of living bacteria in control samples (untreated) in hours

Number of surviving bacteria with blank sample no 1 Number of surviving bacteria with blank sample no 2
Number of surviving bacteria with blank sample no 3

Figure 13 .
Figure 13.Quantity of living bacteria in samples with antimicrobial agents (untreated) in hours Figure 14.% of bacteria killed in samples with the antimicrobial agent in hours

Table 1 .
Mechanical properties of the plastic tiles Figure 3. TGA Test Results of Specimen (70% Sand and 30% Heterogenous plastic waste)

Table 2 .
Bacteria counting in different time intervals for Sample 1(for both treated and untreated samples with an antimicrobial agent)

Table 3 .
Bacteria counting in different time intervals for Sample 2 (for both treated and untreated samples with the antimicrobial agent)

Table 4 .
Bacteria counting in different time intervals for Sample 3 (for both treated and untreated samples with an antimicrobial agent) For test sample 3, in the first two hours, the treated sample killed 2.23% bacteria, whereas in six hours it killed 47.32% bacteria.Bacteria in the sample with an antimicrobial agent (untreated) increased by 66.7% in the first two hours and 122.03% in the first six hours.