# Reuse of Spent Coffee Grounds: Alternative Applications, Challenges, and Prospects--A Review
## 7 SCGs as Substrate for Making Containers, Pots, and Cups  
[PERSON] et al. (2017) searched for a suitable binder, intended to be an additive to SCGs and together with them create various structures. The binder tested was Biresin 83, an epoxy resin with a 30% catalyst addition. Also analyzed was the addition of starch (potato and corn) as a natural and biodegradable material, and pine resin, which is readily available. Different weight percentages of SCG additives were tested and then cured at different temperatures and times. Another natural additive analyzed was wax. However, its strength and potential for use in the production of various useful objects was not satisfactory. The additive that showed the best strength when combined with SCGs was polylactic acid (PLA). PLA is a biodegradable thermoplastic material derived from lactic acid from corn or milk. It resembles transparent polystyrene but is rigid and brittle. In addition, it requires modification with plasticizers for practical use. It has been approved by the Food and Drug Administration (FDA) for food packaging. Studies by [PERSON] et al. (2017) using PLA and SCGs show that the higher the proportion of SCGs in the blend, the longer the heating of the materials should be in order for them to combine well. The prepared mixture has good insulation, resistance to contact with hot liquids, and mechanical strength. Although PLA shows good durability and biodegradability, its use in the production of consumer items faces serious limitations. The results do not indicate a limiting time for holding hot liquids in the constructed cups. This can lead to problems with leaking liquids. There is also a design problem, as the manufactured cups cannot be washed in dishwashers due to the high temperature. If this happens, the material can become irreversibly deformed and becomes useless. Future research should focus on developing materials that are more resistant to high temperatures and more flexible, which would increase their potential applications. It is also important to investigate faster and more efficient production processes, as well as alternative biopolymers that could improve  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline  & **Proportion** & \begin{tabular}{c} **Heat of** \\ **Combustion** **(d/kg)** \\ \end{tabular}  & \begin{tabular}{c} **Maximum Heat of** \\ **Combustion** **(d/kg)** \\ \end{tabular}  & \ \begin{tabular}{c} **Minimum Heat of** \\ **Combustion** **(d/kg)** \\ \end{tabular}  & **Process Conditions** & **References** \\ \hline SCGs & - & 22.890 & - & - & - \\ \hline \multirow{3}{*}{SCGs + tea wastes} & 25\% + 75\% & 20.158 & - & - & \\  & 50\% + 50\% & 21.254 & - & - & \\  & 75\% + 25\% & 22.055 & - & - & Fuel sample (dried, ground): 1 g, \\ \hline \multirow{3}{*}{SCGs + straw} & 25\% + 75\% & 20.856 & - & - & \begin{tabular}{c} Fuel sample (dried, ground): 1 g, \\ oxygen atmosphere, pressure of \\ 2 MPa in the calorimetric bomb \\ \end{tabular}  \\  & 75\% + 25\% & 22.138 & - & - & 2 MPa in the calorimetric bomb \\ \hline \multirow{3}{*}{SCGs + pine woods} & 25\% + 75\% & 22.175 & - & - & \\  & 50\% + 50\% & 22.321 & - & - & \\  & 75\% + 25\% & 22.702 & - & - & \\ \hline \multicolumn{3}{l}{Decaffeinated} & 22,500 & 20,600 & \\ \multicolumn{3}{l}{Light roasted} & - & - & 20,800 & 19,000 & \\ \multicolumn{3}{l}{Black roasted} & - & - & 22,600 & 20,800 & Parameters compliant with \\ \multicolumn{3}{l}{Bind:} & \multirow{3}{*}{[45]} & \multirow{3}{*}{[45]} & \multirow{3}{*}{[45]} \\ \multicolumn{3}{l}{decaffeinated +} & & & & & \multicolumn{1}{c}{GOST 147\textasci  
the strength and durability of materials. Another aspect could be research on recycling and cost analysis, which could help scale up the technology further [47]. SCGs can be a potential material for 3D printing. Once used in cups or containers, for example, they are biodegradable and support a closed-loop economy.