**2. Materials and methods**

### **2.1 Preparation of waste tyre carbon materials**

Two forms of carbon residues were considered during this research study on the characterization and development of a sustainable adsorption material for mercury vapor recovery. One form of the carbon residue was sourced from waste tyre pyrolysis by-product, the carbon black residue by RECO, a waste to energy Solution Company based in Pretoria, Gauteng province. The other carbon residue sample was a commercially available activated carbon collected from RECLITE, a fluorescent lamp waste recycling company based in Germiston, Johannesburg, Gauteng Province in South Africa. The company, RECLITE, has imported the fluorescent lamp recycling plant, including the activated carbon filter cartridges from Sweden. The commercial grade Activated Carbon was produced and supplied by MRT Systems, Swedish based company specializing in technology and equipment for the safe disposal/recycling of mercury containing waste products. All chemicals and reagents were obtained from Sigma-Aldrich Merck and used as received unless stated otherwise. Sulfuric acid (95–99% H2SO4), hydrogen hydroxide (H2O2), and 32% hydrochloric acid (HCl). The experimental materials include the following: Electric Oven (0–300°C), 100 mL volumetric flasks, de-ionized water, desiccator, vacuum filter, drying oven (Temperature 90–120°C for drying Carbon black C\char), and the Carbon black (CB) was collected RECOR. The carbon black was taken into the oven (Scientific Oven Series 2000 Labotec SA) at 120°C to dry. After drying, it was crushed and sieved into smaller pieces of about 0.85–0.1 mm internal diameter (**Figure 1A** and **B**). The as-prepared sieved carbon black material was stored in an Oven at 100°C prior to activation.

### **2.2 Activation of carbon black**

Activated carbon (AC) was prepared from waste tyre pyrolytic carbon black using one-step chemical activation method [5]. The two different chemical activating agents, Sulfuric acid (H2SO4) and hydrogen peroxide (H2O2) were used in this study, in a 1:4 ratio (carbon black: agent).

**Figure 1.** *(A) Grinding of commercial grade AC; (B) prepared raw and commercial AC samples ready for characterization.*
