NATURAL AND AGRICULTURAL SCIENCES 3.2. Adsorbent characterization 3.2.1. SEM and EDX analysis The morphology of the adsorbent (SiO 2+ 2@Zn ) was determined using the SEM instrument captured at 20 µm. It showed that the material has an irregular shape and formed some slight aggregates (Figure 2A). The elemental composition (Figure 2B) showed strong signal for silica (Si) at 2Kev and a medium peak representing zinc (Zn) at 0.5 Kev indicating that this material is pure and its synthesis was successful. Figures 2 A and B: Represent SEM images captured at 20 µm and EDX showing the elemental compositions of SiO 2+ 2@Zn . 3.3. Bacterial DNA removal study 3.3.1. Time-concentration profile Effect of time as a function of initial DNA concentration was conducted at intervals while maintaining the adsorbent dose of 20 mg at pH 7.1. It was observed that when contact time was increased from 0 to 80 minutes, percentage adsorption efficiencies increased from 52.60-71.15% at initial DNA concentration of 7.28 µg/mL (Fig.3A) until removal became stable. This result is an indication that increase in time leads to increase in the removal of DNA from aqueous solution. The result is similar to a recently published study (Ezeuko et al., 2022). 3.3.2. Effect of adsorbent dose The adsorbent dose was studied and it is illustrated in Fig 3B. As expected, the percentage removal of bacteria DNA rapidly increased with an increase in sorbent mass from 10 to 30 mg. At 30 mg, the optimum removal efficiencies reached 81.73%. B A Figure 3A and B: Effect of A= time-concentration profile and B = adsorbent dose on the removal of bacteria DNA onto SiO @Zn2+. 2 23 | University of Fort Hare