Efektivitas Komposit Zeolit Alam dan Karbon Aktif Tempurung Kelapa terhadap Penyisihan Fosfat

Abstract

Phosphate is one of the major pollutants in shrimp pond wastewater originating from uneaten feed and shrimp metabolism. Excessive phosphate concentrations may degrade aquatic ecosystems; therefore, effective treatment is required before wastewater discharge. This study aimed to evaluate the effectiveness of a natural zeolite and KOH-activated coconut shell activated carbon composite in removing phosphate from shrimp pond wastewater and to investigate the effects of adsorbent mass and contact time on phosphate removal efficiency. The composite adsorbent was prepared using a 1:1 mass ratio of natural zeolite and KOH-activated coconut shell activated carbon. Adsorption experiments were conducted using the batch method with adsorbent mass variations of 0.5, 1.0, 1.5, and 2.0 g and contact time variations of 30, 60, 90, and 120 min at a stirring speed of 200 rpm. Characterization of the adsorbent showed that the activated carbon met the Indonesian National Standard (SNI 06-3730-1995). The results of the FTIR analysis test confirmed the presence of hydroxyl functional groups (–OH) which act as active adsorption sites. The highest phosphate removal efficiency of 65.61% was achieved using 1 g of adsorbent at 120 min, resulting in a final phosphate concentration of 3.07 mg/L. Kinetic analysis indicated that phosphate adsorption followed the pseudo-first-order model at adsorbent masses of 0.5 and 1.5 g, whereas the pseudo-second-order model better represented adsorption at 1 and 2 g. Two-way ANOVA demonstrated that both adsorbent mass and contact time significantly affected phosphate removal efficiency (p < 0.05). These findings indicate that the natural zeolite and KOH-activated coconut shell activated carbon composite has good potential as an environmentally friendly adsorbent for phosphate removal from shrimp pond wastewater.