Kinetika dan Isoterm Adsorpsi Ion Logam Berat Zn2+ dalam Limbah Cair Kerajinan Batik Kayu Menggunakan Zeolit Alam

The wooden batik craft in Krebet tourism village in Bantul Yogyakarta produces liquid waste with Zn2+ heavy metal content that exceeds the allowed quality standards, thus potentially polluting the environment. One of the simple methods that can be used to reduce Zn2+ concentration is adsorption. This study was aimed to assess the ability of HCl-activated Gunungkidul Yogyakarta natural zeolite as a Zn2+ adsorbent and review its adsorption isotherm. Observations were made with 30, 60, 90, and 120 minutes of contact time variations and adsorbent masses of 0.1, 0.2, 0.3, 0.4, and 0.5 g. The adsorbed Zn metal was tested using an atomic absorption spectrophotometer (AAS). The results showed that HCl-activated natural zeolite effectively reduced the concentration of Zn2+ in the liquid waste from the wood batik dyeing process. A relatively good condition was achieved at a contact time of 90 minutes and an adsorbent mass of 0.3 g, with a Zn2+ concentration in water of 0.117 mg/L, an adsorption efficiency of 96.18%, and an adsorption capacity of 0.4933 mg/g. Analysis results indicated that the adsorption process of Zn2+ from wooden batik craft wastewater fitted to the Weber-Morris kinetic model with a Weber-Morris constant (kWM) of 0.0472 mg/g.min0.5 and the Langmuir isotherm model with Langmuir isotherm constant of 7.2861 L/mg, RL value of 0.0427, and maximum adsorption capacity (qm) of 1.3780 mg/g. The adsorption mechanism was determined by intra-particle diffusion on a monolayer surface.