Electronic Theses and Dissertation

Industri tekstil menghasilkan limbah cair yang mengandung zat warna sintetis seperti rhodamine b yang bersifat toksik, karsinogenik, dan sulit terdegradasi secara alami. oleh karena itu, diperlukan metode pengolahan limbah yang efektif, ekonomis, dan ramah lingkungan. penelitian ini bertujuan untuk memanfaatkan limbah kulit jagung (zea mays l.) sebagai bahan baku biosorben melalui proses pirolisis dan aktivasi kimia menggunakan hcl, serta mengevaluasi kinerja adsorpsinya terhadap rhodamine b. proses adsorpsi dilakukan secara batch dengan variasi konsentrasi rhodamine b 2-10 ppm, waktu kontak 15-90 menit, dan suhu 30–70°c. konsentrasi akhir dianalisis menggunakan spektrofotometer uv–vis untuk menentukan kapasitas adsorpsi dan efisiensi penyisihan. karakterisasi adsorben meliputi uji kadar air, kadar abu, daya serap iodin, ftir, sem, xrd, serta analisis luas permukaan bet. hasil penelitian menunjukkan bahwa adsorpsi berlangsung cepat pada tahap awal dan mencapai kesetimbangan sekitar menit ke-75 dengan efisiensi penyisihan mendekati 100% pada kondisi optimum. peningkatan suhu dan konsentrasi awal meningkatkan kapasitas adsorpsi, yang mengindikasikan proses bersifat endotermik. analisis isoterm menunjukkan bahwa data kesetimbangan adsorpsi rhodamine b lebih tepat dijelaskan oleh model langmuir (r2 = 0,9991) dibandingkan model freundlich (r2 = 0,8856). hasil ini mengindikasikan bahwa adsorpsi terutama berlangsung sebagai pembentukan lapisan tunggal (monolayer) pada permukaan adsorben yang secara efektif relatif homogen. kinetika adsorpsi paling sesuai mengikuti model pseudo second order (pso) dengan nilai r2 tertinggi sebesar 0,9952. kesesuaian pso menunjukkan bahwa laju adsorpsi sangat dipengaruhi oleh keterisian atau aksesibilitas situs aktif dan interaksi permukaan selama proses berlangsung. namun, jika dikaitkan dengan hasil termodinamika (Δg° negatif dan Δh° positif) yang mengarah pada fisisorpsi dominan, maka mekanisme adsorpsi dalam penelitian ini lebih tepat dipahami sebagai fisisorpsi yang dominan dengan kemungkinan adanya interaksi spesifik pada sebagian situs aktif (bukan murni ikatan kimia kuat pada seluruh permukaan).

The textile industry generates wastewater containing synthetic dyes such as Rhodamine B, which are toxic, carcinogenic, and resistant to natural degradation. Therefore, an effective, economical, and environmentally friendly treatment method is required. This study aims to utilize corn husk waste (Zea mays L.) as a biosorbent precursor through pyrolysis and chemical activation using HCl, and to evaluate its adsorption performance for Rhodamine B removal. Batch adsorption experiments were conducted by varying the initial Rhodamine B concentration (2–10 ppm), contact time (15–90 min), and temperature (30–70°C). The final dye concentration was measured using a UV–Vis spectrophotometer to determine adsorption capacity and removal efficiency. Adsorbent characterization included moisture content, ash content, iodine number, FTIR, SEM, XRD, and BET surface area analysis. The results showed that adsorption proceeded rapidly at the initial stage and reached equilibrium at approximately 75 minutes, achieving nearly 100% removal efficiency under optimum conditions. Increasing temperature and initial concentration increased the adsorption capacity, indicating an endothermic process. Isotherm analysis demonstrated that the equilibrium data were better described by the Langmuir model (R2 = 0.9991) than by the Freundlich model (R2 = 0.8856), suggesting that adsorption mainly occurred as monolayer coverage on an effectively homogeneous adsorbent surface. The adsorption kinetics were best fitted by the pseudo second order (PSO) model with the highest R2 of 0.9952, implying that the adsorption rate was strongly influenced by the availability/accessibility of active sites and surface interactions during the process. However, when interpreted together with the thermodynamic results (negative ΔG° and positive ΔH°), which point to a predominantly physisorption-controlled mechanism, the adsorption in this study is more appropriately described as physisorption-dominated with the possible contribution of specific interactions at certain active sites rather than purely strong chemical bonding across the entire surface.