Electronic Theses and Dissertation

Limbah biomassa mahkota nanas dan kulit alpukat berpotensi dikembangkan sebagai sumber material adsorben berbasis biochar untuk mengatasi pencemaran logam berat pb(ii), cd(ii), dan cu(ii). penelitian ini bertujuan untuk mengembangkan dan mengoptimalkan hidrogel komposit berbasis biochar dari kedua biomassa tersebut sebagai adsorben untuk adsorpsi simultan logam berat. biochar disintesis melalui pirolisis pada suhu 500 °c, kemudian diaktivasi menggunakan naoh 35% selama 24 jam. biochar teraktivasi selanjutnya dimodifikasi dengan poliakrilamida untuk membentuk hidrogel komposit dengan variasi berat biochar 1, 3, dan 5 g. hasil karakterisasi ftir menunjukkan adanya gugus fungsional aktif –oh, –nh, –c=o, dan –c–o yang berperan dalam pengikatan ion logam. analisis morfologi menunjukkan bahwa penambahan biochar meningkatkan porositas struktur hidrogel. hbm memiliki luas permukaan spesifik 767,707–846,923 m²/g dengan volume pori total 0,787 cm³/g, sedangkan hba memiliki luas permukaan spesifik 773,854–802,409 m²/g dengan volume pori total 0,587 cm³/g. penambahan biochar juga meningkatkan kemampuan swelling, dengan nilai tertinggi sebesar 357,14% pada hbm1 dan 374,592% pada hba3. analisis kinetika menunjukkan bahwa proses adsorpsi mengikuti model pseudo-second-order dengan nilai r² sebesar 0,92–0,98 untuk hbm dan 0,98–0,99 untuk hba, yang mengindikasikan dominasi mekanisme kemisorpsi. optimasi adsorpsi dilakukan menggunakan metode rsm–box-behnken berbasis desirability dengan variabel berat adsorben, waktu adsorpsi, dan kecepatan pengadukan. kondisi optimum hbm untuk respon kapasitas adsorpsi diperoleh pada berat adsorben 1 g, waktu adsorpsi 2,02 jam, dan kecepatan pengadukan 100 rpm, dengan kapasitas adsorpsi pb(ii), cd(ii), dan cu(ii) masing-masing sebesar 4,758 mg/g; 4,157 mg/g; dan 4,861 mg/g. kondisi optimum hbm untuk respon efisiensi adsorpsi diperoleh pada berat adsorben 2,70 g, waktu adsorpsi 1,47 jam, dan kecepatan pengadukan 100,06 rpm, dengan efisiensi adsorpsi pb(ii), cd(ii), dan cu(ii) masing-masing sebesar 45,597%; 42,277%; dan 44,917%. pada hba, kondisi optimum untuk respon kapasitas adsorpsi diperoleh pada berat adsorben 1 g, waktu adsorpsi 1 jam, dan kecepatan pengadukan 118,51 rpm, dengan kapasitas adsorpsi pb(ii), cd(ii), dan cu(ii) masing-masing sebesar 1,913 mg/g; 1,342 mg/g; dan 1,465 mg/g. kondisi optimum hba untuk respon efisiensi adsorpsi diperoleh pada berat adsorben 8,45 g, waktu adsorpsi 5 jam, dan kecepatan pengadukan 150 rpm, dengan efisiensi adsorpsi pb(ii), cd(ii), dan cu(ii) masing-masing sebesar 32,612%; 28,390%; dan 27,831%. secara keseluruhan, hbm menunjukkan kinerja adsorpsi simultan yang lebih tinggi dibandingkan hba, baik dari aspek kapasitas maupun efisiensi adsorpsi, sedangkan hba menunjukkan kecenderungan adsorpsi yang lebih dominan terhadap pb(ii). hasil ini menunjukkan bahwa hidrogel komposit berbasis biochar mahkota nanas dan kulit alpukat berpotensi digunakan sebagai adsorben alternatif untuk pengolahan air tercemar logam berat.

Pineapple crown and avocado peel biomass wastes have considerable potential for development as biochar-based adsorbent materials for the removal of heavy metals, particularly Pb(II), Cd(II), and Cu(II), from contaminated water. This study aimed to develop and optimize biochar-based hydrogel composites derived from pineapple crown and avocado peel for the simultaneous adsorption of heavy metal ions. Biochar was synthesized via pyrolysis at 500 °C and subsequently activated with 35% NaOH for 24 h. The activated biochar was then incorporated into a polyacrylamide matrix to produce hydrogel composites with biochar loadings of 1, 3, and 5 g. FTIR analysis confirmed the presence of active functional groups, including –OH, –NH, –C=O, and –C–O, which contributed to metal ion binding. Morphological analysis revealed that biochar incorporation enhanced the porosity of the hydrogel structure. The HBM exhibited a specific surface area of 767.707–846.923 m²/g and a total pore volume of 0.787 cm³/g, whereas the HBA showed a specific surface area of 773.854–802.409 m²/g and a total pore volume of 0.587 cm³/g. Biochar incorporation also improved the swelling capacity of the composites, with the highest swelling values of 357.14% for HBM1 and 374.592% for HBA3. Kinetic analysis demonstrated that the adsorption process followed the pseudo-second-order model, with R² values of 0.92–0.98 for HBM and 0.98–0.99 for HBA, indicating that chemisorption was the dominant adsorption mechanism. Adsorption optimization was conducted using desirability-based response surface methodology with a Box–Behnken design, in which adsorbent dosage, adsorption time, and stirring speed were selected as independent variables, while adsorption capacity and removal efficiency were used as response variables. For HBM, the optimum condition for adsorption capacity was obtained at an adsorbent dosage of 1 g, adsorption time of 2.02 h, and stirring speed of 100 rpm, resulting in Pb(II), Cd(II), and Cu(II) adsorption capacities of 4.758, 4.157, and 4.861 mg/g, respectively. The optimum condition for HBM removal efficiency was achieved at an adsorbent dosage of 2.70 g, adsorption time of 1.47 h, and stirring speed of 100.06 rpm, yielding Pb(II), Cd(II), and Cu(II) removal efficiencies of 45.59, 42.277%, and 44.917%, respectively. For HBA, the optimum condition for adsorption capacity was obtained at an adsorbent dosage of 1 g, adsorption time of 1 h, and stirring speed of 118.51 rpm, with Pb(II), Cd(II), and Cu(II) adsorption capacities of 1.913, 1.342, and 1.465 mg/g, respectively. Meanwhile, the optimum condition for HBA removal efficiency was achieved at an adsorbent dosage of 8.45 g, adsorption time of 5 h, and stirring speed of 150 rpm, resulting in Pb(II), Cd(II), and Cu(II) removal efficiencies of 32.612%, 28.390%, and 27.831%, respectively. Overall, HBM showed highest simultaneous adsorption performance compared with HBA in terms of both adsorption capacity and removal efficiency, whereas HBA exhibited a stronger adsorption tendency toward Pb(II). These findings demonstrate that biochar-based hydrogel composites derived from pineapple crown and avocado peel wastes can serve as promising alternative adsorbents for the treatment of heavy metal-contaminated water.