Konversi Satu Langkah Minyak Sawit Bekas Menjadi Biodiesel Menggunakan Katalis Basa dari Cangkang Keong Sawah (Pomacea canaliculata) Teraktivasi Asam Tartarat
Friska Putri Normayanti, Prof. Dra. Wega Trisunaryanti, M.S., Ph.D.Eng.
2025 | Tesis | S2 Ilmu Kimia
Penelitian
ini telah berhasil memanfaatkan limbah pertanian lokal berupa cangkang keong
sawah (Pomacea
canaliculata) sebagai prekursor
katalis basa yang diaktivasi asam tartarat. Katalis ini diaplikasikan untuk produksi
biodiesel melalui konversi satu langkah dari minyak sawit bekas (MSB) dengan kandungan
asam lemak bebas (FFA) sebesar 2,87%. Penelitian bertujuan untuk mensintesis katalis
basa dari cangkang keong sawah teraktivasi asam tartarat serta mengoptimasi
proses produksi biodiesel menggunakan desain Central Composite Design (CCD) dalam Response Surface Methodology (RSM). Empat variabel bebas yang dioptimasi
meliputi
berat katalis (6-9%), rasio molar minyak terhadap metanol (1:6-1:12),
temperatur (55-70°C), dan waktu reaksi (4-6 jam).
Katalis CKS900/xTar
disintesis melalui kalsinasi pada temperatur 900°C selama 3 jam, kemudian
diaktivasi menggunakan asam tartarat (C4H6O6)
dengan konsentrasi 0,5 M; 1 M; dan 1,5 M. Seluruh katalis diuji performa
katalitik melalui konversi satu langkah MSB menjadi biodiesel menggunakan metode
refluks. Katalis hasil sintesis dikarakterisasi menggunakan SEM-EDX, XRD, XRF,
FTIR, NH3-TPD, CO2-TPD, dan surface area analyzer.
Hasil penelitian
menunjukkan CKS900/1Tar menghasilkan yield biodiesel tertinggi sebesar 50,76%. Aktivasi asam pada
katalis dapat meningkatkan luas permukaan hingga 29 kali lipat menjadi 13,6561
m2 g-1, memicu perubahan fase dari CaO menjadi Ca(OH)2
dan terbentuk senyawa kalsium tartarat tetrahidrat (CaC4H4O6?4H2O) dengan rasio kebasaan terhadap keasaman sebesar
0,3170. Optimasi CCD-RSM menghasilkan nilai R2 sebesar 0,9902 dan biodiesel
dengan yield sebesar 69,3% pada kondisi
berat katalis 7,5%, rasio mol minyak terhadap metanol 1:9, temperatur 62,5°C
dan waktu reaksi 5 jam. Uji reusability
menunjukkan katalis tetap aktif setelah lima siklus penggunaan ulang dengan yield biodiesel 52,3%. Validasi model
menghasilkan yield biodiesel optimum
sebesar 71% sebanding performanya dengan CaO900/1Tar yaitu 74,5%. Metil
ester dikonfirmasi menggunakan FTIR, GC-MS dan 1H NMR.
This study
successfully utilized agricultural waste in the form of golden apple snail shells (Pomacea
canaliculata) as a precursor for a base catalyst activated with
tartaric acid. The catalyst was applied for biodiesel production via one-step
conversion of used palm oil (UPO) with a free fatty acid (FFA) content of 2.87%.
This study aimed to synthesize a base
catalyst from golden apple snail shells activated by tartaric acid and to
optimize the biodiesel production process using Central Composite Design (CCD)
under Response Surface Methodology (RSM). Four process variables were
investigated: catalyst loading (6-9 wt%), oil to methanol molar ratio
(1:6-1:12), temperature (55-70°C), and reaction time (4-6 hours).
The
CKS900/xTar catalyst was synthesized by calcination at 900°C for 3
hours, followed by activation with tartaric acid (C4H6O6)
at concentrations of 0.5 M, 1 M, and 1.5 M. All catalyst were evaluated for
their catalytic performance via one-step conversion of UPO into biodiesel under
reflux conditions. The synthesized catalysts were characterized using SEM-EDX,
XRD, XRF, FTIR, NH3-TPD, CO2-TPD, and surface area
analysis.
The results
showed that CKS900/1Tar produced the highest biodiesel of 50.76%. Acid
activation significantly enhanced the surface area of the catalyst by uo to
29-fold, reaching 13.6561 m2 g-1, induced phase
transformation from CaO to Ca(OH)2, and facilitated the formation of
calcium tartrate tetrahydrate (CaC4H4O6?4H2O)
with a basicity-to-acidity ratio of 0.3170. Optimization using CCD-RSM yielded
an R2 of 0.9902 and achieved a biodiesel yield of 69.3% under
optimal conditions:7.5 wt.?talyst loading, a 1:9 molar ratio, 62.5°C
reaction temperature, and 5 hours of reaction time. Reusability tests indicated
the catalyst remained active after five reaction cycles, maintaining a yield
above 52.3%. Model validation produced an optimal yield of 71%, which is
comparable to the performance of commercial CaO900/1Tar 74.5%. Methyl
esters were confirmed by FTIR, GC-MS, and 1H NMR analyses.
Kata Kunci : cangkang keong sawah (Pomacea canaliculata), katalis basa teraktivasi asam tartarat, biodiesel, konversi satu langkah, RSM.
