ABSTRAK Pemahaman mengenai hubungan antara kestabilan dan proses ionisasi pada senyawa kompleks logam penting dalam pengembangan material fungsional dan sistem berbasis logam transisi. Penelitian ini bertujuan mengkaji pengaruh jumlah ligan NH3 terhadap kestabilan, sifat elektronik, dan karakteristik ionisasi kompleks [Ag(NH3)n] (n = 1–4) menggunakan metode Density Functional Theory (DFT). Optimasi geometri dilakukan untuk memperoleh struktur paling stabil, sedangkan analisis kestabilan dilakukan melalui energi pembentukan, energi stabilisasi, dan celah energi HOMO–LUMO. Karakteristik ionisasi dievaluasi menggunakan pendekatan AIP dan VIP dari hasil perhitungan optimasi dan frekuensi. Penelitian ini dilakukan secara komputasi dan perhitungan dilakukan dengan menggunakan basis set 6-3111++ G (d,p) untuk senyawa NH3, dan LANL2DZ ECP – B3LYP untuk unsur Ag & ion Ag+, dan untuk senyawa kompleks [Ag(NH3)n]+ (n=1-4) pada proses optimasi geometri. Sedangkan pada perhitungan opt+freq (optimasi dan frekuensi) untuk senyawa-senyawa kompleks [Ag(NH3)n] (n=1-4) dan [Ag(NH3)n]+ (n=1-4) digunakan basis set yang berbeda, yaitu SDD-ECP dengan fitting set DEF2SV. Hasil penelitian menunjukkan bahwa penambahan ligan NH3 meningkatkan kestabilan termodinamika kompleks, dengan [Ag(NH3)4] sebagai spesies paling stabil. Analisis HOMO–LUMO menunjukkan bahwa [Ag(NH3)2] memiliki kestabilan kinetik tertinggi. Nilai AIP dan VIP menurun secara bertahap seiring bertambahnya jumlah ligan, yang mengindikasikan peningkatan densitas elektron pada pusat logam Ag dan kemudahan pelepasan elektron. Hasil ini juga memberikan pemahaman yang lebih komprehensif mengenai peran ligan dalam mengatur kestabilan dan sifat elektronik kompleks perak–amonia, serta menjadi landasan teoritis bagi pengembangan material berbasis perak yang lebih efektif. ABSTRACT Understanding the relationship between stability and ionization processes in metal complexes is important for the development of functional materials and transition metal–based systems. This study aimed to investigate the effect of the number of NH3 ligands on the stability, electronic properties, and ionization characteristics of [Ag(NH3)n] complexes (n = 1–4) using Density Functional Theory (DFT). Geometry optimization was performed to obtain the most stable structures, while stability was evaluated through formation energy, stabilization energy, and HOMO–LUMO energy gap analyses. Ionization characteristics were assessed using Adiabatic Ionization Potential (AIP) and Vertical Ionization Potential (VIP) calculations based on optimized geometries and frequency analyses. Computational calculations were carried out using the 6-311++G(d,p) basis set for NH3 and the LANL2DZ effective core potential (ECP) combined with the B3LYP functional for Ag and Ag+ species during geometry optimization of the [Ag(NH3)n]+ complexes (n = 1–4). For geometry optimization and frequency calculations of neutral and ionized complexes, the SDD-ECP basis set with the DEF2SV fitting set was employed. The results showed that increasing the number of NH₃ ligands enhanced the thermodynamic stability of the complexes, with [Ag(NH3)4] exhibiting the highest stability. HOMO–LUMO analysis indicated that [Ag(NH3)2] possessed the greatest kinetic stability. Both AIP and VIP values decreased progressively with increasing ligand coordination, indicating higher electron density around the Ag center and a greater tendency for electron removal. These findings provide deeper insight into the role of ligands in governing the stability and electronic properties of silver–ammonia complexes and offer a theoretical basis for the development of more effective silver-based materials.
ABSTRAK Penelitian ini menguji efektivitas pati kulit singkong sebagai bioflokulan organik dalam pengolahan limbah kimia fenol dan p-klorofenol. Fokus utama studi adalah menganalisis pengaruh proses gelatinisasi, variasi dosis pati, serta durasi pengadukan terhadap efisiensi penurunan kadar polutan. Proses dimulai dengan isolasi pati lewat deproteinasi menggunakan larutan NaOH 0,5 M. Selanjutnya, flokulasi diuji pada 10 ml sampel limbah dengan memvariasikan dosis bioflokulan (0,2; 0,5; dan 1 gram) serta waktu pengadukan (15, 30, dan 60 menit). Hasil eksperimen membuktikan bahwa pati kulit singkong sangat efektif sebagai agen pengolah limbah. Kondisi operasional optimum tercapai pada dosis 0,5 gram dengan waktu pengadukan 30 menit, yang mampu mereduksi kadar fenol sebesar 85,32% dan p-klorofenol sebesar 84,32%. ABSTRACT This study evaluates the effectiveness of cassava peel starch as an organic bioflocculant for treating phenol and p-chlorophenol chemical wastewater. The primary focus of the study is to analyze the effects of the gelatinization process, variations in starch dosage, and stirring duration on pollutant reduction efficiency. The process began with starch isolation via deproteinization using a 0.5 M NaOH solution. Subsequently, flocculation was tested on 10 mL wastewater samples by varying the bioflocculant dosages (0.2, 0.5, and 1 g) and stirring times (15, 30, and 60 min). Experimental results demonstrate that cassava peel starch is highly effective as a wastewater treatment agent. The optimum operational conditions were achieved at a dosage of 0.5 g with a stirring time of 30 min, which reduced phenol and p-chlorophenol levels by 85.32% and 84.32%, respectively.
ABSTRAK Aktivitas antioksidan dan toksisitas ekstrak serta fraksi daun nilam (Pogostemon cablin Benth.) dari limbah penyulingan minyak nilam dievaluasi untuk mengetahui potensi senyawa bioaktif yang masih tersisa. Ekstraksi dilakukan dengan metode maserasi menggunakan etanol 96% dan dilanjutkan fraksinasi menggunakan n-heksana, etil asetat, butanol, serta air. Total fenolik, flavonoid, dan tanin dianalisis melalui spektrofotometri, sementara aktivitas antioksidan diuji dengan metode DPPH dan toksisitas menggunakan Brine Shrimp Lethality Test (BSLT). Hasilnya menunjukkan bahwa fraksi etil asetat memiliki kandungan fenolik (50,06 µg/mL), flavonoid (61,78 µg/mL), dan tanin (37,61 µg/mL) tertinggi dibandingkan dengan fraksi yang lain. Ekstrak dan semua fraksi yang diuji memperlihatkan aktivitas antioksidan dengan nilai paling besar ditunjukkan oleh frakse etil asetat. Uji toksisitas menunjukkan bahwa semua sampel bersifat toksik, dengan nilai LC₅₀ terendah pada fraksi etil asetat yaitu 233,82 µg/mL. ABSTRACT The antioxidant activity and toxicity of extracts and fractions from patchouli (Pogostemon cablin Benth.) leaves obtained from patchouli oil distillation waste were evaluated to determine the potential of remaining bioactive compounds. Extraction was carried out using the maceration method with 96% ethanol, followed by fractionation using n-hexane, ethyl acetate, butanol, and water. Total phenolic, flavonoid, and tannin contents were analyzed via spectrophotometry, while antioxidant activity was assessed using the DPPH method and toxicity was evaluated using the Brine Shrimp Lethality Test (BSLT). The results indicated that the ethyl acetate fraction exhibited the highest phenolic (50.06 µg/mL), flavonoid (61.78 µg/mL), and tannin (37.61 µg/mL) contents compared to the other fractions. The extract and all tested fractions demonstrated antioxidant activity, with the highest value observed in the ethyl acetate fraction. Toxicity testing revealed that all samples were toxic, with the lowest LC50 value found in the ethyl acetate fraction at 233.82 µg/mL.
ABSTRAK Telah dilakukan sintesis Zeolit Y secara hidrotermal berbasis pasir vulkanik Gunung Soputan. Hasil ekstraksi dan pengujian XRF menunjukkan ekstrak silika (SiO2) yang didapatkan dari pasir vulkanik Gunung Soputan memiliki kemurnian sebesar 92.37%. Pengujian karakterisasi dari Zeolit Y berdasarkan hasil XRD dan citra SEM menunjukkan munculnya peak pada 2θ = 6º, 10º, 15º, 23º, dan 27º dengan spesifik sudut 2θ = 6º [111] yang menunjukkan karakteristik Zeolite Y. Citra SEM menunjukkan tekstur permukaan material Zeolite Y yang cukup teratur dengan ukuran kristal 1-10 µm yang mengimplikasikan telah terbentuknya material Zeolit Y yang baik. Kemampuan Adsopsi dari Zeolit Y terhadap logam berat Pb pada variasi waktu kontak 40, 50, dan 60 menit, memiliki nilai masing-masing 79, 85,5, 93%. Kemampuan pemakaian kembali (lifetime) Zeolit Y yang didapat setelah tiga kali pemakaian. Menunjukkan kapasitas adsopsi Zeolit Y menurun. Kemampuan adsopsi setelah 3 kali pemakaian ulang yaitu sebesar 51%, 46,5%, dan 34,5% dengan nilai y = -1,65x + 12,1 dengan R² = 0,9356. ABSTRACT The synthesis of Y Zeolite was carried out hydrothermally using volcanic sand from Mount Soputan. The extraction and XRF testing results showed that the silica (SiO₂) obtained from the volcanic sand of Mount Soputan had a purity of 92.37%. Characterization tests of the Y Zeolite, based on XRD results and SEM images, revealed peaks at 2θ = 6º, 10º, 15º, 23º, and 27º, with specific angles at 2θ = 6º [111], which are characteristic of Y Zeolite. SEM images demonstrated a relatively regular surface texture of the Y Zeolite material with crystal particle sizes around 1-10 µm, indicating the formation of high-quality Y Zeolite material. The adsorption capacity of Y Zeolite for heavy metal Pb at contact times of 40, 50, and 60 minutes was 79%, 85.5%, and 93%, respectively. The reusability (lifetime) of Y Zeolite, after three cycles of use, showed a decrease in adsorption capacity. After three uses, the adsorption capacity was 51%, 46.5%, and 34.5%, with the regression equation y = -1,65x + 12,1 and R² = 0,9356.
ABSTRAK Telah dilakukan penelitian mengenai sintesis nanobiochar dari eceng gondok pada suhu pirolisis 550°C. Sampel serbuk dan non aktivasi suhu 550°C (nanobiochar-550) maupun nanobiochar aktivasi basa NaOH (nanobiochar-550-AB) dari eceng gondok yang dihasilkan dikarakterisasi menggunakan X-Ray Diffraction (XRD), Scanning Electron Microscope-Energy Dispersive X-Ray (SEM-EDX), Fourier-Transform Infrared Spectroscopy (FTIR). Hasil karakterisasi membuktikan terbentuknya nanobiochar dari eceng gondok. Kemudian, nanobiochar hasil sintesis dianalisis kemampuannya sebagai adsorben sianida. Berdasarkan hasil analisis menggunakan Spektofotometer uv-vis menunjukkan bahwa nanobiochar dari eceng gondok mampu bertindak sebagai adsorben. Hasil penelitian menunjukkan bahwa nanobiochar-550 mempunyai aktivitas absorpsi lebih besar dibandingkan nanobiochar-550-AB. Persentase adsorpsi ion sianida tertinggi untuk nanobiochar-550 yaitu waktu kontak 120 menit, dengan % adsorpsi sebesar : 93,0 % dan massa nanobiochar 0,1 gram. Sedangkan presentasi adsorpsi tertinggi untuk adsorben nanobiochar-550-AB juga berada pada menit ke-120 dengan persentase adsorpsi 89,0 % ABSTRACT Research has been conducted on the synthesis of nanobiochar from water hyacinth at a pyrolysis temperature of 550°C. Powder samples and non-activated samples at a temperature of 550°C (nanobiochar-550) as well as NaOH-activated nanobiochar (nanobiochar-550-AB) from water hyacinth were characterized using X -Ray Diffraction (XRD), Scanning Electron Microscope-Energy Dispersive X-Ray (SEM-EDX), and Fourier-Transform Infrared Spectroscopy (FTIR). The characterization results confirmed the formation of nanobiochar from water hyacinth. Subsequently, the synthesized nanobiochar was analyzed for its ability as a cyanide adsorbent. Based on the analysis results using a UV-Vis spectrophotometer, it was found that nanobiochar from water hyacinth is capable of acting as an adsorbent. The results showed that nanobiochar-550 has greater adsorption activity compared to nanobiochar-550-AB. The highest percentage of cyanide ion adsorption for nanobiochar-550 was at a contact time of 120 minutes, with an adsorption percentage of 93.0% and a nanobiochar mass of 0.1 grams. Meanwhile, the highest adsorption percentage for the nanobiochar-550-AB adsorbent was also at 120 minutes with an adsorption percentage of 89.0%.
