Studi Model Kinetika Ekstraksi Berbantu Ultrasonik pada Lada (Piper nigrum L.)

Ultrasonic Assisted Extraction (UAE) digunakan untuk mengekstraksi oleoresin dari lada yang memberikan metode yang lebih kompetitif dibandingkan dengan metode maserasi. Penelitian ini bertujuan untuk mempelajari dan melakukan validasi model orde kedua dari model kinetika ekstraksi berbantu UAE pada lada putih yang dapat menggambarkan hubungan antara rendemen oleoresin, amplitudo UAE dan waktu ekstraksi. Biji lada digiling hingga memiliki ukuran partikel sebesar 100 mesh. Ekstraksi UAE dilakukan dengan menambahkan 200 g bubuk lada ke dalam 800 ml etanol (1:4). Proses maserasi juga dilakukan sebagai perlakuan kontrol. Amplitudo dan waktu ekstraksi yang digunakan dalam ekstraksi berrbantu UAE adalah 45, 60, 75, dan 90 %; dan 45, 60, 75, dan 90 menit. Nilai eksperimen konsentrasi oleoresin lada putih (Ct) dan perhitungan model sangat berkaitan dengan kapasitas ekstraksi saat saturasi (Cs) dan konstanta laju ekstraksi (k). Nilai Cs berkisar antara 29,24–34,48 g/l dan nilai k berkisar antara l/g.menit. Perolehan hasil dari kedua Ct menghasilkan nilai koefisien korelasi sebesar 0,85 dan nilai galatnya pada perhitungan model berkisar antara 0,18–14,09 %. Model kinetik orde kedua yang dikembangkan dapat digunakan untuk memprediksi hasil rendemen oleoresin lada putih berbantu UAE dengan kondisi batas amplitudo UAE 45–90 % dan waktu ekstraksi 45–90 menit.

Removal of wood extractives as pulp (pre-)treatment: a technological review

Wood extractives usually do not exceed five percent of dry wood mass but can be a serious issue for pulping as well as for the pulp itself. They cause contamination and damages to process equipment and negatively influence pulp quality. This paper addresses not only the extractives-related problems but also different solutions for these issues. It is an extensive review of different technologies for removing wood extractives, starting with methods prior to pulping. Several wood yard operations like debarking, knot separation, and wood seasoning are known to significantly decreasing the amount of wood extractives. Biological treatment has also been proven as a feasible method for reducing the extractives content before pulping, but quite hard to handle. During pulping, the extractives reduction efficiency depends on the pulping method. Mechanical pulping removes the accessory compounds of wood just slightly, but chemical pulping, on the other hand, removes them to a large extent. Organosolv pulping even allows almost complete removal of wood extractives. The residual extractives content can be significantly reduced by pulp bleaching. Nevertheless, different extraction-based methods have been developed for removing wood extractives before pulping or bleaching. They range from organic-solvent-based extractions to novel processes like supercritical fluid extractions, ionic liquids extractions, microwave technology, and ultrasonic-assisted extraction. Although these methods deliver promising results and allow utilization of wood extractives in most cases, they suffer from many drawbacks towards an economically viable industrial-scale design, concluding that further research has to be done on these topics. Graphical abstract

The Leaching of Natural Dyes from Avocado (Persea Americana Mill) Seeds Using the Ultrasonic-Assisted Extraction Method and Its Application to Cellulose Fibers

The textile industry uses synthetic dyes because they are cheaper and easier to obtain. Moreover, the color availability is guaranteed and more varied. However, these synthetic dyes have a negative impact on health and the environment. The natural dye from avocado (Persea Americana Mill) seeds can become an alternative for synthetic dyes. Polyphenol compounds, such as tannins and flavonoids, are natural color sources found in avocado seeds. The extraction of natural dyes from avocado seeds is carried out by using a non-conventional method, namely ultrasonic-assisted extraction which has great efficiency and short operating time. In this study, researchers examined the parameters that affect the yield of dye extraction from avocado seeds, namely solvent concentration and extraction time. In addition, researchers also conducted qualitative analysis on the pigment content in the yield of extraction using UV-Visible Spectrophotometry and GC-MS tests. The results indicated that the highest yield obtained from avocado seeds was 16.6742% with 90 minutes extraction time using 70% ethanol solvent. Furthermore, if the dye is applied to cellulose fibers, such as the cotton cloth, the color will change depending on the fixator added. Based on the result of the UV-Visible Spectrophotometry test, the avocado seeds contain flavonoids. Meanwhile, from the result of the GC-MS test, the compound with the largest percentage detected in avocado seeds is the 13-Tetradecynoic acid, methyl ester (C15H26O2). The compound contains a chromophore, such as a carbonyl group (C = O) which is a common feature of flavonoids.