Gum rosin is an important agricultural commodity which is widely used as a raw material for various industries. However, gum rosin has low stability, crystallizes easily, and tends to oxidize. This is due to carboxyl groups and conjugated double bonds in gum rosin’s structure. Therefore, to reduce these weaknesses, it is necessary to modify the rosin compound to achieve better stability via the esterification process. This paper surveys esterification agents such as glycerol, pentaerythritol, methanol, ethylene glycol, polyethylene glycol (PEG), allyl group, and starch Rosin ester. The product is used in the manufacture of pressure-sensitive adhesives, drug delivery, solder flux for electronic devices, as a plasticizer, and as a coating agent in fertilizers. In general, the esterification reaction between alcohols and carboxylic acids is very slow without a catalyst. Heterogeneous catalysts have the advantage of controlling size, structure, spatial distribution, surface composition, thermal-chemical stability, and selectivity. Among the catalysts for gum rosin esterification are ZSM-5, Fe₃O₄, ZnO, Calcium, TiO₂, Kaolin, and Al₂O₃, among others. Different catalysts and esterification agents can produce various physical and chemical properties of rosin ester and will result in specific rosin ester products, such as glycerol ester, pentaerythritol ester, methyl ester, glycol ester, allyl ester, and acid starch-based rosin.

High Consumption of paper, bring the impact of the waste paper itself. And the utilization of the paper is limited to recycled products and crafts, whereas paper such as newspaper still contains cellulose that can be potential to be used as a heavy metal adsorbent. In this study, newspaper was dissolved in sodium bicarbonate to reduce various impurities and then was reacted with citric acid (CA). The modified adsorbent was characterized by FTIR and was tested for adsorb Cu(II) in artificial solution. After adsorption process, the solution was filtered and analysed using Atomic Absorption Spectrophotometer (AAS). The adsorption experimental data was fitted to Langmuir, Freundlich, Tempkin, and Dubinin-Radushkevich for equilibrium model and was fitted to pseudo first order reaction and pseudo second order reaction for kinetic studies. The result showed that CA-modification newspaper able to remove heavy metals Cu(II) in solution.

Korosi yang biasa disebut sebagai pengkaratan akibat terjadinya penurunan kualiatas mutu logam karena reaksi kimia suatu logam terhadap lingkungan disekitarnya. Banyak cara yang bisa dilakukan untuk memperlambat suatu laju reaksi pada korosi, seperti membuat paduan logam yang berfungsi agar tidak terjadi korosi, melapisi bagian logam agar tahan dari medium korosif, atau dengan cara membuat penambahan suatu zat yang berfungsi sebagai inhibitor penghambat korosi. Dalam penelitian ini dilakukan studi laju korosi dengan cara membuat penambahan zat yang berfungsi sebagai inhibitor dengan metode yang digunakan untuk mempelajari studi laju reaksi korosi adalah metode Gravimetri. Studi laju korosi ini bertujuan untuk mempelajari pengaruh inhibitor yang digunakan untuk penghambat korosi pada Aluminium. Data yang dihasilkan adalah menghitung massa benda uji sebelum dan setelah perendaman untuk dibandingkan. Hasil penelitian menunjukkan bahwa efisiensi inhibisi menghambat laju reaksi korosi Alumunium dalam larutan HCl berfungsi dengan nilai daya inhibisi 50 ppm inhibitor didapatkan pada waktu 5 menit 80.00%, 10 menit 77.06%, 15 menit 71.03%, 20 menit 62.17%, dan 25 menit 57.53% dengan laju korosi pada waktu 5 menit 0.0004, pada waktu 10 menit 0.0025, pada waktu 15 menit 0.0076, pada waktu 20 menit 0.01415 dan pada waktu 25 menit 0.02988.