Chemical Engineering

In this study, ultrafiltration membrane for humic substance removal was prepared by blending polysulfone with high concentration of PEG400 as additives. The influences of the additive to the fouling resistance capability and humic substances rejection of the polysulfone membrane were investigated. The addition of 35%wt of PEG400 concentration improved pure water flux up to 200, but resulted in higher fouling resistance of humic substances. High concentration of PEG400 increased irreversible fouling and significantly reduced the flux recovery ratio of the membrane. More than 80% humic substances rejection is achieved when a high concentration of PEG400 was added into membrane solution.

olysulfone-based membrane has been used in hemodialysis (HD) and it is continuously developed to maintain its sustainability on the subject of biocompatibility. During the polysulfone-based membrane development, several parameters should be considered to improve the membrane performances, such as excellent biocompatibility, appropriate ultrafiltration rate, and effective clearance of target solute. In term of biocompatibility, characteristic of interaction between protein in blood and membrane surface is a critical point of view to avoid platelet adhesion and activation that initiate the inflammatory responses. Different methods of modifications have been proposed. Most of the modification methods are focused on the increase of membrane hydrophilicity. A number of modified polysulfone-based membranes have been developed through several methods including blending materials, plasma treatment, and other surface modifications. Selectivity of the polysulfone membrane also plays an important role to avoid endotoxin leakage and reduce albumin loss during HD treatment. On the other hand, sterilization of HD membrane also becomes very important with regard to their effects, such as changes in physicochemical properties, biocompatibility, and performances of the membranes. In this paper, the polysulfone-based membrane for HD is reviewed comprehensively. Special attention is given to the preparation, characterization and sterilization of HD membranes

Recently, ultrafiltration membrane technology is challenged to maintain their sustainability and favourable economics by improving their flux, selectivity and durability.  Polysulfone membrane constitute the most extensively studied class of membrane materials due to its commercial availability, excellent chemical and thermal resistance, good mechanical properties and easy processing. However, polysulfone ultrafiltration membrane is susceptible to fouling and has low permeate flux due to hydrophobicity properties of the materials. Membrane modifications become unavoidable in order to reduce the fouling susceptibility. One simple and attractive method is blending polysulfone with additives. Previous studies show that the addition of additives in membrane solution could enhance membrane performances with higher porosity and flux. Meanwhile in surface water treatment application, humic substance has brought particular interest due to its nature which could produce some carcinogen substances that have negative effects on the human health in long term period. Therefore, the investigation to remove humic substances is considered as a sustainable solution in the field of surface water treatment. Many studies have been conducted with polysulfone based ultrafiltration membrane to remove humic substance from water, thus the factors that influenced humic substances fouling on polysulfone-based membrane and the effect of additive concentration on the improvement membrane performance for humic substance removal will be reviewed further in this paper.

Telah dipelajari tentang pengaruh kekristalan plastik pada plastik tak berkristal (polystyrene) dan
berkristal (polypropylene) terhadap struktur foam plastik mikroselular. Blowing agent yang digunakan adalah
fluida karbon dioksida dan nitrogen superkritis. Proses dilakukan pada temperatur tinggi dan tekanan konstan
17 MPa dengan proses batch. Didapatkan bahwa struktur sel mikroselular pada masing-masing jenis plastik
berbeda. Hasil tersebut dipengaruhi oleh kelarutan blowing agent dalam plastik, seperti yang dijelaskan oleh
peneliti-peneliti terdahulu. Didapatkan bahwa temperatur yang dibutuhkan untuk pembetukan sel dalam plastik
non-kristal lebih rendah dibandingkan plastik berkristal. Selain jenis plastik, juga diteliti tentang pengaruh jenis
blowing agent yang digunakan terhadap struktur sel yang dihasilkan pada plastik mikroselular. Pada plastik tak
berkristal, densitas sel semakin menurun dan diameter sel semakin meningkat dengan naiknya temperatur
hingga 433 K. Diatas temperatur tersebut terjadi sebaliknya. Sedangkan pada plastik berkristal, sel
mikroselular baru terbentuk pada temperatur mulai dari 443 K. Dibawah temperatur tersebut, belum terbentuk
sel yang disebabkan oleh meningkatnya kekristalan plastik dengan naiknya temperatur penjenuhan/pemenasan

Di dalam pengolahan secara biologis, bakteri dan mikroorganisme yang lain akan memecah dan memetabolisme zat organik terlarut, oleh karena itu dapat mengurangi BOD dan COD. Namun tidak semua organik terdegradasi, waktu yang cukup dan jenis mikroba yang sesuai akan membantu degradasi zat organik lebih banyak lagi. Pengolahan secara biologis pada umumnya adalah aerobik dan anaerobik. Proses secara Aerobik Proses secara aerobik terjadi reaksi biokimia untuk pertumbuhan dan metabolisme bakteri/mikroba lainnya. Agar proses berjalan lancar, cell-cell harus tumbuh berkembang lebih cepat dari yang dioksidasi (hal ini yang menghasilkan lumpur). Reaksi pada proses aerobik lumpur aktif : Organik terlarut + O 2 + N + P F 0 E 0 cell + CO 2 + H 2 O + NO 3 sisa organik terlarut yang tak terurai Proses aerobik dengan aerasi juga dimaksudkan untuk menghilangkan komponen organik yang mudah menguap. Di samping itu cell mikroba memerlukan nutrient. Proses secara Anaerobik Denitrifikasi adalah proses biologis anaerobik, digunakan untuk mengkonversi nitrogen-nitrat dalam effluent dari proses nitrifikasi lumpur aktif menjadi gas nitrogen. Nitrat merupakan reduktor maka kandungan nitrat dalam air sangat berbahaya sehingga harus dikurangi atau dihilangkan. Bakteri yang berperan dalam denitrifikasi umumnya merupakan bakteri anaerobik. NO3-+ Substrate N2 + CO2 + H2O + OH-+ cells

Salah satu disiplin ilmu yang penting untuk dikuasai agar seseorang bisa memahami dan menafsirkan Al-Qur’an dengan baik dan benar adalah ilmu tentang waqf dan ibtidā’. Para ahli Al-Qur’an merumuskan dan menyusun teori-teori tentang waqf dan ibtidā’ yang kemudian dicantumkan dalam Mushaf Al-Qur’an dengan tanda-tanda tertentu untuk memudahkan para pembaca Al-Qur’an terutama orang ‘Ajam. Fakta nya terdapat keragaman tentang tanda-tanda waqf, dalam Mushaf Standar Indonesia dan Mushaf Madinah. Apakah keragaman tersebut mempengaruhi penafsiran? Tulisan ini mencoba memberi jawaban sehingga upaya ini diharapkan dapat menjadi khazanah intelektual yang memperkaya pemahaman umat.Kata kunci: waqf dan ibtidā’ , Mushaf Standar Indonesia dan Mushaf Madinah, keragaman, khazanah intelektual