GENERATING A STREAM WITH A STABLE FORMALDEHYDE CONCENTRATION IN THE LABORATORY

A laboratory-scale bio-trickling filter (BTF) was initialized to evaluate the removal of formaldehyde biologically. However, generating formaldehyde gas in the lab is one of the grand challenges hindering research efforts. Formaldehyde was introduced into the gaseous phase by aerating the required air flowrate through a diluted formaldehyde solution mixed with methanol as a stabilizer by a bubbler. However, achieving stable gaseous influent concentrations of formaldehyde was challenging since it polymerizes while volatilizing. Resulting in paraformaldehyde. The resulting white powder clogged the pipes and generated uneven gaseous concentrations. To solve this problem, sodium hydroxide (NaOH) was added with a phosphate buffer to the aqueous formaldehyde solution to maintain the pH between 7.00-7.20. Additionally, the aqueous solution needed to be heated at 60℃ to eliminate the polymerization. The exhausted formaldehyde by volatilization was replaced by a continuous supply of aqueous diluted formaldehyde solution to keep the volume and mass of the aqueous solution and formaldehyde constant, respectively. Stable gaseous concentration was achieved for extended periods of time and verified by Fourier transform infrared (FTIR) spectroscopy.

Ruthenium catalyzed hydrogen production from formaldehyde–water solution

Efficient hydrogen production from aqueous formaldehyde with appreciably high TOF and TON achieved over an in situ generated ruthenium catalyst in water at 95 °C.

Biomimetic polydopamine catalyst with redox-activity for oxygen-promoted H2 production via aqueous formaldehyde reforming

We report for the first time that biomimetic polydopamine (PDA) nanoparticles are catalytically active for formaldehyde (HCHO) reforming into hydrogen (H2), where O2 acts as a co-catalyst. The catechol on...

Comparing Methods of Determining Formalin Concentration in Fluid Preservatives

Formalin (3.7% weight/weight [w/w], 4% weight/volume [w/v] aqueous formaldehyde) is commonly used as a fixative to prevent postmortem changes in the tissues of a specimen. The specimen is then either maintained in formalin or transferred to another fluid preservative, such as ethanol or isopropanol, for long-term preservation. Residual formalin often remains in the preservation fluid. As formaldehyde is a known carcinogen, it is important to know the concentration present in preservation fluids. A titration method has been developed to determine formalin concentration in fluid preservatives. It utilizes sodium sulfite to react with formaldehyde in solution. An adjustable, repeating pipette and a digital titrator allow for the rapid determination of formalin concentrations in small samples (<1 ml). This method of titration is compared with three commercially available methods of determining formaldehyde and formalin concentration: two brands of formaldehyde test strips, Quantofix® (Machery-Nagel GmbH) and MQuant® (EMD Millipore Corp), and a drop count titration test kit (Hach® formaldehyde test kit, model FM-1). A comparison and evaluation are made on the effectiveness of each method in determining the concentration of formalin in preservation fluids.

Sıntez poverhnostno-aktıvnyh veestv kondensatsıeı sýlfırovannyh fraktsıı pırolıznoı smoly s vodnymı rastvoramı formaldegıda [Synthesis of Surfactants by Condensation of Sulfonated Pyrolysis Resin Fractions with Aqueous Formaldehyde Solutions]

Optimal conditions for condensation of sulfonated naphthalene fraction with 40% formaldehyde aqueous solution are found. As a feedstock, a wide fraction (180–240°C) of the pyrolysis resin of hydrocarbon gases selected at the Atyrau processing plant was used. The chemical nature of the synthesized products, which by their properties resemble surfactants of the «necal» type, has been elucidated. It was shown that the synthesized products have well-pronounced surface-active properties and a floating ability in relation to Karatau phosphate ores. High-molecular water-soluble surfactants can also be used as flocculants in various types of water treatment. With their help, wastewater and process water, as well as drinking water are removed pollution in suspended state. Найдены оптимальные условия конденсации сульфированной нафталиновой фракции с 40%-ным водным раствором формальдегида. В качестве исходного сырья использовалась широкая фракция (180–240°С) смолы пиролиза углеводородных газов, отобранной на Атырауском НПЗ. Выяснена химическая природа синтезированных продуктов, которые по своим свойствам напоминают ПАВ типа «некалей». Показано, что синтезированные продукты обладают хорошо выраженными поверхностно-активными свойствами и флотирующей способностью по отношению к фосфатным рудам Каратау. Высокомолекулярные водорастворимые ПАВ могут применяться также как флокулянты в различных видах водоочистки. С их помощью из сточных и технологических вод, а также из питьевой воды удаляют загрязнения, находящиеся во взвешенном состоянии.

Pengawetan Ekstrak Zat Warna Alami dari Gambir (Uncaria gambir) dalam Pelarut Air

Abstrak. Tujuan penelitian ini adalah untuk menentukan jenis dan jumlah bahan pengawet yang secara efektif dapat menghambat reaksi biodegradasi zat warna alami dalam ekstrak gambir (Uncaria gambir) dalam pelarut air, serta menentukan nilai parameter reaksi biodegradasi zat warna alami dalam ekstrak gambir. Ekstrak zat warna alami dari gambir, yang telah bebas padatan, sebanyak 300 mL ditambah asam sitrat (0,006 gram/mL ekstrak) sebagai bahan bahan pengawet. Ekstrak kemudian disimpan dalam reaktor yang ditutup rapat dan dilindungi dari sinar ultra violet. Setiap selang waktu 2 hari, kadar pewarna alami dianalisis dengan metode gravimetri. Percobaan dilakukan dengan cara yang sama untuk 5 jenis pengawet lainnya dan dengan berbagai konsentrasi, yaitu: larutan formalin dalam air, larutan kitosan dalam asam asetat, ekstrak temu kunci (Boesenbergia rotunda L.), ekstrak daun salam (Syzygium polyanthum), dan ekstrak daun bandotan (Ageratum conyzoides L.), masing-masing sebanyak 5 mL larutan atau ekstrak bahan pengawet dalam 40 mL sampel ekstrak. Berdasarkan penelitian ini dapat ditetapkan bahwa larutan formalin dalam air dan larutan kitosan dalam larutan asam asetat 2% merupakan pengawet yang paling efektif menghambat reaksi biodegradasi zat warna alami dalam ekstrak, dibandingkan pengawet lainnya, yaitu: asam sitrat, ekstrak daun salam, ekstrak temu kunci, dan ekstrak daun bandotan. Jumlah formalin dan kitosan yang ditambahkan dalam ekstrak paling efektif berturut-turut adalah 0,017% dan 0,25% v/v. Nilai parameter reaksi biodegradasi zat warna alami dalam ekstrak diperoleh dalam bentuk konstanta kecepatan pertumbuhan spesifik (µ0, hari-1), konstanta saturasi (Ks, g/mL), konstanta kematian (kd, hari -1), rasio kd/µ0, dan yield (Yi). Kata kunci: biodegradasi, gambir, pengawet, pewarna alami. Abstract. Preservation of Natural Dye Extract from Gambir (Uncaria gambir) in Water as Solvent. The purpose of this study was to determine the type and the amount of preservative agent which effectively prevent biodegradation reaction of natural colorant in the aqueous extract of “gambir” (Uncaria Gambir). This study also determined the parameter values in the biodegradation reaction of gambir extract. The experiment was carried out by first preparing 300 mL of filtered gambir extract, into which citric acid as much as 0.006 g/mL was added as a preservative. The extract was then stored in a closed reactor with UV protector. Every two days, sample was drawn from the reactor for gravimetric analysis to determine the colorant concentration. Besides citric acid, the same experiments were also conducted for five other preservatives, which were the aqueous formaldehyde solution, the chitosan dissolved in 2% acetic acid solution, the extract of “temu kunci” (Boesenbergia rotunda L.), the extract of Indian bay leaf (Syzygium polyanthum), and the extract of “bandotan leaf” (Ageratum conyzoides L.). This study showed that aqueous formaldehyde solution and chitosan dissolved in 2% acetic acid solution was the most effective preservative to prevent biodegradation reaction of natural colorant in gambir extract, in comparizon to citric acid, “temu kunci”, Indian bay leaf, and “bandotan” leaf. The effective concentrations of formalin and chitosan were 0.017% and 0.25% v/v respectively. The parameters of the biodegradation reaction of the natural colorant in gambir extract in the form of specific growth rate coefficient (µ0, day-1), saturation constant (Ks, g/mL), death constant (kd, day -1), ratio of kd/µ0, and yield (Yi). Keywords: biodegradation, gambir, natural dye, preservative. Graphical Abstract

Hydroxymethylation of Furfural to HMF with Aqueous Formaldehyde over Zeolite Beta Catalyst

Hydroxymethylation of 2-furaldehyde (furfural) toward 5-hydroxymethyl-2-furaldehyde (HMF) was examined in this work among various zeolites with an aqueous formaldehyde as a reagent in a batch and a flow reactor system. It was found that the zeolite beta gave high activity and good reusability with calcination treatment before each run for the target reaction in the batch system. The unique stability of the HMF yield in the liquid-flow system was also observed only in the case of zeolite beta. The effect of the SiO2/Al2O3 ratio in the zeolite beta suggested that hydrophobicity would be an important factor in faster hydroxymethylation with an aqueous formaldehyde reagent. The highest turnover frequency (TOF) for HMF production was found to be 2.4 h−1 in the case of zeolite beta with SiO2/Al2O3 = 440 in the batch reactor system. An approximately 30% yield for HMF was achieved under optimum conditions for zeolite beta catalysts.