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In this study, thermophilic biohydrogen production by a mixed culture, obtained from a continuous acidogenic reactor treating palm oil mill effluent, was improved by using granular activated carbon (GAC) as the support material. Batch experiments were carried out at 60 C by feeding the anaerobic sludge bacteria with a sucrose-containing synthetic medium at an initial pH of 5.5 under anoxic conditions. The physico-chemical characteristics of the attached biofilm were evaluated after extraction of the extracellular polymeric substances (EPSs) of the biofilm using the formaldehyde-NaOH method. The main component of the biofilm was protein (60%), while the carbohydrate content accounted for 40% of the EPS. Two major absorption bands at approximately 3400 cm À1 and 1650 cm À1 , characteristics of the stretching vibrations of hydroxyl and amino groups, respectively, were identified in the FT-IR spectra, confirming the composition of the EPS. Observations using scanning electron microscopy (SEM) illustrated the attachment of rod-shaped bacterial cells on the GAC at 60 C. A maximum hydrogen production rate of 4.3 mmol L À1 h À1 and a hydrogen yield of 5.6 mol H 2 per mol sucrose were obtained from this attached biofilm system. The major soluble metabolites of fermentation were acetic acid and butyric acid. The results showed that the granular activated carbon enhanced the biohydrogen production by stabilizing the pH and microbial metabolites and therefore could be used as a support material for fermentative hydrogen production under thermophilic conditions on a large scale. Fig. 2 Batch kinetics of hydrogen production from sucrose with GAC-attached biofilm at 60 C and initial pH of 5.5. (a) Gompertz curve-fitting graph of cumulative gas production and (b) composition of soluble metabolites (acetic acid -HAc, butyric acid -HBu and ethanol -EtOH) and sugar consumption.19386 | RSC Adv., 2015,5,[19382][19383][19384][19385][19386][19387][19388][19389][19390][19391][19392] This journal is

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The theme of present research demonstrates performance of copper (II) sulfate (CuSO) as catalyst in thermolysis process to treat reactive black 5 (RB 5) dye. During thermolysis without presence of catalyst, heat was converted to thermal energy to break the enthalpy of chemical structure bonding and only 31.62% of color removal. With CuSO support as auxiliary agent, the thermally cleaved molecular structure was further destabilized and reacted with CuSO. Copper ions functioned to delocalize the coordination of π of the lone paired electron in azo bond, C=C bond of the sp carbon to form C-C of the sp amorphous carbon in benzene and naphthalene. Further, the radicals of unpaired electrons were stabilized and RB 5 was thermally decomposed to methyl group. Zeta potential measurement was carried out to analyze the mechanism of RB 5 degradation and measurement at 0 mV verified the critical chemical concentration (CCC) (0.7 g/L copper (II) sulfate), as the maximum 92.30% color removal. The presence of copper (II) sulfate catalyst has remarkably increase the RB 5 dye degradation as the degradation rate constant without catalyst, k is 6.5224 whereas the degradation rate constant with catalyst, k is 25.6810. This revealed the correlation of conversion of thermal energy from heat to break the chemical bond strength, subsequent fragmentation of RB 5 dye molecular mediated by copper (II) sulfate catalyst. The novel framework on thermolysis degradation of molecular structure of RB 5 with respect to the bond enthalpy and interfacial intermediates decomposition with catalyst reaction were determined.

The objective of this study is to investigate the fire retardancy effect of coconut coir, rice husk and sawdust panels which are incorporated with magnesium hydroxide (Mg (OH)2) and zinc borate (2ZnO∙3B2O3∙3.5H2O) as additives. The natural fiber and additives are mixed and cured for one week, with polyester resin and hardening catalyst as binders. Fire retardancy of these panels are tested according to American Society for Testing and Materials (ASTM) Horizontal (D 365) and Vertical Burning (D 3801) tests. Principle of fire retardants and mechanism of polymer combustion are shown in this study too. The study revealed that the sawdust panels with both additives have the highest fire retardancy compared to rice husk and coconut coir panel with both additives.

Photocatalytic degradation performance is highly related to optimized operating parameters such as initial concentration, pH value, and catalyst dosage. In this study, the impact of various parameters on the photocatalytic degradation of anaerobically digested vinasse (AnVE) has been determined through decolourization and chemical oxygen demand (COD) reduction efficiency using zinc oxide (ZnO) photocatalyst. In this context, the application of photocatalytic degradation in treating sugarcane vinasse using ZnO is yet to be explored. The COD reduction efficiency and decolourization achieved 83.40% and 99.29%, respectively, under the conditions of 250 mg/L initial COD concentration, pH 10, and 2.0 g/L catalyst dosage. The phytotoxicity assessment was also conducted to determine the toxicity of AnVE before and after treatment using mung bean ( Vigna radiata ). The reduction of root length and the weight of mung bean indicated that the sugarcane vinasse contains enormous amounts of organic substances that affect the plant's growth. The toxicity reduction in the AnVE solution can be proved by UV–Vis absorption spectra. Furthermore, the catalyst recovery achieved 93% in the reusability test. However, the COD reduction efficiency and decolourization were reduced every cycle. It was due to the depletion of the active sites in the catalyst with the adsorption of organic molecules. Thus, it can be concluded that the photocatalytic degradation in the treatment of AnVE was effective in organic degradation, decolorization, toxicity reduction and can be reused after the recovery process. Graphical abstract

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