Zinc chloride is a commonly used activator in chemical activation of activated carbon. Various carbonaceous materials have been studied as potential source of activated carbon. The operating conditions are manipulated with attention to improve the properties and performance of activated carbon in the adsorption of water pollutants. However, the generalized attributes of zinc chloride activation in relation to the adsorptive performance of activated carbon are not well documented in much of published literature. Therefore, the present work is aimed to highlight the activation strategies and mechanisms of zinc chloride activation of activated carbon. The roles of impregnation ratio, period of activation and temperature are discussed to offer some insight into textural characteristics of activated carbon. The case studies on methylene blue adsorption are integrated to shed light on the external factors affecting the adsorption.

this work is aimed at evaluating the conversion of Pterocarpus indicus twigs into activated carbon via composite chemical activation for methylene blue and congo red dyes adsorption. the activated carbons were prepared by single-step chemical activation using zinc chloride and/or phosphoric acid at different mass impregnation ratios at 600 °C for 90 min. The activated carbons were characterized for textural properties and surface chemistry. The batch adsorption was investigated at different concentrations (5-1,000 mg/L), contact times (2-540 min) and temperatures (30-60 °C). Phosphoric acid-activated twigs carbon showed a high surface area of 1,445 m 2 /g with maximum methylene blue adsorption capacity of 438 mg/g. On the other hand, a composite-activated carbon yields a 217 mg/g of congo red removal. The adsorption data for both dyes fitted well with Langmuir and pseudo-second-order kinetics models, indicating the predominance of chemical adsorption through monolayer coverage of dye molecules on the homogenous surface of activated carbon. the thermodynamics properties of dye adsorption onto twigs-derived activated carbons indicated that the process is endothermic, spontaneous and favourable at high temperature. Overall, activated carbons derived from Pterocarpus indicus twigs could be effectively used for dye wastewater treatment. In many developing countries worldwide, textile industry is among the vast economy-driven activities with 2.8% rise in demand every year 1. However, it becomes a main contributor to water pollution issue that brings about multiple negative impacts to aquatic environment, ecological balance, and human health 2. The fabric sector consumes nearly several hundred thousand gallons of water every day, hence generating a large quantity of wastewater 3. Typical textile wastewater consists of nutrients such as phosphate, nitrates, micronutrients, and sources of carbon for algae cultivation 4. Yet, it also primarily includes colorants and auxiliary chemicals which are toxic and harmful, hence creating negative implications to the water streams 5. Dyestuff components are toxic, carcinogenic, and mutagenic. Generally, dye is persistent for a long duration because the molecular structure is complex and can withstand degradation by sunlight and microorganism in water. Additionally, dye in water can impede the penetration of sunlight, thereby reducing the rate of photosynthesis and consequently results in oxygen deficiency for respiration 6. Dyes can be categorized into anionic, cationic, and non-ionic. For example, methylene blue (basic blue 9) is among the prevalent cationic dyes used in the fabric sector and can cause damaging effects, primarily to the aquatic ecosystem and human health. Wastewater treatment strategies have been introduced to mitigate water pollution. Among others, adsorption outweighs other removal techniques because the process is simple, economical, and feasible for dye wastewater decontamination even at low concentration depending on the physicochemical properties of adsorbent...

No abstract

No abstract

Thermal plasma technique is becoming prominent in the treatment of variety of waste ranging from municipal solid waste, incinerator residue, hospital waste, electronics waste and industrial sludge. Application of the new treatment technology to petroleum sludge requires information on the nature and characteristics of the sludge that will be use to optimize the treatment system. In this investigation, petroleum sludge obtained from Petronas Melaka was characterized for its physical and chemical features. Proximate and ultimate analysis as well as determination of elemental composition were carried out. The sludge was found to contain high moisture (78.91%), low ash (5.06%), low volatiles (5.52%) and high fixed carbon (10.51%). The sludge has a TOC of 54.48% and HHV of 23.599MJ/kg. Despite the high moisture content, the higher heating value (HHV) is high when compared to literature values. The high value of HHV may be associated with the high fixed carbon, low ash content and high value of TOC. The apparent density of the sludge is slightly lower. Fourteen heavy metals are detected in significant quantities. Proper waste management that will safely dispose the sludge is required. The waste disposal technique should take into cognizant the possibility of leaching of heavy metals into ground water on one hand and the gasification of lighter ones as exhaust gas on the other.

This paper highlights the oil absorbing properties of natural and modified kapok fibres. The discussion is centred on the waxy layer and hydrophobic nature that translate the excellent oil removal performance of kapok fibre. A stirring had shown that the oil absorption by natural kapok could be greatly enhanced to over 200 g/g. For dispersed oil in wastewater, a depth filtrating system with rotatable and taper-shaped filter column with kapok fibre was reported to recover 32.3 g/g of the oils. Several modifications to boost the performance of kapok fibre as in acetylation, solvent treatment, fibre hybridization, assembly structure and design, etc. are identified and discussed to shed some light into future prospective in oil and emulsion removal. So far, all the studies have shown that kapok fibre and its modified counterparts are promising green oil absorbents. ARTICLE HISTORY

Membrane technology is important in industrial wastewater and water treatment. Recently, the polymeric membrane technology is widely chosen in these applications. However, they are lowtemperature ranges, low corrosion resistance, and low lifespan. Thus, researchers are actively trying to develop a better membrane technology such as natural clay ceramic membrane due to their excellent in chemical, mechanical and thermal resistance, high-pressure application and long lifespan. This detailed review compiles through the literature of current scientific research over the last ten years. Its highlights the key findings of factors in the fabrication of natural clay ceramic membrane that contributed to its properties. This review article presented an outline of the advantages, disadvantages, and how to overcome the disadvantages, structure, and preparation of ceramic membrane, including method, raw materials, drying and sintering temperature. The review confirmed that the sintering temperature, the composition of raw materials and pore-forming agent are significantly enhanced the mechanical strength and porosity of the natural clay ceramic membrane. However, further development and modification of the natural clay ceramic membrane technology and their applications to treat different environmental pollutants is still necessary.

The natural hollow fiber, namely kapok, has been studied for the removal of oil, particularly in the area of oil spill clean-up. The hydrophobic nature of the natural absorbent has been demonstrated to exhibit (or show potential to exhibit) excellent oil absorption properties. Kapok fiber is inexpensive, readily available, very lightweight which makes it easy for transportation and its excellent buoyancy eases retrieval. Reusability of the material up to 15 cycles has been reported and this supports its being environmental-friendly. This paper looks into the oil absorption capacity of raw kapok fiber that can be dramatically enhanced by the simple mechanism of stirring. The oil absorption capacity is greatly increased to more than 200 times the mass of kapok used, i.e., with stirring, 1 g of the kapok fiber is able to absorb at least 200 g of the oil (200 g/g) which in this case is the refined palm oil used for cooking. The paper also discusses the reasons for the improvement due to stirring. And as a natural agricultural product which is abundant, besides being environmental-friendly, its application would be a sustainable approach to control water pollution due to oil spills and industrial organic contaminants.