Mohd Firdaus Yhaya

Impacts of trace element supplementation on the performance of anaerobic digestion process: A critical review

This paper critically reviews the impacts of supplementing trace elements on the anaerobic digestion performance. The in-depth knowledge of trace elements as micronutrients and metalloenzyme components justifies trace element supplementation into the anaerobic digestion system. Most of the earlier studies reported that trace elements addition at (sub)optimum dosages had positive impacts mainly longer term on digester stability with greater organic matter degradation, low volatile fatty acids (VFA) concentration and higher biogas production. However, these positive impacts and element requirements are not fully understood, they are explained on a case to case basis because of the great variance of the anaerobic digestion operation. Iron (Fe), nickel (Ni) and cobalt (Co) are the most studied and desirable elements. The right combination of multi-elements supplementation can have greater positive impact. This measure is highly recommended, especially for the mono-digestion of micronutrient-deficient substrates. The future research should consider the aspect of trace element bioavailability.

Utilisation of natural cellulose fibres in wastewater treatment

Water safety and security are global problems. Indeed, researchers have taken this matter seriously and have begun to find alternative ways of treating wastewater. The conventional method for treating wastewater has been found to be uneconomical, and the polymeric materials used were not environmentally friendly. Biosorption techniques and mechanisms have been shown to be an effective alternative to replace conventional technologies. As agricultural waste is abundantly available, it has been chosen as the best starting material to produce biosorption material. Also, the hydroxyl functional groups in cellulose act as important parts to produce better absorbent materials. This review has explored the role of natural fibres as adsorbents for wastewater treatment while at the same time, for the removal of adsorbates such as oil, dyes, heavy metals, ionic compounds, and others as reported in the literature. Also investigated in this study, were the different modification types used to enhance the fibres and the mechanism of contaminant removal by the absorbents. Lastly, the physical forms of adsorbates and common types of effluents treated using natural fibres were examined and discussed.

Polymeric Heat Exchangers: Effect of Chemistry and Chemical Composition to Their Performance

Polymers can be used to construct heat exchangers, provided the polymer selection and design are done correctly. Despite their limitations, many types of thermoplastic polymers (thermoplastics) are being used as heat exchangers as compared to thermosetting polymers (thermosets). Properties of polymers are by large influenced by their chemical compositions and molecular weight. Based on current trends, the future outlook for polymers as heat exchangers is bright.

Challenges, Future Outlook, and Opportunities

Nocturnal cooling technology has the characteristics of cleanness, pollution-free, energy savings and great development potential. Throughout the literature, it can be seen that the nocturnal cooling technology has become a research hotspot since 1960s. Early researches were mainly concentrated in optimising the structure of radiation cooling systems and improving the radiation cooling capacity. The last recent years have witnessed exceptional achievements in nocturnal cooling approach, with a huge body of literature consisting of more excellent performance studies related to hybrid systems; improvement and advancement on the technological aspects of existing and previous works as well as design and applications of the system within building envelope. Nocturnal cooling systems are directly affected by the atmospheric conditions. The performance studies of these systems are widely distributed and various climatic conditions and regions. However, most of the studies are conducted under laboratory scale and not many studies focus on the performance of the systems on real or existing buildings towards commercialisation. In this chapter, challenges, future outlook and opportunities are highlighted.

Renewable and Sustainable Materials for Various Green Technology Applications

In the recent years, the environmental issues in terms of pollution and energy consumption foment an increasing interest to focus on green technology. Pertaining this, this chapter is intended to recapitulate a review on renewable and sustainable materials produced either from single unit process or integrated approach through chemical or biological methods or combination of these methods for various green technology applications. This includes the recent development and potential of these materials for energy, building and environmental applications.

Renewable and Sustainable Materials from Chemical Approach

Despite the negative connotations associated with the word ‘chemistry’, in reality many chemical principles and processes are used to develop renewable and sustainable materials. In order to do so, a wide selection of organic materials is readily available. Application of these ranges from renewable energy to advanced materials. In the near future, it is expected that chemistry for sustainability would become the new mantra in the world of ever-limited resources. This chapter presents a detailed discussion on chemistry and chemical approach of these materials. It is hoped that in the near future, chemistry for sustainability would become the new mantra in the world of ever-limited resources.

The Effect of Glycidyl Silane as Coupling Agent in Intumescent Flame Retardant System

The effect of different carbonizing agents; ethylene glycol, glycerol, and pentaerythritol to the char formation were studied in this research. After burning process, formulation with ethylene glycol, glycerol, and pentaerythritol showed chars thickness of 10 mm, 32 mm, and 45 mm. The chars’ strength at peak force was recorded at 3.20 N, 7.75 N, and 9.48 N while the burning rate of each sample were 5.23 x 10-4 mm/s, 4.20 x10-4 mm/s, and 6.24 x10-4 mm/s respectively. Formulation with glycerol as carbonizing agent showed the lowest burning rate as compared to the other formulations. Additional formulation with glycidyl silane as coupling agent in glycerol formulation was also studied. The formation of chemical bonding between silane, glycerol, and epoxy glycerol was confirmed by Fourier Transform Infrared (FTIR) absorption peak at 767.25 cm-1. The burning rate was 1.44 x 10-5 mm/s after silane treatment. Thermal degradation of the silane-treated resin started at 220°C as measured by thermogravimetric analysis (TGA).