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With the development of society, pollution accidents occur more frequently, and the effects of toxic substances containing silver on human health and environment are increasingly extensive. Therefore, the real-time on-site monitoring of silver ions is urgently needed. Based on the catalase-like properties of graphene/nano-platinum composites and the coupling effect between Pt and Ag+, a simple, unlabeled colorimetric sensing method is proposed to achieve the quantitative detection of Ag+. Under optimal conditions, the detection range of Ag+ by this colorimetric sensing method is 0.5–1000 μM, and the detection limit is 0.5 μM, which is lower than the previously reported detection limit of unlabeled Ag+ colorimetric sensing method, showing higher sensitivity and detection range. Under the same conditions, the sensor has almost no response to interference ions, showing good specific recognition ability. In addition, the colorimetric sensing method can be used to detect Ag+ in actual water samples, serving as a new paradigm for visual detection of Ag+. [ABSTRACT FROM AUTHOR]

The characteristics of catalysts impregnated in coconut shell (CS) and palm kernel shell (PKS) activated carbon were determined as potential precursors of catalysts used in a flue gas denitrification system at low temperature. In this study, Manganese (Mn) and Copper (Cu) with metal loading of 8% were impregnated in the activated carbon (AC) before undergoing low temperature calcination process. The morphological properties of samples was analysed using Scanning Electron Microscopy (SEM) and Brunauer, Emmett and Teller (BET) was used to determine the surface area and pore size of samples. The exhaust gas from a diesel engine at a constant flow rate of 4L/min was passed through in a fixed-bed catalytic reactor containing the catalyst, and the concentration of NOx was measured for temperatures ranging from 150°C to 250°C. It was found that the CS catalysts (CS-Mn and CS-Cu) and PKS catalysts (PKS-Mn and PKS-Cu) have the potential to reduce NOx concentration, and results showed that the metal loading of 8% resulted NOx reduction ranging from ~48% to 64%.

Adsorption is an effective way of extracting heavy metal ions from aqueous solutions. Alkali treatment is a chemical modification method that is influenced by concentration and time. The study aims to investigate the effect of NaOH treatment of OPEFB on Cd (II) adsorption under acidic condition. The alkali treatment was done by varying the concentration of NaOH (0.1 M, 0.5 M, and 1.0 M) and the immersion time (12 h and 24 h). SEM images confirmed the existence of pores on the treated OPEFB in comparison with the raw OPEFB. Characterization of treated adsorbent using FTIR resulted in a change of functional groups peak's position such as hydroxyl and carboxyl groups after the alkali treatment, which might involve Cd (II) adsorption. OPEFB treated with 1.0 M NaOH and 24 h immersion time showed the highest Cd (II) removal under acidic condition (pH 4). All the NaOH treated OPEFB showed an increment in adsorption efficiencies compared to raw OPEFB, suggesting that this treated biomass has a potential for application as an adsorbent for the removal of Cd (II) from wastewater. [ABSTRACT FROM AUTHOR]

Serious water pollution due to climate change as the consequences of non-ecological wastewater treatment and unsustainable agricultural activities had emerged water scarcity problem. The utilization of oil palm biomass into cadmium adsorbent could play a role in killing two birds with one stone, which is to solve the oil palm biomass disposal issue and cadmium pollution issue. The adsorbent modifications discussed in this review focused on furnace heating and microwave heating as well as the combined methods with chemical activating agents. Among the modification methods, the output of chemical activation followed by microwave-induced irradiation of palm kernel shells (PKS) produced activated carbon with high specific surface area (854.42 m2/g) and high adsorption capacity, qmax (227.27 mg/g). This review is to provide a comprehensive understanding of cadmium adsorption mechanisms and up-to-date progress of modification technologies for different types of oil palm biomass. [ABSTRACT FROM AUTHOR]

In many developing countries, domestic greywater remains as a large contributor of organic pollution in rivers. Considering rivers as the main source of freshwater, the level of pollution need to be minimized by pre-treating the domestic greywater from residential areas prior to release into the drains and rivers. With the need of this pre-treatment process and the economic burden to install current technologies, it is hence necessary to develop a more low-cost wastewater treatment system. Utilizing agriculture wastes as the bio-filter media in the greywater treatment system is one of the possible options to reduce the cost of treatment and accumulation of agricultural wastes. Therefore, this study focuses on the performance of agricultural wastes; coconut coir and rice husk, as low-cost packing media and biofilm material carrier for domestic greywater treatment. The performance of these media were evaluated based on the removal efficiencies of BOD5 and COD from the wastewater samples. The results have shown that there were insignificant differences in the performance of both media in removing BOD5 and COD, such that the removal efficiencies achieved by coconut coir media were 43.93% and 38.19% respectively, whilst the later recorded removal efficiencies of 42.42% and 34.85% respectively. [ABSTRACT FROM AUTHOR]

Zirconium-based ferromagnetic sorbent was fabricated by coprecipitation of Fe2+/Fe3+ salts in a zirconium solution and explored as a potential sorbent for removing the Cu2+, Zn2+, and Cd2+ from aqueous solution. The sorbent could easily be separated from aqueous solution under the influence of external magnetic field due to the ferromagnetism property. A trimodal distribution was obtained for the sorbent with average particle size of 22.74 μm. The –OH functional groups played an important role for efficient removal of divalent ions. The surface of the sorbent was rough with abundant protuberance while the existence of divalent ions on the sorbent surface after the sorption process was demonstrated. Decontamination of the heavy metal ions was studied as a function of initial metal ions concentration and solution pH. Uptake of the heavy metal ions showed a pH-dependent profile with maximum sorption at around pH 5. The presence of the ferromagnetic sorbent in solution at different initial pH has shown a buffering effect. Equilibrium isotherms were analyzed using Langmuir, Freundlich, Dubinin-Radushkevich, and Temkin isotherm models. Adequacy of fit for the isotherm models based on evaluation of R2 and ARE has revealed that heavy metal ions decontamination was fitted well with the Freundlich model. [ABSTRACT FROM AUTHOR]