Fabrication of chitosan microspheres for efficient adsorption of methyl orange

In this article, morphology, structure and size controllable chitosan microspheres with high mechanical strength were synthesized by microfluidic technology combining chemical crosslinking and used as an adsorbent for methyl orange. The synthesized adsorbents were characterized using scanning electron microscopy(SEM),Fourier transform infrared spectroscopy(FTIR), and an Energy Dispersive Spectrometer(EDS). The effect of pH revealed that the adsorption process depended on pH and the pH variation of methyl orange solution after adsorption indicated that adsorption capacity was affected through the associated role of chitosan nature and pH variation. Experimental results suggested that the as-prepared chitosan microspheres were controlled within a narrow size distribution(coefficients of variation is 1.81%), whose adsorption capacity reached to 207 mg·g^(-1) and mechanical strength was suitable to resist forces. In addition, the adsorption isotherm was well fitted with the Langmuir model, and the adsorption kinetic was best described by the pseudo-second-order kinetic model.The high performance microfluidic-synthesized chitosan microspheres have promising potentials in the applications of removing dyes from wastewater.

Design and Technical Development of Wall-Climbing Robots:A Review

Once working at heights is dangerous,it is a significant accident.These accidents brought substantial economic losses and caused a large number of casualties.Therefore,it is essential to use wall-climbing robots to replace manual work at heights.The design of the wall-climbing robot is inspired by the climbing action of insects or animals.An intelligent bionic robot device can carry special equipment to operate on the wall and perform some dangerous operations instead of firefighters or inspection personnel more efficiently.The scope of application is vast.This paper firstly summarizes the research progress of wall-climbing robots with three different moving methods:wheel-climbing,crawler-based,and leg-footed robots;summarizes the applications and breakthroughs of four adsorption technologies:negative pressure,magnetic force,bionic and electrostatic;discusses the application of motion control algorithms in wall-climbing robots.Secondly,the advantages and disadvantages of different migration modes and adsorption methods are pointed out.The distribution and advantages of the combined application of different migration modes and adsorption methods are analyzed.In addition,the future development trend of wall-climbing robots and the promoting effect of bionic technology development on wall-climbing robots are proposed.The content of this paper will provide helpful guidance for the research of wall-climbing robots.

Microfluidic synthesis of thiourea modified chitosan microsphere of high specific surface area for heavy metal wastewater treatment

An improved biosorbent of thiourea modified chitosan microsphere（TMCM） with high specific surface,favorable mechanical strength and excellent adsorption performance had been synthesized via microfluidic technology. Polyethylene glycol was used as a significant component added in aqueous solution of chitosan to produce such microspheres through droplets forming, chemical crosslinking and pores creating. For the improvement of adsorption capacity, thiourea was considered as an excellent choice in increasing amino functional group by graft modification. The SEM, FTIR and EDS were employed to detect distinct features of TMCM. Copper（Ⅱ） was used to test the adsorption performance of TMCM. The experimental results indicated that TMCM exhibited higher adsorption capacity（q_e= 60.6 mg g_（-1）） and faster adsorption rate than that non-modified chitosan microsphere（NMCM）.The adsorption kinetic was described well by the pseudo-second order kinetic model, which suggested that chemical adsorption along with electrons transferring was dominant in adsorption process.